cast to void *' from smaller integer type 'int

It's always a good practice to put your #define's in brackets to avoid such surprise. pthread create managing values generated in function (in c), Establishing TCP socket connection between PHP client and C server on Ubuntu. What is the purpose of non-series Shimano components? The text was updated successfully, but these errors were encountered: But I don't want to edit code in "EAGLView.mm" because it's a "library file". Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? Please unaccept the answer you have chosen as it is wrong (as the comments below it say) and will lead to bugs. 1. For example, the main thread could wait for all of the other threads to end before terminating. Mutually exclusive execution using std::atomic? Why does setupterm terminate the program? Just re-enforcing the old behavior of Xcode 5.0 and earlier versions, that already cut away parts of the address by casting it to int, won't introduce any new bugs and avoids the need to learn and understand lots of implementation-internal cocos code. This is why you got Error 1 C2036, from your post. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? Remembering to delete the pointer after use so that we don't leak. Using an integer address (like &x) is probably wrong, indeed each modification you will execute on x will affect the pass behaviour. It is done by the compiler on its own, without any external trigger from the user. : iPhone Retina 4-inch 64-bit) is selected. 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. All character types are to be converted to an integer. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? Converting a void* to an int is non-portable way that may work or may not! Maybe you can try this too. vegan) just to try it, does this inconvenience the caterers and staff? converted back to pointer to void, and the result will compare equal What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? It is purely a compile-time directive which instructs the compiler to treat expression as if it had . If your standard library (even if it is not C99) happens to provide these types - use them. byte -> short -> char -> int -> long -> float -> double. However the actual code in question contains an explicit c-style cast to int. Find centralized, trusted content and collaborate around the technologies you use most. C99 standard library provides intptr_t and uintptr_t typedefs, which are supposed to be used whenever the need to perform such a cast comes about. Here, the Java first converts the int type data into the double type. Thus as a result it may be less error prone to generate a pointer dynamcially and use that. To be honest, I think, clang is too restrictive here. I recall there was a TreeNode(int) early on prior to 1.0 release I can't remember why I removed it, if I should felt it was easy enough to cast to (void*) or if it was because it created type inference conflict at the call site. So the compiler is very picky here and the correct solution to make the code compile again and still let it show the exact same behavior like in Xcode 5.0 is to first cast to an integer type with a size that matches the one of a pointer and to then do a second cast to the int that we actually want: ids [i] = (int) (size_t)touch; A cast is a way of explicitly informing the compiler that you intend to make the conversion and that you are aware that data loss might occur, or the cast may fail at run time. I would create a structure and pass that as void* to pthread_create. Whats the grammar of "For those whose stories they are"? Using indicator constraint with two variables. The nature of simulating nature: A Q&A with IBM Quantum researcher Dr. Jamie We've added a "Necessary cookies only" option to the cookie consent popup. This page was last modified on 12 February 2023, at 18:25. Whats the grammar of "For those whose stories they are"? How to get the error message from the error code returned by GetLastError()? How to use Slater Type Orbitals as a basis functions in matrix method correctly? Noncompliant Code Example (memset())For historical reasons, certain C Standard functions accept an argument of type int and convert it to either unsigned char or plain char. For example, if you want to store a 'long' value into a simple integer then you can type cast 'long' to 'int'. Since the 'size' argument for your function is the number of bytes each element in the array needs, I think casting the pointerto (char*) is appropriate. Thanks. 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. Note:You might receive a runtime exception if the pointer contains a value unsuitable for the context. XCode 5.1 is change all architecture to 64 bit. I have a function with prototype void* myFcn(void* arg) which is used as the starting point for a pthread. SCAN_PUT_ATTR(mask, ATTR, smask, FUNC); You should perform type conversion based on 64bit build system because the type "int" supports only -32768 ~ 32768. I am compiling this program in linux gcc compiler.. ^~~~~~~~~~~~~~~~~~~~~ A cast converts an object or value from one type to another. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. As a result of the integer division 3/2 we get the value 1, which is of the int type. I'm only guessing here, but I think what you are supposed to do is actually pass the address of the variable to the function. The nature of simulating nature: A Q&A with IBM Quantum researcher Dr. Jamie We've added a "Necessary cookies only" option to the cookie consent popup. Why do academics stay as adjuncts for years rather than move around? Floating-point conversions The difference between the phonemes /p/ and /b/ in Japanese, Styling contours by colour and by line thickness in QGIS. Thanks Jonathan, I was thinking about my answer in another thread: AraK is correct, passing integers a pointers are not necessarily interchangeable. That's not a good idea if the original object (that was cast to void*) was an integer. The 32 remaining bits stored inside int are insufficient to reconstruct a pointer to the thread function. However, I believe that even if the define was for the "65536", it would not be what @kaetzacoatl wanted. Recovering from a blunder I made while emailing a professor. SCAN_PUT_ATTR(key, ATTR, skey, FUNC); Connect and share knowledge within a single location that is structured and easy to search. @Martin York: No, it doesn't depend on endiannness. This forum has migrated to Microsoft Q&A. The problem is not with casting, but with the target type loosing half of the pointer. Cast characters to unsigned char before converting to larger integer sizes Created by Robert Seacord, last modified by Jill Britton on Oct 03, 2022 Signed character data must be converted to unsigned char before being assigned or converted to a larger signed type. @DavidHeffernan I rephrased that sentence a little. Star 675. 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. SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); In both cases, converting the pointer to an integer type that's too small to represent all pointer values is a bug. If you really need such trickery, then consider one of dedicated types, which are intptr_t and uintptr_t. If it's anything like cocos2d-iphone v2.x and just based on this slice of code in a core class I wager it's safe to say that cocos2d-x 2.x also is not compatible with 64 bit code, and you can expect all kinds of issues (not just compile-time but also runtime). Can Martian regolith be easily melted with microwaves? return ((void **) returnPtr);} /* Matrix() */. ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] If you preorder a special airline meal (e.g. Fork 63. Pd = Pa; Similarly, Pc may be type cast to type int and assigned the value Pa. 1. How do I set, clear, and toggle a single bit? On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. Sign up for a free GitHub account to open an issue and contact its maintainers and the community. Projects. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. The high-order 9 bits of the number are used to hold a flag value, and the result is converted back into a pointer. The main point is: a pointer has a platform dependent size. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. SCAN_PUT(ATTR, NULL); Bulk update symbol size units from mm to map units in rule-based symbology. warning C4311: 'type cast': pointer truncation from 'void *' to 'long' in ECPG test files. Thanks for contributing an answer to Stack Overflow! How to notate a grace note at the start of a bar with lilypond? Surely the solution is to change the type of ids from int to type that is sufficiently large to hold a pointer. This is a fine way to pass integers to new pthreads, if that is what you need. Offline ImPer Westermark over 11 years ago in reply to Andy Neil Except that you sometimes stores an integer in the pointer itself. The text was updated successfully, but these errors were encountered: You signed in with another tab or window. There's no proper way to cast this to int in general case. How to use Slater Type Orbitals as a basis functions in matrix method correctly? Basically its a better version of (void *)i. I need to cast the int from the first function so that I can use it as an argument for the second function. For the remaining integral types, the result is the value of the enum if it can be represented by the target type and unspecified otherwise. Yeah, the tutorial is doing it wrong. ../lib/odp-util.c:5603:13: note: expanded from macro 'SCAN_PUT' to the original pointer: The following type designates an unsigned integer type with the So you could do this: Note: As sbi points out this would require a change on the OP call to create the thread. Using printf with a pointer to float gives an error, Meaning of int (*) (int *) = 5 (or any integer value), Casting int to void* loses precision, and what is the solution in required cases, Acidity of alcohols and basicity of amines. lexborisov Modest Public. itch" "-I..\include\windows" "-Iinclude" "-I..\include" "-I..\datapath-windows\include" "-IC:\PTHREADS-BUILT\include" "-Xclang" "-fcolor-diagnostics" "-pipe" By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. But you seem to suggest by your answer that the user can pass 5 to pthread_create and then perform the above cast to get it back. Making statements based on opinion; back them up with references or personal experience. I think the solution 3> should be the correct one. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. I cannot reverse my upvote of user384706's answer, but it's wrong. Thank you all for your feedback. } SCAN_END_SINGLE(ATTR) A pointer converted to an integer of sufficient size and back to the same pointer type is guaranteed to have its original value, otherwise the resulting pointer cannot be dereferenced safely ( the round-trip conversion in the opposite direction is not guaranteed [.]) Half your pointer will be garbage. Why does flowing off the end of a non-void function without returning a value not produce a compiler error? Hence there is no loss in data. use $(ARCHS_STANDARD_32_BIT) at Architecture instead of $(ARCHS_STANDARD). But then you need to cast your arguments inside your thread function which is quite unsafe cf. Making statements based on opinion; back them up with references or personal experience. To perform a cast, specify the type that you are casting to in parentheses in front of the value or variable to be converted. Please note that the error I am receiving is "cast to smaller integer type 'int' from 'string' (aka 'char *')" referencing line of code: while (isalpha (residents [i].name) == 0). What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? I'm using cocos2d-x-2.2.2. ../lib/odp-util.c:5601:9: note: expanded from macro 'SCAN_PUT' If your code has the chance to ever be ported to some platform where this doesn't hold, this won't work. Yeah, the tutorial is doing it wrong. The nature of simulating nature: A Q&A with IBM Quantum researcher Dr. Jamie We've added a "Necessary cookies only" option to the cookie consent popup. Can anybody explain how to pass an integer to a function which receives (void * ) as a parameter? How can this new ban on drag possibly be considered constitutional? How do I align things in the following tabular environment? ), For those who are interested. @kshegunov said in Number Type Cast: const void * x; int y = int (x); compiles just fine. Update: Today, i download the latest version of cocos2d-x (cocos2d-x 2.2.3). to your account, [87/252] Compiling C object lib/libopenvswitch.a.p/odp-util.c.obj As was pointed out by Martin, this presumes that sizeof(void*)>=sizeof(int). On many systems, an 8-bit unsigned int can be stored at any address while an unsigned 32-bit int must be aligned on an address that is a multiple of 4. Most answers just try to extract 32 useless bits out of the argument. How do I force make/GCC to show me the commands? For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. C99 standard library provides intptr_t and uintptr_t typedefs, which are supposed to be used whenever the need to perform such a cast comes about. There's probably little you can do except look or hope for a fixed 2.x version or upgrade to 3.x (I would assume it's 64-bit safe but this is just a guess, do research this issue before you upgrade). Mutually exclusive execution using std::atomic? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. The difference between the phonemes /p/ and /b/ in Japanese, Styling contours by colour and by line thickness in QGIS, AC Op-amp integrator with DC Gain Control in LTspice, Identify those arcade games from a 1983 Brazilian music video. But, sure, in that specific case you can pass a local variable address, type casting integer to void* [duplicate]. By clicking Sign up for GitHub, you agree to our terms of service and a cast of which the programmer should be aware of what (s)he is doing. Well it does this because you are converting a 64 bits pointer to an 32 bits integer so you loose information. *sound/soc/codecs/tlv320aic32x4.c:1202:18: warning: cast to smaller integer type 'enum aic32x4_type' from 'void *' @ 2022-04-22 9:48 kernel test robot 0 siblings, 0 . You are getting warnings due to casting a void* to a type of a different size. To learn more, see our tips on writing great answers. error: cast from pointer to smaller type 'unsigned int' loses information. whether it was an actual problem is a different matter though. that any valid pointer to void can be converted to this type, then Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Only the following conversions can be done with static_cast, except when such conversions would cast away constness or volatility. Therefore, you need to change it to long long instead of long in windows for 64 bits. It solved my problem too. (void *)i Error: cast to 'void *' from smaller integer type 'int' PS: UBUNTUCLANG3.5 clang -O0 -std=gnu11 -march=native -lm -lpthread pagerank.c -o pagerank c pthreads 4 10.3k 2 21 2015-06-05 cast operators [edit] When an expression is used in the context where a value of a different type is expected, conversionmay occur: intn =1L;// expression 1L has type long, int is expectedn =2.1;// expression 2.1 has type double, int is expectedchar*p =malloc(10);// expression malloc(10) has type void*, char* is expected casting from int to void* and back to int. Connect and share knowledge within a single location that is structured and easy to search. It's an int type guaranteed to be big enough to contain a pointer. Not the answer you're looking for? You cannot just cast the 32-bit variable to a pointer, because that pointer on a 64-bit machine is twice as long. Can I tell police to wait and call a lawyer when served with a search warrant? how to cascade 2d int array to 2d void pointer array? what happens when we typecast normal variable to void* or any pointer variable? p-util.c.obj "-c" ../lib/odp-util.c . ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' This is not even remotely "the correct answer". Put your define inside a bracket: without a problem. Please tell me error: cast from 'void*' to 'int' loses precision, How Intuit democratizes AI development across teams through reusability. That's probably going to be true for most platforms you will ever encounter, but it's not a guarantee; it's implementation-dependent. How create a simple program using threads in C? Is it suspicious or odd to stand by the gate of a GA airport watching the planes? Converting one datatype into another is known as type casting or, type-conversion. this way I convert an int to a void* which is much better than converting a void* to an int. C++ how to get the address stored in a void pointer? C/C++ , Cerror: cast to 'void *' from smaller integer type 'int'. So the compiler is very picky here and the correct solution to make the code compile again and still let it show the exact same behavior like in Xcode 5.0 is to first cast to an integer type with a size that matches the one of a pointer and to then do a second cast to the int that we actually want: ids [i] = (int) (size_t)touch; If you need to keep the returned address, just keep it as void*. Example: int x=7, y=5; float z; z=x/y; /*Here the value of z is 1*/. If the destination type is bool, this is a boolean conversion (see below). Does a summoned creature play immediately after being summoned by a ready action? Identify those arcade games from a 1983 Brazilian music video. - the incident has nothing to do with me; can I use this this way? This example is noncompliant on an implementation where pointers are 64 bits and unsigned integers are 32 bits because the result of converting the 64-bit ptr cannot be represented in the 32-bit integer type. Is it possible to create a concave light? You use the address-of operator & to do that int x = 10; void *pointer = &x; And in the function you get the value of the pointer by using the dereference operator *: int y = * ( (int *) pointer); Share Improve this answer Follow edited Apr 15, 2013 at 13:58 answered Apr 15, 2013 at 13:53 Some programmer dude 394k 35 393 602 1 @Artelius: Which, presumably, is exactly what Joshua did: A C++ reinterpret cast will not solve the problem. "because the type "int" supports only -32768 ~ 32768" This is not true for any modern desktop or mobile OS or any OS that is targeted by cocos2d-x. Anw, the project still build and run normally when i use Xcode 5.0 with iOS 7.0. You are getting warnings due to casting a void* to a type of a different size. If pointers are 64 bits and ints are 32 bits, an int is too small to hold a pointer value. The problem just occur with Xcode 5.1. @Shahbaz you could but I will not suggest to a C newbie to use globals. The reinterpret_cast makes the int the size of a pointer and the warning will stop. Then i can continue compiling. @DietrichEpp can you explain what is race condition with using. The code ((void*)ptr + 1) does not work, because the compiler has no idea what size "void" is, and therefore doesn't know how many bytes to add. @jackdoe: It's a waste of human life to write code that "you may need in the future". long guarantees a pointer size on Linux on any machine. LLNL's tutorial is bad and they should feel bad. "clang" "-Ilib\libopenvswitch.a.p" "-Ilib" "-I..\lib" "-I." Properly casting a `void*` to an integer in C++ 24,193 Solution 1 I think using intptr_t is the correct intermediate here, since it's guaranteed to be large enough to contain the integral value of the void*, and once I have an integer value I can then truncate it without causing the compiler to complain.

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