Your first example is risky because you have to be very careful about the object lifetimes. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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 [.]) Example: int x=7, y=5; float z; z=x/y; /*Here the value of z is 1*/. How to correctly cast a pointer to int in a 64-bit application? 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. SCAN_PUT_ATTR(mask, ATTR, smask, FUNC); But the problem has still happened.
long guarantees a pointer size on Linux on any machine. 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. 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? Share Improve this answer Follow answered May 6, 2018 at 7:24 Rahul Find centralized, trusted content and collaborate around the technologies you use most. Thank you all for your feedback. 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! The following program casts a double to an int. 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. How to convert a factor to integer\numeric without loss of information? ncdu: What's going on with this second size column? *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 . (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. 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. There is absolutely not gurantee that sizeof(int) <= sizeof(void*). If any, how can the original function works without errors if we just ignore the warning. Making statements based on opinion; back them up with references or personal experience. 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. You are just making it bigger by tricking the compiler and the ABI. Once you manage to make this cast, then what?! 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. Already on GitHub? Sign in Implementation-dependent. } SCAN_END_SINGLE(ATTR) Please help me compile Chez Scheme. Basically its a better version of (void *)i. C/C++ , Cerror: cast to 'void *' from smaller integer type 'int'. A missing cast in the new fast > enumeration code. It generally takes place when in an expression more than one data type is present. I usually have all automatic conversion warnings effective when developing in C, and I use explicit casting in order to suppress a specific . Mutually exclusive execution using std::atomic? ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ If not, check the pointer size on your platform, define these typedefs accordingly yourself and use them. 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. This is why you got Error 1 C2036, from your post. To subscribe to this RSS feed, copy and paste this URL into your RSS reader.
Java Type Casting - W3Schools By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. *PATCH] platform/x86: hp-wmi: Fix cast to smaller integer type warning @ 2023-01-23 13:28 Hans de Goede 2023-01-23 13:56 ` Hans de Goede 0 siblings, 1 reply; 2+ messages in thread From: Hans de Goede @ 2023-01-23 13:28 UTC (permalink / raw) To: Mark Gross Cc: Hans de Goede, Andy Shevchenko, platform-driver-x86, kernel test robot Fix the following . If you cast an int pointer int, you might get back a different integer. Thus as a result it may be less error prone to generate a pointer dynamcially and use that. */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j; returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size); for (i=0, j=0; j
returnPtr[j] = (void *) (ptr + i); // <<< Compile Errors, Error1error C2036: 'void *' : unknown sizec:\temp\testone\lib\utils.c57, 2> returnPtr[j] = (void *) ((long*)ptr + i); // <<< No compile errors, 3> returnPtr[j] = (void *) ((char*)ptr + i); // <<< No compile errors. You can only do this if you use a synchronization primitive to ensure that there is no race condition. Implicit conversions - cppreference.com If your code has the chance to ever be ported to some platform where this doesn't hold, this won't work. You just need to suppress the warning, and this will do it: This may offend your sensibilities, but it's very short and has no race conditions (as you'd have if you used &i). void* to an array - C++ Forum - cplusplus.com What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? The problem is not with casting, but with the target type loosing half of the pointer. When is casting void pointer needed in C? Hence there is no loss in data. Type Casting Of Pointers in C - Computer Notes Or, they are all wrong. Why does flowing off the end of a non-void function without returning a value not produce a compiler error? The dynamic_cast<>operator provides a way to check the actual type of a pointer to a polymorphic class. ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' The result is implementation-defined and typically yields the numeric address of the byte in memory that the pointer pointers to. Use returnPtr[j] = (void *) ((long)ptr + i); ). However the actual code in question contains an explicit c-style cast to int. 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. If you really need such trickery, then consider one of dedicated types, which are intptr_t and uintptr_t. How create a simple program using threads in C? 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. GitHub Skip to content Product Solutions Open Source Pricing Sign in Sign up smadaminov / ovs-dpdk-meson-issues Public Notifications Fork 1 Star 1 Code Issues 66 Pull requests Actions Projects 1 Security Insights New issue How do I check if a string represents a number (float or int)? You may declare a const int variable and cast its reference to the void*. In the case of Widening Type Casting, the lower data type (having smaller size) is converted into the higher data type (having larger size). error: cast from pointer to smaller type 'unsigned int' loses Getting Command /bin/sh failed with exit code 65 Error with Xcode 5.1 . Netdev Archive on lore.kernel.org help / color / mirror / Atom feed * [mst-vhost:vhost 5/52] drivers/block/virtio_blk.c:539:21: warning: assignment to 'void *' from . error: cast from pointer to smaller type 'unsigned int' loses information. 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 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. In C (int)b is called an explicit conversion, i.e. itch" "-I..\include\windows" "-Iinclude" "-I..\include" "-I..\datapath-windows\include" "-IC:\PTHREADS-BUILT\include" "-Xclang" "-fcolor-diagnostics" "-pipe" See also this documentation.. From and Into are generally intended to be lossless, infalliable conversions.as on the other hand can discard data and lead to bugs in some situations, for example casting a u64 to a usize may truncate the value on a 32-bit host. 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]. Can we typecast void into int? - Quora Why is there a voltage on my HDMI and coaxial cables? What does casting to void* does when passing arguments to variadic functions? C / C++ Forums on Bytes. Asking for help, clarification, or responding to other answers. This is not even remotely "the correct answer". 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. The following behavior-changing defect reports were applied retroactively to previously published C++ standards. No idea how it amassed 27 upvotes?! How do I count the number of sentences in C using ". From the question I presume the OP does. If you are going to pass the address you typically need to exert some more control over the lifetime of the object. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. clang warnings in v1.42 Issue #265 ocornut/imgui GitHub Issues. How to get the error message from the error code returned by GetLastError()? How Intuit democratizes AI development across teams through reusability. Are there tables of wastage rates for different fruit and veg? Typically, long or unsigned long is . Implicit Type Conversion in C with Examples - GeeksforGeeks Since gcc compiles that you are performing arithmetic between void* and an int (1024). Making statements based on opinion; back them up with references or personal experience. Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin?). "clang" "-Ilib\libopenvswitch.a.p" "-Ilib" "-I..\lib" "-I." Using Kolmogorov complexity to measure difficulty of problems? If pointers are 64 bits and ints are 32 bits, an int is too small to hold a pointer value. ncdu: What's going on with this second size column? This will get you a pointer from a 32 bit offset: A function pointer is incompatible to void* (and any other non function pointer). There's no proper way to cast this to int in general case. Mutually exclusive execution using std::atomic? How to tell which packages are held back due to phased updates, Identify those arcade games from a 1983 Brazilian music video. What is the purpose of non-series Shimano components? void* -> integer -> void* rather than integer -> void* -> integer. and how to print the thread id of 2d array argument? 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. windows meson: cast to 'HANDLE' (aka 'void *') from smaller integer 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). How to make compiler not show int to void pointer cast warnings, incompatible pointer types assigning to 'void (*)(void *)' from 'int (int *)'. Pull requests. GitHub. Thanks. How to use Slater Type Orbitals as a basis functions in matrix method correctly? . 471,961 Members | 900 Online. 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). clang11 report error: cast to smaller integer type #82 - GitHub ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. Does a summoned creature play immediately after being summoned by a ready action? Pd = Pa; Similarly, Pc may be type cast to type int and assigned the value Pa. 1. FAILED: lib/libopenvswitch.a.p/odp-util.c.obj "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. 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. Error while setting app icon and launch image in xcode 5.1. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, error: cast from void* to int loses precision, cast to pointer from integer of different size, pthread code. The problem was there before, you just are being notified of it. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? Here is my code: I already tried (void*)M_TABLE_SIZE but then I get an error that I cannot use the * operator. I would create a structure and pass that as void* to pthread_create. In a 64bit build a pointer is 64bit (contrary to a 32bit build, where it is 32bit), while an int is 32bit, so this assignment stores a 64bit value in a 32bit storage, which may result in a loss of information. 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). Identify those arcade games from a 1983 Brazilian music video. reinterpret_cast conversion - cppreference.com 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; So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. Casting type int to const void* - C / C++ We have to pass address of the variable to the function because in function definition argument is pointer variable. 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;. Note the difference between the type casting of a variable and type casting of a pointer. How to Cast a void* ponter to a char without a warning? Whats the grammar of "For those whose stories they are"? ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] Any expression can be cast to type void (which means that the result of the expression is ignored), but it's not legal to cast an expression of type void to type int not least because the result of such a cast wouldn't make any sense. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? this way you won't get any warning. for (i=0, j=0; j