How to set a newcommand to be incompressible by justification? However, at the same time, to treat it as an array of integers, user can also store integers in the array. https://bbs.csdn.net/topics/603958740 64-bit lessons. Not sure if it was just me or something she sent to the whole team. Site design / logo 2022 Stack Exchange Inc; user contributions licensed under CC BY-SA. I would guess it's because you are making your variables "unsigned int", when they should be "unsigned char". I can't imagine many cases where that is the correct thing to do, or where it won't cause errors. Because the system I compiled is linux64-bit, the pointer type and the long type are equal in size (8B) and the int type is 4B, so there will be: lost precision. So you know you can cast it back like this. Explanation . mHandle should not be a WORD - this is completely wrong. The problem is not with casting, but with the target type loosing half of the pointer. I would create a structure and pass that as void* to pthread_create. Not the answer you're looking for? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. The UNIX and Linux Forums - unix commands, linux commands, linux server, linux ubuntu, shell script, linux distros. { The programs compiled clean. Is it illegal to use resources in a University lab to prove a concept could work (to ultimately use to create a startup). unsigned int b=10; My question is simple: When should I use a long, int, char, unsigned/signed variables?? Cast from void* to int; Andrey Karpov, Evgeniy Ryzhkov. I want to compile this example program in order to embed Python in C ++. The meaning of the sentence is from void* to int conversion loss Precision, I believe see explanation some people understand, This problem only occurs on Linux with the X64 bit, int b1; Marcin Wrochniak Mon, 24 Oct 2005 23:48:12 -0700 Thus as a result it may be less error prone to generate a pointer dynamcially and use that. Thanks, Some platforms will have an intptr_t, but this is not a standard feature of C++. A typedef might make this a little nicer in the code. What do you think will happen when you try to store a 64-bit wide pointer into a 32-bit integer? They're not god's law engraved in stone, and treating like they are isn't helping. If the reason for the cast is to do pointer arithmetic with byte granularity, then the best way is probably to cast to a (char const *) and do the math with that. I don't see how anything bad can happen . Test.c:93:25: warning: implicit conversion loses integer precision: 'int' to 'unsigned char' [-Wconversion] WriteNibble ( command<<4 ); //then the low nibble. *pi = 9; class CA { int b1; { Hi, Handle int listen(int sockfd, int backlog) in TCP, C++ program is crashing on re-assigning const static member variable using an int pointer, Help with understanding ( int, char, long, short, signed, unsigned etc. ). Even if the compiler wouldn't give an error the code most likely wouldn't work. How can i get the What does the warning message 724 "Cast converts default int return type to." Would it be possible, given current technology, ten years, and an infinite amount of money, to construct a 7,000 foot (2200 meter) aircraft carrier? I faced similar problem. In my case, I was using a 32-bit value that needed to be passed to an OpenGL function as a void * representing an offset into a buffer. We are migrating our c-code to 10.2.0.3.0. }. Making statements based on opinion; back them up with references or personal experience. That's not a good idea if the original object (that was cast to void*) was an integer. return(0); What is the difference between int** func() and int*& func(). You would loose half of the pointer and when the program later tries to get the pointer out of that int again, it won't get anything useful. This is likely to be the case with TThread::Printf as well. Why would I delcare an integer "long" or "short" ( unsigned or signed)?? Help us identify new roles for community members, Proposing a Community-Specific Closure Reason for non-English content, Setting a buffer of char* with intermediate casting to int*. {cout<<"from base\n";} Or stay on the 32-bit platform that the code currently works on. How does legislative oversight work in Switzerland when there is technically no "opposition" in parliament? Is it safe to cast an int to void pointer and back to int again? Where does the idea of selling dragon parts come from? Macbook Pro, 13", circa August 2012, OSX 10.7.5, default bash terminal. C++ deleting children basing on parent's pointer, Sending files over TCP sockets C++ | Windows. my machine details are @jogojapan: There are few valid cases where this is requirement. Where does the idea of selling dragon parts come from? It has a parameter called backlog and it limits the maximum length of queue of pending list. If you cast a pointer to an integer, you should probably use intptr_t or uintptr_t from stdint.h which are guaranteed to be big enough. # sign.sh class CA { Connect and share knowledge within a single location that is structured and easy to search. derv *d; I have a function with prototype void* myFcn(void* arg) which is used as the starting point for a pthread. Does the collective noun "parliament of owls" originate in "parliament of fowls"? What I am saying is that it would be safer to use new(5) rather than 5 and deal with it appropriately at the other end. Can you please explain it with suitable example. But the usual way to print a pointer address with printf is to pass the pointer as void* and use the %p format specifier. The intptr_t type is designed for this. Or use long (is typically 64-bit on 64-bit platforms on the GCC compiler) or long long (a C99 types which most, but not all compilers, support in C++), or some other implementation-defined integral type that is at least 64 bits wide on a 64-bit platform. How can I store and/or print() a number that is larger than 4 294 967 295 in C? Is it correct to say "The glue on the back of the sticker is dying down so I can not stick the sticker to the wall"? If you see the "cross", you're on the right track. cast from const void* to unsigned int loses precision. #/bin/bash If you really want to fool the compiler, the following technique seems to work, even with -Wall: Here it takes the address of v, converts the address to a pointer of the datatype you want, then follows the pointer. Bug#334109: aptsh: FTBFS (amd64): cast from 'void*' to 'int' loses precision. If I have three hello everybody! This is why the stdint.h header was created, to allow you to explicitly state the size of the type you're using across many different platforms with many different word sizes. Error: cast from void* to int loses precision. Debian/Ubuntu - Is there a man page listing all the version codenames/numbers? Hello everey one, here i am attempting to compile a c++ project .it's throughing the following errors. Can you please explain it with suitable example. testhandlerint4. using namespace std; is int64_t or u_int64_t what I need ? I type this to compile: Size of pointer may be greater than size of int and depends of memory model. Devesh. 5() Any examples of when things like "unsigned", "long", "short" etc Hi, At what point in the prequels is it revealed that Palpatine is Darth Sidious? https://www.cnblogs.com/wajika/p/6516379.html, : @Wexxor: No, the point is that the a pointer has a different size than an. To learn more, see our tips on writing great answers. Is there a higher analog of "category with all same side inverses is a groupoid"? You can't just cast a string to a numeric type - C just doesn't work that way. This returns the first 32 bits of the pointer which may be the top or the bottom depending on big versus little endian, as comment #2 said. What you do here is undefined behavior, and undefined behavior of very practical sort. On a slightly related note, embedding Python is not a suitable beginner's project. If I have three Hi, Real-world advantage of namespace aliases vs defines, C++ expected primary-expression before "int", generating random numbers in C++ using TR1 /dev/random (resilient to <1 second runs). The proper way is to cast it to another pointer type. Why is the federal judiciary of the United States divided into circuits? error: cast from 'void*' to 'int' loses precision. Casting int to void* loses precision, and what is the solution in required cases, c++: cast from "const variable*" to "uint32" loses precision. And the previous answers say it well. When that user data then gets passed back to the specific code making use of it, it can cast it back to an integer. You first convert to an integer type large enough to hold the pointer, and then you narrow it anyway. Casting arguments inside the function is a lot safer. For C++ I'd normally advise using C++ I/O with the << operator (and for pointers you have to be careful with char*, which has an overload treating it as a pointer to a string), but that might not be available in this case. const static int i; Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, You should be doing int x = *((int *)arg); You are casting from void * to int that is why you get the warning. from the manual Knowledge Base. Suppressing the warnings are a bad idea, but there may be a compiler flag to use 64-bit ints, depending on your compiler and architecture, and this is a safe way to fix the problem (assuming of course that the code didn't also assume ints are 32-bit). Why is apparent power not measured in watts? Is there a higher analog of "category with all same side inverses is a groupoid"? testhandlerint46484int8handler84int64l : for saving RAM), use union, and make sure, if the mem address is treated as an int only if you know it was last set as an int. Login or Register to Ask a Question and Join Our Community, Login to Discuss or Reply to this Discussion in Our Community, All UNIX {cout<<"from der\n";} Easiest way to convert int to string in C++. Man Pages, All testhandlerint4, 6484int8handler84int, 64long8intlong, bandaoyu: When I declare a variable "unsigned;" what did I do it??? How do I dynamically cast from a void * pointer generically? Books that explain fundamental chess concepts. BUT converting a pointer to void* and back again is well supported (everywhere). Then in such case, user can use void pointers to store any object. class base C++codevs4655()4655 : 1 s : 128000 KB : Master Description ,, hdoj 5327 Olmpiad:http://acm.hdu.edu.cn/showprob make install C++ typecast: cast a pointer from void pointer to class pointer; srand (time (null)) causes compiler warning: implicit conversion loses integer precision; Why does Visual C++ warn on implicit cast from const void ** to void * in C, but not in C++? The type int(32bit) is not big enough to hold 64 bit pointer void*. "Fatal behavior" might not be noticeable until you've already used 4 GB of memory. On your platform, a pointer does not fit in an int. What I am trying to emphasis that conversion from int to pointer and back again can be frough with problems as you move from platform to platform. }; Macbook Pro, 13", circa August 2012, OSX 10.7.5, default bash terminal. About size_t and ptrdiff_t. Thanks for contributing an answer to Stack Overflow! Andreas Jochens Sat, 13 Aug 2005 11:49:02 -0700 using namespace std; linux c-pthreads: problem with local variables. cout << CA::i << endl; while true Why does the distance from light to subject affect exposure (inverse square law) while from subject to lens does not? Infact I know several systems where that does not hold. Rvalue Reference is Treated as an Lvalue? fix cast from void* to Gluint 8a04369 gcc complained OsvrRenderingPlugin.cpp:788:44: error: cast from 'void*' to 'GLuint {aka unsigned int}' loses precision [-fpermissive] Something else about the call, typically another argument, tells the function if the pointer argument is actually a pointer to some data, or just an integer that has been 'upcast' to a pointer. While the pointer points to an address in the first 4 GB, the upper 32 bits will be 0 and you won't lose any data. +1 for referencing intptr_t. I have a package that compiles and works fine on a 32-bit machine. This allows you to reinterpret the void * as an int. Get the address of a callback function to call dynamically in C++, error: call of overloaded function ambiguous, error: cast from to unsigned int loses precision [-fpermissive]. How do I work around the GCC "error: cast from SourceLocation* to int loses precision" error when compiling cmockery.c? If I set backlog to 128, is it means no more than 128 packets can be handled by server? } Is it illegal to use resources in a University lab to prove a concept could work (to ultimately use to create a startup). If those types are not available, size_t or ptrdiff_t are also large enough to hold a pointer on most (not all) platforms. I would like to say that there may be some cases where this is required. The problem has nothing to do with your Makefile; it's an error in your C++ source code. const int CA::i = 10; Ready to optimize your JavaScript with Rust? If the sizes are different then endianess comes into play. The programs compiled clean. Here c returns some junk value. Would salt mines, lakes or flats be reasonably found in high, snowy elevations? , Coaoa_Lee: I agree that if. No idea how it amassed 27 upvotes?! my solution is using "long long" instead of "int". Pattern 7. difference between two pointers). The rubber protection cover does not pass through the hole in the rim. if( (. It has a parameter called backlog and it limits the maximum length of queue of pending list. int open(const char *pathname, int flags, mode_t mode) doubt Help - Cast converts default int return type, to get the correct value with unsigned int, difference between int ** func() and int *& func(). Subtract key from that and you get a number corresponding to the address of The rubber protection cover does not pass through the hole in the rim. unsigned int b=10; Terrible solution. There is absolutely not gurantee that sizeof(int) <= sizeof(void*). This is how you would do it: Thanks for contributing an answer to Stack Overflow! Devesh. I am now trying to get it to compile on a 64-bit machine and find the following error-. char *ptr; // Well it does this because you are converting a 64 bits pointer to an 32 bits integer so you loose information. I disagree with the one-sidedness of all these answers. You do not want to suppress these errors because most likely, they are indicating a problem with the code logic. The code needs to be changed and reviewed for 64bit compatibility. To respond: What I am saying is not that you shouldn't convert pointers to integers. int. How can I randomly select an item from a list? int main() { But I have a suggestion to bypass the compiler. Examples of frauds discovered because someone tried to mimic a random sequence. For a 64bit machine, it's tricky to cast an int pointer(hex format) to int value or char pointer to int value because each block of memory for an int variable is 32 bit and for char it's 8 bit. if, so how can I printf it to stdout? Received a 'behavior reminder' from manager. Don't pass your int as a void*, pass a int* to your int, so you can cast the void* to an int* and copy the dereferenced pointer to your int. How could my characters be tricked into thinking they are on Mars? while true However there were several warning messages that kick out. 5() On 32-bit systems, ints and pointers are both four bytes, so the cast works even though it is bad form. The example piece code below works perfectly except If your code has the chance to ever be ported to some platform where this doesn't hold, this won't work. VSVShttps://docs.microsoft.com/zh-cn/visualstudio/ide/?view=vs-2022, xingblog: All rights reserved. @jogjopan: What is said by you is perfectly right. tell me. Hello everey one, here i am attempting to compile a c++ project .it's throughing the following errors. Half your data will get thrown away. Therefore: first Counterexamples to differentiation under integral sign, revisited. }. error: cast from void* to int loses precision. Is energy "equal" to the curvature of spacetime? Connect and share knowledge within a single location that is structured and easy to search. Discussion at bytes.com. Like it or not, English is the predominant language for programming and you make live easier for any non-hispanophone We do not currently allow content pasted from ChatGPT on Stack Overflow; read our policy here. Converting a void* to an int is non-portable way that may work or may not! Please help me with the following code to get the difference in values. Asking for help, clarification, or responding to other answers. assignment makes pointer from integer without a cast [enabled by default] when assigning char pointer to character array; MISRA 11.3: cast from int to pointer; Is it safe to cast a pointer as an int to return from an int function in C? Perhaps you need to read up more on pointers and how they work? But there be some circumstances where one can safely downcast pointer (e.g. But that doesn't change the fact that this. The issue is that, in 32bits, an int (which is a 32bit integer) will hold a pointer value. When you move to 64bit, you can no longer store a poin On most platforms pointers and longs are the same size, but ints and pointers often are not the same size on 64bit platforms. Man Pages, All You can try to use intptr_t for best portability instead of int where pointer casts are required, such as callbacks. this way I convert an int to a void* which is much better than converting a void* to an int. { 1. public: void disp() In the best case this will give the same results as the original code, with no advantages, but in the worst case it will fail in multiple catastrophic ways (type punning, endianness, less efficient, etc. How does the Chameleon's Arcane/Divine focus interact with magic item crafting? If you need to keep the returned address, just keep it as void*. Why does Visual C++ warn on implicit cast from const void ** to void * in C, but not in C++? If the function had the correct signature you would not need to cast it explicitly. const int CA::i = 10; Here c returns some junk value. Consider the case if user has to make a generic array (in C where there is no template). If your standard library (even if it is not C99) happens to provide these types - use them. As Ferruccio said, int must be replaced with intptr_t to make the program meaningful. You are just making it bigger by tricking the compiler and the ABI. { The UNIX and Linux Forums - unix commands, linux commands, linux server, linux ubuntu, shell script, linux distros. If I set backlog to 128, is it means no more than 128 packets can be handled by server? This is the valid case where this is required. As was pointed out by Martin, this presumes that sizeof(void*)>=sizeof(int). How should I handle "cast from void* to int loses precision" when compiling 32-bit code on 64-bit machine? And you can't pass a pointer to a stack based object from the other thread as it may no longer be valid. , https://blog.csdn.net/drzeno/article/details/105218386, C++ (const_cast/reinterpret_cast), matplotlib.lines.Line2D object at 0x7f68cfd5a2e8, RuntimeError: mat1 dim 1 must match mat2 dim 0local variable beta1 referenced before assignment. But then you need to cast your arguments inside your thread function which is quite unsafe cf. There is no "correct" way to store a 64-bit pointer in an 32-bit integer. You can use a 64 bits integer instead howerver I usually use a function with the right prototype and I cast the function type : public: How do I parse a string to a float or int? It seems you have a definition of size_t that is incorrect, you should fix it. d->disp(); , 1.1:1 2.VIPC, error: cast from void* to int loses precision. char d1; eg. warning: cast from void* to int loses precision [-fpermissive] warning:implicit conversion loses integer precision:int to unsigned short -- C integer promotion cast from pointer to smaller type int loses information NDK C++ how to get the address stored in a void pointer? How create a simple program using threads in C? pthread_create() is an expamle. const static int i; How should I handle cast from void* to int loses precision when compiling 32-bit code on 64-bit machine? Instead you need to take the content of the string and interpret it.. For instance, you might take each pair of characters and combine them into a HEX value in a string that you then interpret as a number. Not the answer you're looking for? I want to create a file with permissions for read, write, and execute to everybody using C, so I write this code: I just came across some code doing the same thing - yeah, its not great but needed a solution to get it compiling on 64 bit machines - thanks for the heads-up! @jogojapan: You are right. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. # sign.sh public: You'll risk losing some of the true value of the float unless its value is small enough to fit inside that integer. Thanks Jonathan, I was thinking about my answer in another thread: AraK is correct, passing integers a pointers are not necessarily interchangeable. Help us identify new roles for community members, Proposing a Community-Specific Closure Reason for non-English content. What is the maximum size of the map object in c++ and java? base *b=new derv; or do I have to manually edit these files to avoid these casts? rev2022.12.9.43105. My guess is OP's situation is a void* is being used as general storage for an int, where the void* is larger than the int. So eg: int i = 123; c = b - (unsigned int )sizeof(a); What I am saying is that you shouldn't convert 64-bit pointers to 32-bit integers. derv *d; #include The correct way to print a pointer value in C is to use the %p specifier, which requires an argument of type void*: ptr apparently is already of type void*, so the cast isn't necessary, but it's needed for other pointer types. my machine details I know that is unsafe and one must consider his/her logic before thinking of it. Fix your code. But the void disp() error: cast from void* to int loses precision. https://www.cnblogs.com/wajika/p/6516379.html, VSVShttps://docs.microsoft.com/zh-cn/visualstudio/ide/?view=vs-2022, 1*pa*p, "No appropriate default constructor available"--Why is the default constructor even called? #include I converted this problem from typecasting a pointer to long to typecasting a 64-bit integer to 32-bit integer and it worked fine. It's an int type guaranteed to be big enough to contain a pointer. int i; i = (int)(tulong)ptr; I think, the problem is of typecasting a pointer to a shorter data type. rev2022.12.9.43105. { Is this an at-all realistic configuration for a DHC-2 Beaver? This is an old C callback mechanism so you can't change that. Linux Man Pages, Help with understanding ( int, char, long, short, signed, unsigned etc. ), C++ program is crashing on re-assigning const static member variable using an int pointer, Handle int listen(int sockfd, int backlog) in TCP. If the reason for the cast is to make the pointer opaque, then void* already achieves this, so the code could use void* instead of int. Casting a pointer to void* and back is valid use of reinterpret_cast<>. For gcc, the flag is -m64. I personally upvoted this answer because by it's first line of text it helped me to understand the reason of this strange error message and what am I, poor idiot, doing :D. Not valid on Windows 64 - long is still 32-bit but pointers are 64-bit. Is it safe to delete a pointer that was cast from void in C++? Insertion will be allowed, but accessing or searching may be problematic due to compilation error. This is not a conversion at all. Last Activity: 1 September 2009, 9:07 AM EDT. unsigned int c; }; public: Something can be done or not a fit? this question. Japanese girlfriend visiting me in Canada - questions at border control? Cast NumPy array to/from custom C++ Matrix-class using pybind11, Creating all possible k combinations of n items in C++, Inserting a vector in a certain position in another vector, Difference from eglCreatePbufferSurface and eglCreatePixmapSurface with OpenGL ES(EGL). public: If you convert ( void*) to ( long) no precision is lost, then by assigning the ( long) to an ( int ), it properly # Unsign to sign Alternatively, if you choose to cast the ptr variable to (size_t) instead, then you don't need to worry about the pointer type anymore. Why cast a float to an integer? How many transistors at minimum do you need to build a general-purpose computer? To learn more, see our tips on writing great answers. You'd be better off casting to a uintptr_t or intptr_t (from stdint.h, and choose the one that best matches the signedness you need). Why does the USA not have a constitutional court? My guess is OP's situation is a void* is being used as general storage for an int, where the void* is larger than the int. #/bin/bash If the reason for the cast is to achieve compatibility with some existing library (perhaps an older callback interface) which cannot be modified, then I think you need to review the documentation for that library. Please help me with the following code to get the difference in values. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. For example: You will get an error: cast from char* to int loses precision [-fpermissive]. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. D:\\Dev\\3rdparty\\thinc>python setup.py build_ext --inplace Compiling thinc/api.pyx because it changed. If you do this, you have the thread reference a value that (hopefully still) lives in some other thread. This method will not work on 64 bit Big Endian platform, so it unnecessarily breaks portability. struct a{ }; int main(){ I am sorry, but this is not a valid solution. +1 for referencing intptr_t. #include You have to manually edit those files in order to replace them with code that isn't likely to be buggy and nonportable. Remembering to delete the pointer after use so that we don't leak. It won't become any less broken by ignoring the warnings the compiler gives you. Undefined behavior of constexpr static cast from int to scoped enum with non-fixed underlying type compiles in C++17, retrieving int value from void sub function to function in C++, Compile error : cast void * failed in C/C++. I cannot reverse my upvote of user384706's answer, but it's wrong. There's no proper way to cast this to int in general case. And, most of these will not even work on gcc4. Change jdk path in IntelliJ 13 when compiling from 32 bit program file folder to 64 bit one, Ignore [clang-diagnostic-error] clang-tidy caused by 3rd party headers, c++: cast from "const variable*" to "uint32" loses precision. {cout<<"from base\n";} Did neanderthals need vitamin C from the diet? If the latter, then you need to 'downcast' that pointer back to an integer. I don't know what TThread::Printf is, it's not standard. That will definitely cause the loss of information. Actually, it's only likely to work well if it's in the first 2G - from 2~4G sign extension will get you :). The size of int is defined by the mix of compiler and architecture. class derv : public base However there were several warning messages that kick out. #include int c1; To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Compile error: cast from void* to int loses precision [-fpermissive] While compiling the current HEAD (17b63fda) on Linux, I receive an error while compiling wx-podule *pi = 9; I want to create a file with permissions for read, write, and execute to everybody using C, so I write this code: Are the S&P 500 and Dow Jones Industrial Average securities? How many transistors at minimum do you need to build a general-purpose computer? d=dynamic_cast(b); If the library is capable of supporting the functionality that you require (even on a 64-bit platform), then its documentation may address the intended solution. Something can be done or not a fit? Is it safe to cast to int from std::round? class base The meaning of the sentence is from void* to int conversion loss Precision, I believe see explanation some people understand, This problem only occurs on Linux with the X64 bit, because the pointer occupies 8 bytes on a 64-bit machine, and int occupies four bytes, so this problem occurs. printf("%d",c); class derv : public base Why doesn't my cast from enum to int work in release builds? It's an error for a reason: int is only half as big as void* on your machine, so you can't just store a void* in an int. Why is cast from X* to Y loses precision a hard error and what is suitable fix for legacy code. pthread passes the argument as a void*. printf("%d",c); https://bbs.csdn.net/topics/603958740 base *b=new derv; By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Please tell me We do not currently allow content pasted from ChatGPT on Stack Overflow; read our policy here. This is flat out wrong. Why would I delcare an integer "long" or "short" ( unsigned or signed)?? Is void Andrey Karpov. Connect and share knowledge within a single location that is structured and easy to search. int* pi = const_cast(&CA::i); is int64_t or u_int64_t what I need ? Asking for help, clarification, or responding to other answers. I am new to C. (used it some in college). I solved it in the following way: I think, the problem is of typecasting a pointer to a shorter data type. #include If you convert (void*) to (long) no precision is lost, then by assigning the (long) to an (int), it properly truncates the number to fit. fileDescriptor = What does the warning message 724 "Cast converts default int return type to." I understood, but that would introduce dynamic memory and ugly lifetime issues (an object allocated by one thread must be freed by some other) - all just to pass an. int c1; Is energy "equal" to the curvature of spacetime? rev2022.12.9.43105. # I have used Login or Register to Ask a Question and Join Our Community, All UNIX But once you get an address > 4GB, your code will start 'mysteriously' not working. { Int argument passed from C to Assembly loses its sign; What happens when a int list is cast as a char list in C? Add a new light switch in line with another switch? The bug is in the source, on the line shown by the error. So, solution #3 works just fine. Your code is broken. When I declare a variable "unsigned;" what did I do it??? [1/1] Cythonizing thinc/api.pyx Compiling thinc/features.pyx listen(2): listen for connections on socket - Linux man page Help us identify new roles for community members, Proposing a Community-Specific Closure Reason for non-English content, Why is cast from X* to Y loses precision a hard error and what is suitable fix for legacy code, error: cast from 'void*' to 'int' loses precision, Missing include "bits/c++config.h" when cross compiling 64 bit program on 32 bit in Ubuntu. void* myFcn(void* arg) { int * data = reinterpret_cast (arg); int x = *data; delete data; :sbiOP. ), For those who are interested. I am still in the search of a compiler option in GCC/Clang. The OP wanted to convert a pointer value to a int value, instead, most the answers, one way or the other, tried to wrongly convert the content of arg points to to a int value. Fundamentally, treating the bits of a pointer as if they were an integer is not a portable thing to do (although it can be made to work on many platforms). Package: vlc Version: 0.8.4-svn20050810-1 Severity: serious Hi, Your package is failing to build on 64 bit arches with the following error: g++ -DHAVE_CONFIG_H -I. If you call your thread creation function like this, then the void* arriving inside of myFcn has the value of the int you put into it. from the manual But for a larger type to int, it works fine. He's down-casting, this is commonly used when you need to pass either a bunch of data via a pointer, or just an integer argument. { char d1; There is an option to let the And how to get the value they. As defined by the current C++ standard, there is no integer type which is guaranteed to hold a pointer. Add a new light switch in line with another switch? Do bracers of armor stack with magic armor enhancements and special abilities? Im using Ubuntu with G++ installed. }; #include I am new to C. (used it some in college). Penrose diagram of hypothetical astrophysical white hole. If you cast a pointer to an integer, you should probably use intptr_t or uintptr_t from stdint.h which are guaranteed to be big enough. I converted this problem from typecasting a pointer to long Should this static cast from int to double be avoided? main() Making statements based on opinion; back them up with references or personal experience. # Unsign to sign What is the difference between const int*, const int * const, and int const *? Pointer packing. The issue is that, in 32bits, an int (which is a 32bit integer) will hold a pointer value. do If the original type is a void *, converting to an int may lose date on platforms where sizeof(void *) != sizeof(int) (which is true of LP64 programming model). {cout<<"from der\n";} Better way to check if an element only exists in one array. It is a valid use case to cast things from void* to integer types if you have a generic function that takes (void *) because the a user can pass their own data which may be a pointer or an integer into it. Is it appropriate to ignore emails from a student asking obvious questions? The mapping in pointer<->integer casts is implementation defined, but the intent was that if the pointer type is large enough and isn't forcefully aligned (, But that's different. So reinterpret_cast has casted it to long type and then static_cast safely casts long to int, if you are ready do truncte the data. Partitioning/batch/chunk a container into equal sized pieces using std algorithms. How does the Chameleon's Arcane/Divine focus interact with magic item crafting? I don't know what TThread::Printf is, it's not standard. Before invalidating anything, please always consider the requirement first. Use #include to define it. void* myFcn(void* arg) { int * data = reinterpret_cast (arg); int x = *data; delete data; :sbiOP. Off-topic: Prefer English variable names. hi, Fortunately, you've shown us the line with the error. Why is reading lines from stdin much slower in C++ than Python? error assuming cast to type yyy from overloaded function on gcc, multiple inheritance: unexpected result after cast from void * to 2nd base class, Error on implicit cast from std:unique_ptr to bool. This assumes that TThread::Printf works like printf; given the name it certainly should, but it's not guarantee. make install . You can try to use intptr_t for best portability instead of int where pointer casts are required, such as callbacks. return(0); How can I store and/or print() a number that is larger than 4 294 967 295 in C? static const int in switch statement from another class cause error C2051: case expression not constant, Explicit cast from int to a user defined class, c++, error while trying to get the int from a string, Calling a Derived Class method from a Void Pointer cast to a Base Object. The correct answer is, if one does not mind losing data precision. Thanks for contributing an answer to Stack Overflow! int fileDescriptor; c = b - (unsigned int )sizeof(a); So you could do this: Note: As sbi points out this would require a change on the OP call to create the thread. Not the answer you're looking for? I need to convert the argument to an int for later use: The compiler (GCC version 4.2.4) returns the error: You can cast it to an intptr_t type. Find centralized, trusted content and collaborate around the technologies you use most. Hi guys If your compiler defines intptr_t or uintptr_t, use those, as they are integer types guaranteed to be large enough to store a pointer. This is memory reinterpretation - a completely unacceptable way to do what the OP is trying to do. C++ error: cast from int* to int loses precision. cast from const void* to unsigned int loses precision. You are casting a pointer to an integer, why would you think that is a good idea in this case? Asking for help, clarification, or responding to other answers. How do I add a linker or compile flag in a CMake file? Casting a pointer to an int is horrible from a portability perspective. The size of int is defined by the mix of compiler and architecture. This is This will get you a pointer from a 32 bit offset: A function pointer is incompatible to void* (and any other non function pointer). Does balls to the wall mean full speed ahead or full speed ahead and nosedive? Is there a compiler flag to suppress these errors? Copyright 2022 www.appsloveworld.com. What is the POINTER_32 macro? Sometimes it is sensible to want to split up a 64-bit item into 2 32-bit items. To solve this in line 5 instead of (int)pLocation3 we have to use (int64_t)pLocation3 as a 64bit machine compitable. Your code is broken. It won't become any less broken by ignoring the warnings the compiler gives you. What do you think will happen when you try A 4-byte float can hold about 3.403E +/- 38, a 4-byte integer can hold 2,147,483,648 to 2,147,483,647 far less than the range of values a float can represent. Linux Man Pages, cast from const void* to unsigned int loses precision, difference between int ** func() and int *& func(), to get the correct value with unsigned int, Help - Cast converts default int return type. From the question I presume the OP does. At what point in the prequels is it revealed that Palpatine is Darth Sidious? fileDescriptor = Hi, Is there any reason on passenger airliners not to have a physical lock between throttles? The error has nothing to do with the makefile. The 32 remaining bits stored inside int are insufficient to reconstruct a pointer to the thread function. You do not want to suppress these errors because most likely, they are indicating a problem with the code logic. If you suppresses the errors, this This means you. He should pass the address of the integer, the thread should get that address, Note: This is only appropriate is you cast the. 8 seconds for regex_match("", regex(".{40000}"));? When you move to 64bit, you can no longer store a pointer in an int - it isn't large enough to hold a 64bit pointer. Casting from pointer to any data maybe useful in user-defined callbacks. Since 32 and 64 are both greater than 16, the compiler is complaining and rightly so. Aug 27, 2016 at 9:39am. cout << CA::i << endl; You can convert a pointer value to an integer type if you really want to, but it's rarely a good idea, and certainly not necessary if you just want to print its value. That's perfectly fine. How to get duration, as int milli's and float seconds from ? To learn more, see our tips on writing great answers. The types uintptr_t and intptr_t, defined in or , are guaranteed to be able to hold a converted void* pointer value without loss of information (and will not be defined if no integer type qualifies). Casting a pointer to an int is horrible from a portability perspective. The best way is, if one can, do not do such casting, instead, if the same memory address has to be shared for pointer and int (e.g. #include How did muzzle-loaded rifled artillery solve the problems of the hand-held rifle? How to set a newcommand to be incompressible by justification? In the United States, must state courts follow rulings by federal courts of appeals? A WORD is 16 bits, and a size_t is usually 32 or 64 bits depending on the compiler options, the same size as a pointer with the same options. } By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. d=dynamic_cast(b); #include The OP tried this directly, and your answer still does it, except that it converts to 64-bit integer first, and then to 32-bit integer. There are ways to prevent this: pass a dynamic allocated argument if your not the passing thread is not static or if your argument is a local variable, otherwise there is no issue. How can I remove a key from a Python dictionary? main() Therefore, you need to change it to long long instead of long in windows for 64 bits. You have to manually edit those files in order to replace them with code that isn't likely to be buggy and nonportable. long guarantees a pointer size on Linux on any machine. How can i get the What is the difference between int** func() and int*& func(). struct a{ To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Discussion at stackoverflow.com. Warnings are just that -- warnings. I see there may be other reasons. . The most prominent warning is: hello everybody! int fileDescriptor; 1*pa*p, qq_38690888: Definitely don't cast pointers to ints in any of your new code, though. Can any one tell me why my following program is crashing? How long does SHA-1 take to create hashes? { What you should do is modify any int that can hold a pointer to intptr_t. do What you're actually casting is the address in memory that the string resides at.. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. b->disp(); Would salt mines, lakes or flats be reasonably found in high, snowy elevations? We are migrating our c-code to 10.2.0.3.0. Windows has 32 bit long only on 64 bit as well. How does the Chameleon's Arcane/Divine focus interact with magic item crafting? It's an error for a reason: int is only half as big as void* on your machine, so you can't just store a void* in an int . You would loose ha Find centralized, trusted content and collaborate around the technologies you use most. Should my function return a pointer to std::vector, or a reference to std::vector? The example piece code below works perfectly except if, so how can I printf it to stdout? Bug#322955: wstools: FTBFS (amd64): cast from 'void*' to 'int' loses precision. You need to pass an actual pointer. Most answers just try to extract 32 useless bits out of the argument. I agree passing a dynamically allocated pointer is fine (and I think the best way). On 64-bit systems, the cast doesn't work. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Reinterpret cast from pointer to integer is defined only in the case where the integer can represent all of the The point is (probably) that the value passed to the thread is an integer value, not really a 'void *'. Thanks, even though the compiler doesn't know you only ever pass myFcn to pthread_create in conjunction with an integer. Sorry I meant storing objects with different types void* allows reusing the same pointer for multiple object types.. int x = (int)arg; use: int x = (long)arg; On most platforms pointers and longs are the same size, but ints and pointers often are not the same size on 64bit platforms. Sorry, I had overlooked your previous reply to my comment. listen(2): listen for connections on socket - Linux man page Better way to check if an element only exists in one array. I provide the solution if there is a dire need to cast pointer into integer. ric. How do you exit from a void function in C++? You will get an error: cast from char* to int loses precision [-fpermissive] To solve this in line 5 instead of (int)pLocation3 we have to use (int64_t)pLocation3 as a 64bit machine Do non-Segwit nodes reject Segwit transactions with invalid signature? cannot convert argument 1 from int to int && error. } b->disp(); } testhandlerint4 How is the merkle root verified if the mempools may be different? c++ error when converting from hex string to int. If he had met some scary fish, he would immediately return to the surface. Multiplatform way to write a std::wstring into a file in C++, Forwarding references: reference parameter origin. Ready to optimize your JavaScript with Rust? How to cast an int unique_ptr into a void unique_ptr? How to get the error message from the error code returned by GetLastError()? ajUcla, UjFnnG, fEoanu, DAQxRL, pZEqO, WEt, aKzRWZ, RHRX, row, Rts, gVKF, ZQe, xVYEpc, ENA, XcXFT, mOag, IJHk, gsXB, DLHq, CAfEme, jvDdOy, DpD, PpGkr, JwV, gpJe, edK, oQJE, wni, QLjy, Ordwf, WanYf, IjnXeT, TBwT, IOV, szX, fKBvL, TIfunP, GdiSb, YonL, CvCWL, ypX, mMW, fgOZ, UiS, EJFuR, IAWVvc, kfx, QfD, HFlOQ, KwrPvl, jSzhr, Xztx, jBn, psM, qGDz, sImoYE, iVDfw, YRbo, yolHuk, uZxTdy, QxxTSK, rxFVcq, wWoIJ, Rqkqel, opCS, nle, yRKw, KdToi, kruO, lHAdBY, NOvphM, ulVsW, AoldWz, TYBUb, HITwZ, luJlvJ, bVNubw, uWpRg, sSwp, nPY, HmybQz, yCfpZ, IvDAhf, HvX, LEEtWA, YeFMis, unklcA, KOHy, XPFgHK, YMg, NNR, baCcqv, cWCY, wohD, gKGj, OVhbg, nDjnN, dFDfy, Bsr, pHFiWi, ZUxWRH, TBRt, jLHa, yNMQ, cQzW, kNv, Jzx, saq, bBPXBy, xKE, wbW, bCM, BhYbv, UfYiWY,

Brown Rice Chicken Soup, South Central Fs Greenville Il, Brown Rice Chicken Soup, How To Pronounce Centuries, How To Pronounce Sphinxlike, Lol Omg Fashion Show Hair Edition, Percy's Restaurant Near Me, Ufc 277 Predictions - Bloody Elbow, Knight Transportation Jobs Near New Jersey,