cast to void *' from smaller integer type 'int

You think by casting it here that you are avoiding the problem! vegan) just to try it, does this inconvenience the caterers and staff? In 64-bit programs, the size of the pointer is 64 bits, and cannot be put into the int type, which remains 32-bit in almost all systems. 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). Star 675. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Wrong. use $(ARCHS_STANDARD_32_BIT) at Architecture instead of $(ARCHS_STANDARD). SCAN_PUT(ATTR, NULL); Referring to N1570 7.20.1.4/p1 (Integer types capable of holding object pointers): The following type designates a signed integer type with the property 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. should we also have a diagnostic for the (presumed) user error? LLNL's tutorial is bad and they should feel bad. What is the correct method to cast an int to a void*? Why is there a voltage on my HDMI and coaxial cables? C99 defines the types "intptr_t" and "uintptr_t" which do . Returns a value of type new-type. with ids being an array of ints and touch being a pointer. There is no "correct" way to store a 64-bit pointer in an 32-bit integer. lexborisov Modest Public. Typically, long or unsigned long is . Casting an open pointer to other pointer types and casting other pointer types to an open pointer does not result in a compile time error. @DavidHeffernan I rephrased that sentence a little. Now, what happens when I run it with the thread sanitizer? Mutually exclusive execution using std::atomic? Find centralized, trusted content and collaborate around the technologies you use most. 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. Connect and share knowledge within a single location that is structured and easy to search. If not, check the pointer size on your platform, define these typedefs accordingly yourself and use them. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. RNINGS" "-D_CRT_SECURE_NO_DEPRECATE" -MD -MQ lib/libopenvswitch.a.p/odp-util.c.obj -MF "lib\libopenvswitch.a.p\odp-util.c.obj.d" -o lib/libopenvswitch.a.p/od By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Infact I know several systems where that does not hold. Functions return bigint only if the parameter expression is a bigint data type. But then you need to cast your arguments inside your thread function which is quite unsafe cf. 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. LLNL's tutorial is bad and they should feel bad. But assuming that it is, as long as the caller and the callee agree, you can do that sort of thing. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. On all of them int is 32bit, not 16bit. I get the error: "cast to smaller integer type 'int' from 'string' (aka 'char *')" referencing line of code: while (isalpha(residents[i].name) == 0), How Intuit democratizes AI development across teams through reusability. Just want to point out that the purpose of threads is, +1 absolutely true, but if you take you time to write struct {}, you can save a lot of troubles in the future when you want to receive/send more data then just an int. Why do academics stay as adjuncts for years rather than move around? reinterpret_cast is a type of casting operator used in C++. The compiler issues the "cast from integer to pointer of different size" warning whenever the value of an integer is converted to a pointer, especially when the memory allocated to a pointer is smaller than the memory allocated to an integer data type. What you do here is undefined behavior, and undefined behavior of very practical sort. Acidity of alcohols and basicity of amines. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The difference between a and &a is the type. Asking for help, clarification, or responding to other answers. A missing cast in the new fast > enumeration code. That could create all kinds of trouble. Thanks for contributing an answer to Stack Overflow! you can pass the int value as void pointer like (void *)&n where n is integer, and in the function accept void pointer as parameter like void foo(void *n);and finally inside the function convert void pointer to int like, int num = *(int *)n;. pthread passes the argument as a void*. 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. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? 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. So,solution #3 works just fine. Why did Ukraine abstain from the UNHRC vote on China? Thank you all for your feedback. (int) pthread_self() 64int48intuintptr_t (unsigned int) Sign up for a free GitHub account to open an issue and contact its maintainers and the community. What is the purpose of non-series Shimano components? You are right! That's probably going to be true for most platforms you will ever encounter, but it's not a guarantee; it's implementation-dependent. A cast specifies a conversion from one type to another. Therefore, you need to change it to long long instead of long in windows for 64 bits. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. You need to pass an actual pointer. "I think what you should do is actually pass the address of the variable to the function" Not necessarily. Even though what you say regarding the lifetime of the object is true, integral types are too limited for a generic API. There exist two main syntaxes for generic type-casting: functional and c-like: 1 2 3 4 double x = 10.3; int y; y = int (x); // functional notation y = (int) x; // c-like cast notation The functionality of these generic forms of type-casting is enough for most needs with fundamental data types. Thanks for pointing that out. While working with Threads in C, I'm facing the warning, "warning: cast to pointer from integer of different size". How to use Slater Type Orbitals as a basis functions in matrix method correctly? 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). "-D_FILE_OFFSET_BITS=64" "-Wall" "-Winvalid-pch" "-g" "-Wthread-safety" "-Wno-microsoft-enum-forward-reference" "-Wno-unused-function" "-Wno-sometimes-unini If the source type is bool, the value false is converted to zero and the value true is converted to the value one of the destination type (note that if the destination type is int, this is an integer promotion, not an integer conversion). Does a summoned creature play immediately after being summoned by a ready action? Windows has 32 bit long only on 64 bit as well. ncdu: What's going on with this second size column? This will only compile if the destination type is long enough. Converts between types using a combination of implicit and user-defined conversions. How can this new ban on drag possibly be considered constitutional? ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. unsigned long call_fn = (unsigned long)FUNC; However even though their types are different, the address is going to be the same. Making statements based on opinion; back them up with references or personal experience. So you could do this: Note: As sbi points out this would require a change on the OP call to create the thread. Did i have to face to unexpected runtime issues, i guess not, i've found another discussion on this -. The correct answer is, if one does not mind losing data precision. Asking for help, clarification, or responding to other answers. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. This is memory reinterpretation - a completely unacceptable way to do what the OP is trying to do. This is not a conversion at all. Basically its a better version of (void *)i. (i.e. 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. In Java, there are two types of casting: Widening Casting (automatically) - converting a smaller type to a larger type size. how to cascade 2d int array to 2d void pointer array? If you write ((char*)ptr + 1), it will advance the pointer 1 byte, because a "char" is 1 byte. 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). GitHub. It is easier to understand and write than any other assembly language. 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. 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; Just edited. How do I work around the GCC "error: cast from SourceLocation* to int loses precision" error when compiling cmockery.c? The point is (probably) that the value passed to the thread is an integer value, not really a 'void *'. whether it was an actual problem is a different matter though. what happens when we typecast normal variable to void* or any pointer variable? (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 AC Op-amp integrator with DC Gain Control in LTspice. Why is this sentence from The Great Gatsby grammatical? But I don't want to edit code in "EAGLView.mm" because it's a "library file". Visit Microsoft Q&A to post new questions. You are getting warnings due to casting a void* to a type of a different size. (Also, check out how it prints "5" twice), passing a unique pointer to each thread wont race, and you can get/save any kind of information in the th struct. You need to cast the void* pointer to a char* pointer - and then dereference that char* pointer to give you the char that it points to! Connect and share knowledge within a single location that is structured and easy to search. 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. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. This is not even remotely "the correct answer". Is a PhD visitor considered as a visiting scholar. Asking for help, clarification, or responding to other answers. In C (int)b is called an explicit conversion, i.e. And then assign it to the double variable. A sane compiler may throw a warning on lines like this but by no way it should throw an error, because this code is NOT wrong, it is just potentially error-prone, but can be perfectly valid. Does melting sea ices rises global sea level? It was derived from the BCPL, and the name of the b language is possibly from the BCPL contraction. When is casting void pointer needed in C? Here, the Java first converts the int type data into the double type. ../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 ^~~~~~~~~~~~~~~~~~~~ Remembering to delete the pointer after use so that we don't leak. You are just making it bigger by tricking the compiler and the ABI. privacy statement. This solution is in accordance with INT18-C. If you do this, you have the thread reference a value that (hopefully still) lives in some other thread. Apparently the clang version in Xcode 5.1 and above is more strict about potential 32bit vs. 64 bit incompatibilities in source code than older clang versions have been. You may declare a const int variable and cast its reference to the void*. windows meson: cast to smaller integer type 'unsigned long' from 'void *'. pthread create managing values generated in function (in c), Establishing TCP socket connection between PHP client and C server on Ubuntu. Issues. Use #include to define it. But, sure, in that specific case you can pass a local variable address, type casting integer to void* [duplicate]. How to correctly cast a pointer to int in a 64-bit application? Changing the type of ids would be the cleanest solution, but I decided against it when being confronted with this issue myself, as it only introduced a lot of issues with other code that is relying on ids being an int-array. How Intuit democratizes AI development across teams through reusability. ../lib/odp-util.c:5601:9: note: expanded from macro 'SCAN_PUT' This is flat out wrong. A cast converts an object or value from one type to another. What is the point of Thrower's Bandolier? This page was last modified on 12 February 2023, at 18:25. Getting Command /bin/sh failed with exit code 65 Error with Xcode 5.1 . In the first example, the variable c1 of the char type is converted to a temporary variable of the int type, because the second operand in the division operation, the constant 2, is of the higher type int. So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? Instead of using a long cast, you should cast to size_t. What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. In such a case the programmer can use a void pointer to point to the location of the unknown data type. ERROR: incompatible integer to pointer conversion assigning to 'string' (aka 'char *') from 'int', error: cast to 'string' (aka 'char *') from smaller integer type 'int' [-Werror,-Wint-to-pointer-cast], error: incompatible integer to pointer conversion assigning to 'string' (aka 'char *') from 'int' C, warning: initialization of 'unsigned char' from 'uint8_t *' {aka 'unsigned char *'} makes integer from pointer without a cast [-Wint-conversion], Minimising the environmental effects of my dyson brain. -1, Uggh. No idea how it amassed 27 upvotes?! returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size); 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. Find centralized, trusted content and collaborate around the technologies you use most. Linear regulator thermal information missing in datasheet. "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. 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. *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 . 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. Connect and share knowledge within a single location that is structured and easy to search. How to use Slater Type Orbitals as a basis functions in matrix method correctly? As a result of the integer division 3/2 we get the value 1, which is of the int type. 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. How do I force make/GCC to show me the commands? A nit: in your version, the cast to void * is unnecessary. So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. If you really need such trickery, then consider one of dedicated types, which are intptr_t and uintptr_t. (int*)Pc = pa; After the execution of the above code all the three pointers, i.e., Pa, Pd, and Pc, point to the value 150. This forum has migrated to Microsoft Q&A. 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. 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. What is the difference between const int*, const int * const, and int const *? From what I read about casting in the C11 standard, my feeling is, that it is arguable to emit a warning on an explicit conversion. Whats the grammar of "For those whose stories they are"? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. equal to the original pointer: First you are using a define, which is not a variable. The pointer doesn't actually point to anything, but it's the result of an earlier cast from an integer to a pointer (e.g. Using an integer address (like &x) is probably wrong, indeed each modification you will execute on x will affect the pass behaviour. Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin? even though the compiler doesn't know you only ever pass myFcn to pthread_create in conjunction with an integer. Find centralized, trusted content and collaborate around the technologies you use most. Don't do that. And you can't pass a pointer to a stack based object from the other thread as it may no longer be valid. Do new devs get fired if they can't solve a certain bug? Keep in mind that thrArg should exist till the myFcn() uses it. The bigint data type is intended for use when integer values might exceed the range that is supported by the int data type.. bigint fits between smallmoney and int in the data type precedence chart.. Once you manage to make this cast, then what?! My code is all over the place now but I appreciate you all helping me on my journey to mastery! 7.1 New Cast Operations The C++ standard defines new cast operations that provide finer control than previous cast operations. 1. By clicking Sign up for GitHub, you agree to our terms of service and 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 explicit cast clearly tells the compiler "Shut up, I know that this code does not look correct, but I do know what I am doing". 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. To be honest, I think, clang is too restrictive here. ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' From that point on, you are dealing with 32 bits. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. } SCAN_END_SINGLE(ATTR) 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. If that happens soon after the call to pthread_create() then you have a race condition, because there's a chance that the thread will attempt to read x's value after it's life has ended, which invokes undefined behavior. Not the answer you're looking for? Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? The value of float variable is= 37.75. Here is some piece of code where that error occur: /cocos2d-x-2.2.2/cocos2dx/platform/ios/EAGLView.mm:408:18: Cast from pointer to smaller type 'int' loses information. And when assigning to a void pointer, all type information is lost. Before I update Xcode, my project still can build and run normally with all devices. Have a question about this project? To cast such pointers to 32-bit types and vice versa special functions are used: void * Handle64ToHandle ( const void * POINTER_64 h ) void * POINTER_64 HandleToHandle64 ( const void *h ) long HandleToLong ( const void *h ) unsigned long HandleToUlong ( const void *h ) Replacing broken pins/legs on a DIP IC package, How to handle a hobby that makes income in US. Why do small African island nations perform better than African continental nations, considering democracy and human development? The following program casts a double to an int. - the incident has nothing to do with me; can I use this this way? 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. Bulk update symbol size units from mm to map units in rule-based symbology. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. rev2023.3.3.43278. A void pointer can be really useful if the programmer is not sure about the data type of data inputted by the end user. what does it mean to convert int to void* or vice versa? I would create a structure and pass that as void* to pthread_create. Your first example is risky because you have to be very careful about the object lifetimes. casting from int to void* and back to int. If your standard library (even if it is not C99) happens to provide these types - use them. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Xcode 5 and iOS 7: Architecture and Valid architectures, xcode build error: Semantic issue cast from pointer to smaller type 'int' loses information, Issues in handling touches on subviews(uiviews) in UIScrollView, Architecture linking error after Xcode 5.1 upgrade, iOS 7.1 gives error after updating to Xcode 5.1, Linker error in Xcode 5.1 with cocos2d-x 3 beta 2. */ >> -bool >> +enum conversion_safety >> unsafe_conversion_p (tree type, tree expr, bool . Converting one datatype into another is known as type casting or, type-conversion. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? This is a fine way to pass integers to new pthreads, if that is what you need. ", "!"? How to notate a grace note at the start of a bar with lilypond? For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. Using Kolmogorov complexity to measure difficulty of problems? STR34-C. I usually have all automatic conversion warnings effective when developing in C, and I use explicit casting in order to suppress a specific . How can this new ban on drag possibly be considered constitutional? What happens if you typecast as unsigned first? @kshegunov said in Number Type Cast: const void * x; int y = int (x); compiles just fine. Why does Mister Mxyzptlk need to have a weakness in the comics? If you are planning to use pthreads and you are planning to pass the pass function to pthread_create, you have to malloc/free the arguments you are planning to use (even if the threaded function just need a single int). 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. I am compiling this program in linux gcc compiler.. How do I align things in the following tabular environment? Note that it's not guaranteed that casting an, Generally this kind of type casting does not lead to any concern as long as the addresses are encoded using the same length as the "variable type" (. But the problem has still happened. Making statements based on opinion; back them up with references or personal experience.

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