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. I have a two functions, one that returns an int, and one that takes a const void* as an argument. Using indicator constraint with two variables. vegan) just to try it, does this inconvenience the caterers and staff? Can anybody explain how to pass an integer to a function which receives (void * ) as a parameter? */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. 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. 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; 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. This is why you got Error 1 C2036, from your post. SCAN_PUT_ATTR(mask, ATTR, smask, FUNC); To learn more, see our tips on writing great answers. Java Type Casting. Replacing broken pins/legs on a DIP IC package, How to handle a hobby that makes income in US. Once you manage to make this cast, then what?! It's always a good practice to put your #define's in brackets to avoid such surprise. I am compiling this program in linux gcc compiler.. Basically its a better version of (void *)i. *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 really need such trickery, then consider one of dedicated types, which are intptr_t and uintptr_t. Does ZnSO4 + H2 at high pressure reverses to Zn + H2SO4? I think the solution 3> should be the correct one. Why is this sentence from The Great Gatsby grammatical? SCAN_PUT_ATTR(key, ATTR, skey, FUNC); Api says this is how i should create thread: So if I want to pass an int what I think I should do is: The second example assumes that a pointer is wide enough to store an int. But then you need to cast your arguments inside your thread function which is quite unsafe cf. ncdu: What's going on with this second size column? should we also have a diagnostic for the (presumed) user error? This will get you a pointer from a 32 bit offset: A function pointer is incompatible to void* (and any other non function pointer). 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 ) @Artelius: Which, presumably, is exactly what Joshua did: A C++ reinterpret cast will not solve the problem. This is memory reinterpretation - a completely unacceptable way to do what the OP is trying to do. Please tell me error: cast from 'void*' to 'int' loses precision, How Intuit democratizes AI development across teams through reusability. Surely the solution is to change the type of ids from int to type that is sufficiently large to hold a pointer. As was pointed out by Martin, this presumes that sizeof(void*)>=sizeof(int). ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ } SCAN_END_SINGLE(ATTR) On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. Identify those arcade games from a 1983 Brazilian music video, Relation between transaction data and transaction id, The difference between the phonemes /p/ and /b/ in Japanese. : iPhone Retina 4-inch 64-bit) is selected. Why do small African island nations perform better than African continental nations, considering democracy and human development? ", "!"? rev2023.3.3.43278. How to use Slater Type Orbitals as a basis functions in matrix method correctly? Find centralized, trusted content and collaborate around the technologies you use most. Passing arguments to pthread_create - invalid conversion from void(*)() to void(*)(void*). You are getting warnings due to casting a void* to a type of a different size. 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. A missing cast in the new fast > enumeration code. If the destination type is bool, this is a boolean conversion (see below). [] ExplanatioUnlike static_cast, but like const_cast, the reinterpret_cast expression does not compile to any CPU instructions (except when converting between integers and pointers or on obscure architectures where pointer representation depends on its type). Thank you all for your feedback. If your standard library (even if it is not C99) happens to provide these types - use them. 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. Are there tables of wastage rates for different fruit and veg? ../lib/odp-util.c:5603:13: note: expanded from macro 'SCAN_PUT' You can convert the values from one type to another explicitly using the cast operator as follows (type_name) expression This will only compile if the destination type is long enough. static_cast on the other hand should deny your stripping away the const qualifier. to the original pointer: The following type designates an unsigned integer type with the Making statements based on opinion; back them up with references or personal experience. Windows has 32 bit long only on 64 bit as well. The problem was there before, you just are being notified of it. The int data type is the primary integer data type in SQL Server. 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. And, most of these will not even work on gcc4. privacy statement. An open (void) pointer can hold a pointer of any type. A long long would not work for 32bit systems and a long would not work for 64 bit Windows (while 64bit Unix and Unix-like systems like OS X use the LP64 data model, in which a long is 64bit, 64bit Windows uses the LLP64 data model, in which a long has a size of 32bit (http://en.wikipedia.org/wiki/64-bit_computing#64-bit_data_models)). "After the incident", I started to be more careful not to trip over things. 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. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Why does setupterm terminate the program? Please unaccept the answer you have chosen as it is wrong (as the comments below it say) and will lead to bugs. Projects. Now, what happens when I run it with the thread sanitizer? Why do academics stay as adjuncts for years rather than move around? You cannot just cast the 32-bit variable to a pointer, because that pointer on a 64-bit machine is twice as long. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Here is my code: I already tried (void*)M_TABLE_SIZE but then I get an error that I cannot use the * operator. Casting int to void* loses precision, and what is the solution in required cases, c++: cast from "const variable*" to "uint32" loses precision, Recovering from a blunder I made while emailing a professor, Relation between transaction data and transaction id. 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). this way you won't get any warning. AC Op-amp integrator with DC Gain Control in LTspice. a is of type int[4], which can be implicitly cast to int* (ie, a pointer to an int) &a is of type int(*)[4] (ie: a pointer to an array of 4 ints). 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". even though the compiler doesn't know you only ever pass myFcn to pthread_create in conjunction with an integer. @DavidHeffernan I rephrased that sentence a little. It is done by the compiler on its own, without any external trigger from the user. How to notate a grace note at the start of a bar with lilypond? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Asking for help, clarification, or responding to other answers. In such a case the programmer can use a void pointer to point to the location of the unknown data type. Not the answer you're looking for? cast to 'double *' from smaller integer type 'unsigned int' The C compiler is gcc, clang version 3.9.1, target aarch64--linux-android, thread model posix. Notifications. The only exception is exotic systems with the SILP64 data model, where the size of int is also 64 bits. To perform a cast, specify the type that you are casting to in parentheses in front of the value or variable to be converted. @Xax: Here's a fixed version, without the race condition: gist.github.com/depp/241d6f839b799042c409, gist.github.com/depp/3f04508a88a114734195, How Intuit democratizes AI development across teams through reusability. Not the answer you're looking for? 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 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. SCAN_PUT(ATTR, NULL); The reinterpret_cast makes the int the size of a pointer and the warning will stop. How do I check if a string represents a number (float or int)? Making statements based on opinion; back them up with references or personal experience. Thanks Jonathan, I was thinking about my answer in another thread: AraK is correct, passing integers a pointers are not necessarily interchangeable. pthread create managing values generated in function (in c), Establishing TCP socket connection between PHP client and C server on Ubuntu. Based on the design of this function, which modification is right. to your account, [87/252] Compiling C object lib/libopenvswitch.a.p/odp-util.c.obj You may declare a const int variable and cast its reference to the void*. However, I believe that even if the define was for the "65536", it would not be what @kaetzacoatl wanted. He should pass the address of the integer, the thread should get that address, Note: This is only appropriate is you cast the. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. There's no proper way to cast this to int in general case. Identify those arcade games from a 1983 Brazilian music video. how to cascade 2d int array to 2d void pointer array? If the object expression refers or points to is actually a base class subobject of an object of type D, the result refers to the enclosing object of type D. Otherwise, the behavior is undefined: When the target type is bool (possibly cv-qualified), the result is false if the original value is zero and true for all other values. Find centralized, trusted content and collaborate around the technologies you use most. No idea how it amassed 27 upvotes?! Here, the Java first converts the int type data into the double type. Offline ImPer Westermark over 11 years ago in reply to Andy Neil Except that you sometimes stores an integer in the pointer itself. long guarantees a pointer size on Linux on any machine. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. The calculated expression consists of two operations. pthread passes the argument as a void*. A nit: in your version, the cast to void * is unnecessary. You think by casting it here that you are avoiding the problem! Thanks for contributing an answer to Stack Overflow! But I'm nitpicking .. It's an int type guaranteed to be big enough to contain a pointer. Update: Today, i download the latest version of cocos2d-x (cocos2d-x 2.2.3). What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? Bulk update symbol size units from mm to map units in rule-based symbology. In such condition type conversion (type promotion) takes place to avoid loss of data. "-I.." "-Iinclude\openflow" "-I..\include\openflow" "-Iinclude\openvswitch" "-I..\include\openvsw Why is there a voltage on my HDMI and coaxial cables? Keep in mind that thrArg should exist till the myFcn() uses it. 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 C99 defines the types "intptr_t" and "uintptr_t" which do . If any, how can the original function works without errors if we just ignore the warning. Press question mark to learn the rest of the keyboard shortcuts. I guess the other important fact is that the cast operator has higher precedence that the multiplication operator. You are correct, but cocos actually only uses that address as a unique id. Converts between types using a combination of implicit and user-defined conversions. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? When is casting void pointer needed in C? Yesterday, I updated Xcode to the newest version (5.1 (5B130a)) to compatible with iOS 7.1. ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' There's no proper way to cast this to int in general case. Have a question about this project? Does a summoned creature play immediately after being summoned by a ready action? The cast back to int * is not, though. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? You are just making it bigger by tricking the compiler and the ABI. How to convert a factor to integer\numeric without loss of information? Losing bytes like thisis called 'truncation', and that's what the first warning is telling you. Therefore, you need to change it to long long instead of long in windows for 64 bits. For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. The result is implementation-defined and typically yields the numeric address of the byte in memory that the pointer pointers to. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. 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! Pd = Pa; Similarly, Pc may be type cast to type int and assigned the value Pa. 1. If you cast an int pointer int, you might get back a different integer. And when assigning to a void pointer, all type information is lost. @BlueMoon Thanks a lot! STR34-C. rev2023.3.3.43278. "-D_FILE_OFFSET_BITS=64" "-Wall" "-Winvalid-pch" "-g" "-Wthread-safety" "-Wno-microsoft-enum-forward-reference" "-Wno-unused-function" "-Wno-sometimes-unini @Shahbaz you could but I will not suggest to a C newbie to use globals. What is the purpose of non-series Shimano components? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size);
/** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. Disconnect between goals and daily tasksIs it me, or the industry? Such pointers can be stored in 32-bit data types (for instance, int, DWORD). Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Using Kolmogorov complexity to measure difficulty of problems? My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? 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. The subreddit for the C programming language, Press J to jump to the feed. Disconnect between goals and daily tasksIs it me, or the industry? Again, all of the answers above missed the point badly. rev2023.3.3.43278. 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 Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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. ^~~~~~~~~~~~~~~~~~~~~ This is flat out wrong. Where does this (supposedly) Gibson quote come from? @kshegunov said in Number Type Cast: const void * x; int y = int (x); compiles just fine. ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] If we want to get the exact value of 7/5 then we need explicit casting from int to float: Example: int x=7, y=5; The preprocessor will replace your code by this: This is unlikely what you are trying to do. Otherwise, if the original pointer value points to an object a, and there is an object b of the . error: cast from pointer to smaller type 'unsigned int' loses information. Example: int x=7, y=5; float z; z=x/y; /*Here the value of z is 1*/. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? However, you are also casting the result of this operation to (void*). Error while setting app icon and launch image in xcode 5.1. 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;. */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j;
*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 . ^~~~~~~~~~~~~~~~~~~ Alternatively, if you choose to castthe ptr variableto (size_t) instead, then you don't need to worry about the pointer typeanymore. Connect and share knowledge within a single location that is structured and easy to search. 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). This is known as implicit type casting or type promotion, compiler automatically converts smaller data type to larger data type. Put your define inside a bracket: without a problem. Does Counterspell prevent from any further spells being cast on a given turn? (int) pthread_self() 64int48intuintptr_t (unsigned int) But gcc always give me a warning, that i cannot cast an int to a void*. LLNL's tutorial is bad and they should feel bad. B language was designed to develop . Why is there a voltage on my HDMI and coaxial cables? 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). Before I update Xcode, my project still can build and run normally with all devices. 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. It is commonly called a pointer to T and its type is T*. As Ferruccio said, int must be replaced with intptr_t to make the program meaningful. 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. XCode 5.1 is change all architecture to 64 bit. It solved my problem too. rev2023.3.3.43278. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 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". If this is the data to a thread procedure, then you quite commonly want to pass by value. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Sign up for a free GitHub account to open an issue and contact its maintainers and the community. 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 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;. x is a local variable and its lifetime ends as soon as control leaves the scope it was defined in. The high-order 9 bits of the number are used to hold a flag value, and the result is converted back into a pointer. How to make compiler not show int to void pointer cast warnings, incompatible pointer types assigning to 'void (*)(void *)' from 'int (int *)'. However even though their types are different, the address is going to be the same. And you can't pass a pointer to a stack based object from the other thread as it may no longer be valid. Share Improve this answer Follow answered May 6, 2018 at 7:24 Rahul rev2023.3.3.43278. whether it was an actual problem is a different matter though. 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. How to get the error message from the error code returned by GetLastError()? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Is it possible to create a concave light? 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. Converting one datatype into another is known as type casting or, type-conversion. 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. Recovering from a blunder I made while emailing a professor. To learn more, see our tips on writing great answers. ", "? Thus as a result it may be less error prone to generate a pointer dynamcially and use that. 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. Narrowing Casting (manually) - converting a larger type to a . If you do this, you have the thread reference a value that (hopefully still) lives in some other thread. 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. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? And then assign it to the double variable. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 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). In C (int)b is called an explicit conversion, i.e. That's not a good idea if the original object (that was cast to void*) was an integer. 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. (i.e. This page has been accessed 1,655,678 times. @DavidHeffernan, sane thread APIs wouldn't send integral data to the thread procedures, they would send pointers. Create an account to follow your favorite communities and start taking part in conversations. 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. ncdu: What's going on with this second size column? Why does Mister Mxyzptlk need to have a weakness in the comics? What is the purpose of non-series Shimano components? What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? The problem is not with casting, but with the target type loosing half of the pointer. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. In the case of Widening Type Casting, the lower data type (having smaller size) is converted into the higher data type (having larger size). And in this context, it is very very very common to see programmers lazily type cast the. Since gcc compiles that you are performing arithmetic between void* and an int (1024). Whats the grammar of "For those whose stories they are"? 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. SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); "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. C / C++ Forums on Bytes. On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. Asking for help, clarification, or responding to other answers. 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 [.]) That's probably going to be true for most platforms you will ever encounter, but it's not a guarantee; it's implementation-dependent. Connect and share knowledge within a single location that is structured and easy to search. BUT converting a pointer to void* and back again is well supported (everywhere). Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Setting a buffer of char* with intermediate casting to int*. How to correctly cast a pointer to int in a 64-bit application? Whats the grammar of "For those whose stories they are"? gatorade recall 2021, how long after top surgery can i get a tattoo, herissmon cyber sleuth,