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 Remembering to delete the pointer after use so that we don't leak. Error while setting app icon and launch image in xcode 5.1. cast to 'void *' from smaller integer type 'int' Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? If int is no larger than pointer to void then one way to store the value is by simply copying the bytes: int i . Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Setting a buffer of char* with intermediate casting to int*. Put your define inside a bracket: without a problem. A missing cast in the new fast > enumeration code. Is pthread_join a must when using pthread in linux? I'm trying to create a void* from an int. sound/soc/codecs/tlv320aic32x4.c:1202:18: warning: cast to smaller For the second example you can make sure that sizeof(int) <= sizeof(void *) by using a static_assert -- this way at least you'll get a notice about it. Press question mark to learn the rest of the keyboard shortcuts. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? You cannot just cast the 32-bit variable to a pointer, because that pointer on a 64-bit machine is twice as long. He should pass the address of the integer, the thread should get that address, Note: This is only appropriate is you cast the. unsigned long call_fn = (unsigned long)FUNC; Unless you have a valid address at that value, you are going to invoke undefined behaviour when try to use that pointer. You can also convert values from one type to another explicitly using the cast operator (see Chapter 5 ): ( type_name) expression In the following example, the cast operator causes the division of one integer variable by another to be performed as a floating-point operation: int sum = 22, count = 5; double mean = (double)sum / count; (i.e. Replacing broken pins/legs on a DIP IC package, AC Op-amp integrator with DC Gain Control in LTspice. Use returnPtr[j] = (void *) ((long)ptr + i); ). tialized" "-Wno-format" "-Wno-incompatible-pointer-types" "-Werror" "-dM" "-U_MSC_VER" "-D_TIMESPEC_DEFINED" "-D_CRT_NONSTDC_NO_DEPRECATE -D_CRT_SECURE_NO_WA That could create all kinds of trouble. Use of Void pointers in C programming language 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. 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 will only compile if the destination type is long enough. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. Using indicator constraint with two variables. This is why you got Error 1 C2036, from your post. We have to pass address of the variable to the function because in function definition argument is pointer variable. The high-order 9 bits of the number are used to hold a flag value, and the result is converted back into a pointer. Casting type int to const void* - C / C++ /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. And, most of these will not even work on gcc4. Implementation-dependent. a cast of which the programmer should be aware of what (s)he is doing. What is the point of Thrower's Bandolier? The following behavior-changing defect reports were applied retroactively to previously published C++ standards. : iPhone Retina 4-inch 64-bit) is selected. Re: [PATCH, PR 53001] Re: Patch to split out new warning flag for Does melting sea ices rises global sea level? Why is there a voltage on my HDMI and coaxial cables? ncdu: What's going on with this second size column? To access the object value, use the * dereference operator: int * p; assert (p == null ); p = new int (5); assert (p != null ); assert (*p == 5); (*p)++; assert (*p == 6); If a pointer contains a null value, it is not pointing to a valid object. -1, Uggh. [that could be a TODO - not to delay solving the ICE]. C/C++ , Cerror: cast to 'void *' from smaller integer type 'int'. For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. If you do this, you have the thread reference a value that (hopefully still) lives in some other thread. Making statements based on opinion; back them up with references or personal experience. To avoid truncating your pointer, cast it to a type of identical size. C - Type Casting - tutorialspoint.com Then I build my project, I get the error "Cast from pointer to smaller type 'int' loses information" in EAGLView.mm file (line 408) when 64-bit simulators (e.g. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ this way you won't get any warning. As for the stack, I've written a few libraries using pthreds, thus I don't agree that what you describe "is quite often the case". Sign up for a free GitHub account to open an issue and contact its maintainers and the community. 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). Click to see the query in the CodeQL repository. You are getting warnings due to casting a void* to a type of a different size. @DavidHeffernan I rephrased that sentence a little. 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 Floating-point conversions In both cases, converting the pointer to an integer type that's too small to represent all pointer values is a bug. @DavidHeffernan, sane thread APIs wouldn't send integral data to the thread procedures, they would send pointers. I have a two functions, one that returns an int, and one that takes a const void* as an argument. How to correctly cast a pointer to int in a 64-bit application? Casting type void to uint8_t - Arduino Forum Yeah, the tutorial is doing it wrong. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? Casting arguments inside the function is a lot safer. This is an old C callback mechanism so you can't change that. 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. It's always a good practice to put your #define's in brackets to avoid such surprise. @LearnCocos2D: so, how can i "overcome" the error without editing any not-my-code or in-library-file lines? What video game is Charlie playing in Poker Face S01E07? "I think what you should do is actually pass the address of the variable to the function" Not necessarily. You are just making it bigger by tricking the compiler and the ABI. I'm using cocos2d-x-2.2.2. @BlueMoon Thanks a lot! This page has been accessed 1,655,678 times. For the Nozomi from Shinagawa to Osaka, say on a Saturday afternoon, would tickets/seats typically be available - or would you need to book? How to notate a grace note at the start of a bar with lilypond? C / C++ Forums on Bytes. It is done by the compiler on its own, without any external trigger from the user. How to use Slater Type Orbitals as a basis functions in matrix method correctly? should we also have a diagnostic for the (presumed) user error? pthread passes the argument as a void*. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, @Dinesh: could you please 1) show us those. If your standard library (even if it is not C99) happens to provide these types - use them. void* -> integer -> void* rather than integer -> void* -> integer. And when assigning to a void pointer, all type information is lost. Narrowing Casting (manually) - converting a larger type to a . I think the solution 3> should be the correct one. You can use a 64 bits integer instead howerver I usually use a function with the right prototype and I cast the function type : to your account, [87/252] Compiling C object lib/libopenvswitch.a.p/odp-util.c.obj Evaluate integer expressions in a larger size before comparing or assigning to that size.Note that (time_+t)-1 also complies with INT31-C-EX3. ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' To learn more, see our tips on writing great answers. Example: int x=7, y=5; float z; z=x/y; /*Here the value of z is 1*/. What is the difference between const int*, const int * const, and int const *? How to use Slater Type Orbitals as a basis functions in matrix method correctly? } SCAN_END_SINGLE(ATTR) Only the following conversions can be done with static_cast, except when such conversions would cast away constness or volatility. Converting a pointer to an integer whose result cannot represented in the integer type is undefined behavior is C and prohibited in C++. SCAN_PUT(ATTR, NULL); To perform a cast, specify the type that you are casting to in parentheses in front of the value or variable to be converted. ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' Don't do that. Instead of using a long cast, you should cast to size_t. [PATCH] platform/x86: hp-wmi: Fix cast to smaller integer type warning In such a case the programmer can use a void pointer to point to the location of the unknown data type. Use #include to define it. 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. 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. However even though their types are different, the address is going to be the same. Bulk update symbol size units from mm to map units in rule-based symbology. Fork 63. Visit Microsoft Q&A to post new questions. For a fairly recent compiler (that supports C99) you should not store or represent address as plain int value. 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. Thanks for contributing an answer to Stack Overflow! There is absolutely not gurantee that sizeof(int) <= sizeof(void*). Basically its a better version of (void *)i. For example, if you want to store a 'long' value into a simple integer then you can type cast 'long' to 'int'. Even if you are compiling your program for a 32-bit computer, you should fix your code to remove these warnings, to ensure your code is easily portable to 64-bit. 10) A prvalue of type pointer to void (possibly cv-qualified) can be converted to pointer to any object type. The int data type is the primary integer data type in SQL Server. Losing bytes like thisis called 'truncation', and that's what the first warning is telling you. ", "? And then assign it to the double variable. Windows has 32 bit long only on 64 bit as well. 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. A cast converts an object or value from one type to another. 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. Thanks. 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" (. 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! Asking for help, clarification, or responding to other answers. 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. How to use Slater Type Orbitals as a basis functions in matrix method correctly? Why is this sentence from The Great Gatsby grammatical? Issues. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Find centralized, trusted content and collaborate around the technologies you use most. Passing arguments to pthread_create - invalid conversion from void(*)() to void(*)(void*). 471,961 Members | 900 Online. I have the following function and when I compile it under VS.NET 2005, the following compile warnings show up: Warning1warning C4311: 'type cast' : pointer truncation from 'void *' to 'long'c:\temp\testone\lib\utils.c56Warning2warning C4312: 'type cast' : conversion from 'unsigned long' to 'void *' of greater sizec:\temp\testone\lib\utils.c56, Code Snippet
Next, when doing pointer arithmetic, the addition operation will use the pointer's type to determine how many bytes to add to it when incrementing it. What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. Since all pointers on 64-bit Windows are 64 bits, you are growing the data size from 32 bits backto 64 bits. Remarks. Usually that means the pointer is allocated with. Otherwise, if the original pointer value points to an object a, and there is an object b of the . Safe downcast may be done with dynamic_cast. casting from int to void* and back to int. How do I force make/GCC to show me the commands? Type Casting Of Pointers in C - Computer Notes A nit: in your version, the cast to void * is unnecessary. Before I update Xcode, my project still can build and run normally with all devices. So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. Now, what happens when I run it with the thread sanitizer? You should perform type conversion based on 64bit build system because the type "int" supports only -32768 ~ 32768. Can Martian regolith be easily melted with microwaves? This is memory reinterpretation - a completely unacceptable way to do what the OP is trying to do. The 32 remaining bits stored inside int are insufficient to reconstruct a pointer to the thread function. As was pointed out by Martin, this presumes that sizeof(void*)>=sizeof(int). windows meson: cast to 'HANDLE' (aka 'void *') from smaller integer 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. SCAN_PUT_ATTR(mask, ATTR, smask, FUNC); */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j;
This is what the second warning is telling you. You could use this code, and it would do the same thing as casting ptr to (char*). Whats the grammar of "For those whose stories they are"? Thanks for pointing that out. rev2023.3.3.43278. This is not a conversion at all. For example, the main thread could wait for all of the other threads to end before terminating. If you preorder a special airline meal (e.g. In C (int)b is called an explicit conversion, i.e. vegan) just to try it, does this inconvenience the caterers and staff? But then you need to cast your arguments inside your thread function which is quite unsafe cf. Did i have to face to unexpected runtime issues, i guess not, i've found another discussion on this -. rev2023.3.3.43278. Typically, long or unsigned long is . How to correctly cast a pointer to int in a 64-bit application? It's an int type guaranteed to be big enough to contain a pointer. Casting int to void* : r/C_Programming - reddit c - Cast int to void* - Stack Overflow Bulk update symbol size units from mm to map units in rule-based symbology. Recovering from a blunder I made while emailing a professor. error: comparison between pointer and integer ('int' and 'string' (aka 'char *')), CS50 Caesar program is working but check50 says it isn't. reinterpret_cast<void *>(42)). Half your pointer will be garbage. ^~~~~~~~~~~~~~~~~~~~ For integer casts in specific, using into() signals that . 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. windows meson: cast to smaller integer type 'unsigned long' from 'void *'. 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). 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. property that any valid pointer to void can be converted to this type, If your standard library (even if it is not C99) happens to provide these types - use them. Therefore it is perfectly valid for the compiler to throw an error for a line like. The result is the same as implicit conversion from the enum's underlying type to the destination type. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, "what happen when typcating normal variable to void* or any pointer variable?" Infact I know several systems where that does not hold. I have looked around and can't seem to find any information on how to do this. If this is the data to a thread procedure, then you quite commonly want to pass by value. that any valid pointer to void can be converted to this type, then By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Find centralized, trusted content and collaborate around the technologies you use most. ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); How to convert a factor to integer\numeric without loss of information? returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size);
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. There's no proper way to cast this to int in general case. So,solution #3 works just fine. Connect and share knowledge within a single location that is structured and easy to search. error: cast from pointer to smaller type 'unsigned int' loses information. arrays - I get the error: "cast to smaller integer type 'int' from
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