Why does Mister Mxyzptlk need to have a weakness in the comics? "After the incident", I started to be more careful not to trip over things. If your standard library (even if it is not C99) happens to provide these types - use them. Example: int x=7, y=5; float z; z=x/y; /*Here the value of z is 1*/. I guess the other important fact is that the cast operator has higher precedence that the multiplication operator. And, most of these will not even work on gcc4. If you convert (void*) to (long) no precision is lost, then by assigning the (long) to an (int), it properly truncates the number to fit. If pointers are 64 bits and ints are 32 bits, an int is too small to hold a pointer value. 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. Error while setting app icon and launch image in xcode 5.1. A nit: in your version, the cast to void * is unnecessary. : iPhone Retina 4-inch 64-bit) is selected. 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; "-I.." "-Iinclude\openflow" "-I..\include\openflow" "-Iinclude\openvswitch" "-I..\include\openvsw Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Setting a buffer of char* with intermediate casting to int*. If the sizes are different then endianess comes into play. How do I align things in the following tabular environment? Remarks. @Martin York: No, it doesn't depend on endiannness. You can convert the values from one type to another explicitly using the cast operator as follows (type_name) expression . What happens if you typecast as unsigned first? . AC Op-amp integrator with DC Gain Control in LTspice. STR34-C. Do new devs get fired if they can't solve a certain bug? Type casting is when you assign a value of one primitive data type to another type. And in the function you get the value of the pointer by using the dereference operator *: Please read why glib provide macros for this kind of conversions, there's no need to repeat the text here. 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. 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 SCAN_PUT_ATTR(key, ATTR, skey, FUNC); LLNL's tutorial is bad and they should feel bad. ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] The dynamic_cast<>operator provides a way to check the actual type of a pointer to a polymorphic class. rev2023.3.3.43278. What you do here is undefined behavior, and undefined behavior of very practical sort. 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. Update: Today, i download the latest version of cocos2d-x (cocos2d-x 2.2.3). I am an entry level C programmer. Find centralized, trusted content and collaborate around the technologies you use most. ../lib/odp-util.c:5603:13: note: expanded from macro 'SCAN_PUT' You could use this code, and it would do the same thing as casting ptr to (char*). @DavidHeffernan, sane thread APIs wouldn't send integral data to the thread procedures, they would send pointers. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Please unaccept the answer you have chosen as it is wrong (as the comments below it say) and will lead to bugs. ", "!"? Find centralized, trusted content and collaborate around the technologies you use most. Press question mark to learn the rest of the keyboard shortcuts. To perform a cast, specify the type that you are casting to in parentheses in front of the value or variable to be converted. Why does setupterm terminate the program? ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - the incident has nothing to do with me; can I use this this way? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. this way you won't get any warning. Why does flowing off the end of a non-void function without returning a value not produce a compiler error? And you can't pass a pointer to a stack based object from the other thread as it may no longer be valid. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 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. Where does this (supposedly) Gibson quote come from? This is memory reinterpretation - a completely unacceptable way to do what the OP is trying to do. casting from int to void* and back to int. The following program casts a double to an int. It solved my problem too. You are just making it bigger by tricking the compiler and the ABI. In simple example code like this it's very easy to convince yourself that there's no problem, but in more elaborate real-world scenarios it's very easy to make this mistake inadvertently. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. To learn more, see our tips on writing great answers. And when assigning to a void pointer, all type information is lost. If you preorder a special airline meal (e.g. Does Counterspell prevent from any further spells being cast on a given turn? Why do small African island nations perform better than African continental nations, considering democracy and human development? 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" (. I agree passing a dynamically allocated pointer is fine (and I think the best way). lexborisov Modest Public. There's no proper way to cast this to int in general case. 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. ), Styling contours by colour and by line thickness in QGIS. 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)). An open (void) pointer can hold a pointer of any type. It is done by the compiler on its own, without any external trigger from the user. Projects. There is no "correct" way to store a 64-bit pointer in an 32-bit integer. You can only do this if you use a synchronization primitive to ensure that there is no race condition. I need to cast the int from the first function so that I can use it as an argument for the second function. static const void* M_OFFSET = (void*)64*1024; Since gcc compiles that you are performing arithmetic between void* and an int ( 1024 ). If your standard library (even if it is not C99) happens to provide these types - use them. } SCAN_END_SINGLE(ATTR) A cast specifies a conversion from one type to another. @kshegunov said in Number Type Cast: const void * x; int y = int (x); compiles just fine. to the original pointer: The following type designates an unsigned integer type with the 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.. To be honest, I think, clang is too restrictive here. returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size);
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. Already on GitHub? My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? Using indicator constraint with two variables. 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. static_cast on the other hand should deny your stripping away the const qualifier. actually no, as int my be a smaller type than a pointer ;-) But, of course with int64_t it works fine. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? Any help with this is appreciated. reinterpret_cast<void *>(42)). Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Does Counterspell prevent from any further spells being cast on a given turn? Thanks. Is it possible to create a concave light? Unless you have a valid address at that value, you are going to invoke undefined behaviour when try to use that pointer. You are getting warnings due to casting a void* to a type of a different size. Connect and share knowledge within a single location that is structured and easy to search. This returns the first 32 bits of the pointer which may be the top or the bottom depending on big versus little endian, as comment #2 said. You may declare a const int variable and cast its reference to the void*. For example, the main thread could wait for all of the other threads to end before terminating. Issues. For integer casts in specific, using into() signals that . Now, what happens when I run it with the thread sanitizer? rev2023.3.3.43278. 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 For the Nozomi from Shinagawa to Osaka, say on a Saturday afternoon, would tickets/seats typically be available - or would you need to book? What is the purpose of non-series Shimano components? LLNL's tutorial is bad and they should feel bad. From the question I presume the OP does. Before I update Xcode, my project still can build and run normally with all devices. 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. (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. Is a PhD visitor considered as a visiting scholar. ../lib/odp-util.c:5489:33: note: expanded from macro 'SCAN_PUT_ATTR' For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. How to correctly cast a pointer to int in a 64-bit application? vegan) just to try it, does this inconvenience the caterers and staff? Whats the grammar of "For those whose stories they are"? When is casting void pointer needed in C? For a fairly recent compiler (that supports C99) you should not store or represent address as plain int value. As with all cast expressions, the result is: Two objects a and b are pointer-interconvertible if: static_cast may also be used to disambiguate function overloads by performing a function-to-pointer conversion to specific type, as in. Connect and share knowledge within a single location that is structured and easy to search. ^~~~~~~~~~~~~~~~~~~~~ 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. Implementing From will result in the Into implementation but not vice-versa. @DietrichEpp can you explain what is race condition with using. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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. Connect and share knowledge within a single location that is structured and easy to search. itch" "-I..\include\windows" "-Iinclude" "-I..\include" "-I..\datapath-windows\include" "-IC:\PTHREADS-BUILT\include" "-Xclang" "-fcolor-diagnostics" "-pipe" By clicking Sign up for GitHub, you agree to our terms of service and Based on the design of this function, which modification is right. The preprocessor will replace your code by this: This is unlikely what you are trying to do. Does melting sea ices rises global sea level? this question. Even though what you say regarding the lifetime of the object is true, integral types are too limited for a generic API. 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 [.]) If you write ((char*)ptr + 1), it will advance the pointer 1 byte, because a "char" is 1 byte. 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; 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). *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 . How to tell which packages are held back due to phased updates, Identify those arcade games from a 1983 Brazilian music video. Acidity of alcohols and basicity of amines. However even though their types are different, the address is going to be the same. ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' And in this context, it is very very very common to see programmers lazily type cast the. Share Improve this answer Follow answered May 6, 2018 at 7:24 Rahul For example, if you want to store a 'long' value into a simple integer then you can type cast 'long' to 'int'. You should perform type conversion based on 64bit build system because the type "int" supports only -32768 ~ 32768. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? As was pointed out by Martin, this presumes that sizeof(void*)>=sizeof(int). On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. @BlueMoon Thanks a lot! Maybe you can try this too. (i.e. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? eg. How Intuit democratizes AI development across teams through reusability. Getting Command /bin/sh failed with exit code 65 Error with Xcode 5.1 . This forum has migrated to Microsoft Q&A. The problem was there before, you just are being notified of it. rev2023.3.3.43278. Note:You might receive a runtime exception if the pointer contains a value unsuitable for the context. How to make compiler not show int to void pointer cast warnings, incompatible pointer types assigning to 'void (*)(void *)' from 'int (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: I am using size_t here, because it is always having the same size as a pointer, no matter the platform. and how to print the thread id of 2d array argument? 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. This will get you a pointer from a 32 bit offset: A function pointer is incompatible to void* (and any other non function pointer). Sign in for (i=0, j=0; j should be the correct one. Typically, long or unsigned long is . Anw, the project still build and run normally when i use Xcode 5.0 with iOS 7.0. What is the purpose of non-series Shimano components? B programing language is a language based on basic combined programming or a BCPL, and it is the precursor of the C programming language. Thus as a result it may be less error prone to generate a pointer dynamcially and use that. ", "? What is the point of Thrower's Bandolier? 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
Why is there a voltage on my HDMI and coaxial cables? What does it mean to convert int to void* or vice versa? error: cast from pointer to smaller type 'unsigned int' loses information. The value of float variable is= 37.75. Connect and share knowledge within a single location that is structured and easy to search. Well it does this because you are converting a 64 bits pointer to an 32 bits integer so you loose information. converted back to pointer to void, and the result will compare equal equal to the original pointer: First you are using a define, which is not a variable. pthread passes the argument as a void*. The result is implementation-defined and typically yields the numeric address of the byte in memory that the pointer pointers to. Find centralized, trusted content and collaborate around the technologies you use most. To avoid truncating your pointer, cast it to a type of identical size. Why do academics stay as adjuncts for years rather than move around? If you do this, you have the thread reference a value that (hopefully still) lives in some other thread. this way you won't get any warning. 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. 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). Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? 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. 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 ) to your account, [87/252] Compiling C object lib/libopenvswitch.a.p/odp-util.c.obj } SCAN_END_SINGLE(ATTR) Pull requests. (void *)i Error: cast to 'void *' from smaller integer type 'int'. Converting a void* to an int is non-portable way that may work or may not! 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. then converted back to pointer to void, and the result will compare If not, check the pointer size on your platform, define these typedefs accordingly yourself and use them. Converts between types using a combination of implicit and user-defined conversions. If the function had the correct signature you would not need to cast it explicitly. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? In C (int)b is called an explicit conversion, i.e. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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. use $(ARCHS_STANDARD_32_BIT) at Architecture instead of $(ARCHS_STANDARD). rev2023.3.3.43278. Are there tables of wastage rates for different fruit and veg? Please help me compile Chez Scheme. -1, Uggh. 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. Yeah, the tutorial is doing it wrong. 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. What is the difference between const int*, const int * const, and int const *? So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. 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. Identify those arcade games from a 1983 Brazilian music video. The correct answer is, if one does not mind losing data precision. The cast back to int * is not, though. I usually have all automatic conversion warnings effective when developing in C, and I use explicit casting in order to suppress a specific . This page has been accessed 1,655,678 times. 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. Otherwise, if the original pointer value points to an object a, and there is an object b of the . Implicit Type Conversion is also known as 'automatic type conversion'. 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. 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. 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. I'm unfamiliar with XCode, but the solution should be something like follows: Most of the "solutions" above can lose part of the pointer address when casting to a smaller type. So you know you can cast it back like this. All character types are to be converted to an integer. 1. Is it possible to create a concave light? I cannot reverse my upvote of user384706's answer, but it's wrong. Alternatively, if you choose to castthe ptr variableto (size_t) instead, then you don't need to worry about the pointer typeanymore. You can use any other pointer, or you can use (size_t), which is 64 bits. You can fix this error by replacing this line of code. 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. The following behavior-changing defect reports were applied retroactively to previously published C++ standards. But I'm nitpicking .. Whats the grammar of "For those whose stories they are"? windows meson: cast to smaller integer type 'unsigned long' from 'void *'. @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. A cast converts an object or value from one type to another. What does casting to void* does when passing arguments to variadic functions? 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. That could create all kinds of trouble. You need to pass an actual pointer. 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.