vegan) just to try it, does this inconvenience the caterers and staff? Basically its a better version of (void *)i. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. Here is my code: I already tried (void*)M_TABLE_SIZE but then I get an error that I cannot use the * operator. I think the solution 3> should be the correct one. 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 [.]) You think by casting it here that you are avoiding the problem! 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. for (i=0, j=0; jint, bigint, smallint, and tinyint (Transact-SQL) - SQL Server ), Styling contours by colour and by line thickness in QGIS. 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. rev2023.3.3.43278. ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' C99 defines the types "intptr_t" and "uintptr_t" which do . If this is the data to a thread procedure, then you quite commonly want to pass by value. Safe downcast may be done with dynamic_cast. Difficulties with estimation of epsilon-delta limit proof. However the actual code in question contains an explicit c-style cast to int. This is known as implicit type casting or type promotion, compiler automatically converts smaller data type to larger data type. rev2023.3.3.43278. What is the point of Thrower's Bandolier? Only the following conversions can be done with static_cast, except when such conversions would cast away constness or volatility. It is commonly called a pointer to T and its type is T*. error: cast from 'void*' to 'int' loses precision - Stack Overflow static_cast conversion - cppreference.com What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? Making statements based on opinion; back them up with references or personal experience. Java Type Casting (With Examples) - Programiz The preprocessor will replace your code by this: This is unlikely what you are trying to do. static_cast on the other hand should deny your stripping away the const qualifier. It modifies >> Wconversion-real.c, Wconversion-real-integer.c and pr35635.c to be more >> specific > > If the patch passes existing tests, I'd be inclined to leave them > tests alone and add new ones that are specific to what this patch > changes. 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. ", "!"? Making statements based on opinion; back them up with references or personal experience. How to notate a grace note at the start of a bar with lilypond? Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? I usually have all automatic conversion warnings effective when developing in C, and I use explicit casting in order to suppress a specific . 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. Half your pointer will be garbage. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? 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. ^~~~~~~~~~~~~~~~~~~~~ Hence there is no loss in data. Actions. 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. privacy statement. 4. Type Conversions - C in a Nutshell [Book] - O'Reilly Online Learning 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. arrays - I get the error: "cast to smaller integer type 'int' from SCAN_PUT_ATTR(mask, ATTR, smask, FUNC); Pull requests. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 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. How do I count the number of sentences in C using ". I have a function with prototype void* myFcn(void* arg) which is used as the starting point for a pthread. 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]. c - How to cast an integer to void pointer? - Stack Overflow Cerror: cast to 'void *' from smaller integer type 'int' What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? Star 675. The proper way is to cast it to another pointer type. Types - D Programming Language The 32 remaining bits stored inside int are insufficient to reconstruct a pointer to the thread function. Based on the design of this function, which modification is right. SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); } SCAN_END_SINGLE(ATTR) - the incident has nothing to do with me; can I use this this way? this question. I assumed that gcc makes a 65536 out of my define, but I was wrong. Most answers just try to extract 32 useless bits out of the argument. what does it mean to convert int to void* or vice versa? 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. He should pass the address of the integer, the thread should get that address, Note: This is only appropriate is you cast the. GitHub. Please tell me error: cast from 'void*' to 'int' loses precision, How Intuit democratizes AI development across teams through reusability. ", "? What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? [Solved] Error "Cast from pointer to smaller type 'int' | 9to5Answer 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" (. [] 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). I'm trying to create a void* from an int. 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 ) Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, @Dinesh: could you please 1) show us those. 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. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. If you preorder a special airline meal (e.g. Now, what happens when I run it with the thread sanitizer? Please unaccept the answer you have chosen as it is wrong (as the comments below it say) and will lead to bugs. How to correctly cast a pointer to int in a 64-bit application? Converts between types using a combination of implicit and user-defined conversions. But gcc always give me a warning, that i cannot cast an int to a void*. Remembering to delete the pointer after use so that we don't leak. windows meson: cast to smaller integer type 'unsigned long' from 'void Instead of using a long cast, you should cast to size_t. Pd = Pa; Similarly, Pc may be type cast to type int and assigned the value Pa. 1. B language was designed to develop . 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. [mst-vhost:vhost 5/52] drivers/block/virtio_blk.c:539:21: warning Fork 63. static const void* M_OFFSET = (void*)64*1024; Since gcc compiles that you are performing arithmetic between void* and an int ( 1024 ). 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;. The only exception is exotic systems with the SILP64 data model, where the size of int is also 64 bits. If the original pointer value represents an address of a byte in memory that does not satisfy the alignment requirement of the target type, then the resulting pointer value is unspecified. Floating-point conversions It is done by the compiler on its own, without any external trigger from the user. 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. Click to see the query in the CodeQL repository. Connect and share knowledge within a single location that is structured and easy to search. rev2023.3.3.43278. How to correctly type cast (void*)? - social.msdn.microsoft.com To be honest, I think, clang is too restrictive here. 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. Does Counterspell prevent from any further spells being cast on a given turn? long guarantees a pointer size on Linux on any machine. What happens if you typecast as unsigned first? a cast of which the programmer should be aware of what (s)he is doing. 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. Mutually exclusive execution using std::atomic? Connect and share knowledge within a single location that is structured and easy to search. 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". cast to 'void *' from smaller integer type 'int' Converting a void* to an int is non-portable way that may work or may not! What is the purpose of this D-shaped ring at the base of the tongue on my hiking boots? What you do here is undefined behavior, and undefined behavior of very practical sort. How to use Slater Type Orbitals as a basis functions in matrix method correctly? Can I tell police to wait and call a lawyer when served with a search warrant? vegan) just to try it, does this inconvenience the caterers and staff? Bulk update symbol size units from mm to map units in rule-based symbology. Alternatively, if you choose to castthe ptr variableto (size_t) instead, then you don't need to worry about the pointer typeanymore. Have a question about this project? Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? In the case of Widening Type Casting, the lower data type (having smaller size) is converted into the higher data type (having larger size). Once you manage to make this cast, then what?! @LearnCocos2D: so, how can i "overcome" the error without editing any not-my-code or in-library-file lines? If not, check the pointer size on your platform, define these typedefs accordingly yourself and use them. 7.1 New Cast Operations The C++ standard defines new cast operations that provide finer control than previous cast operations. 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. Thanks for contributing an answer to Stack Overflow! Returns a value of type new-type. Find centralized, trusted content and collaborate around the technologies you use most. What is the purpose of non-series Shimano components? /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. I need to cast the int from the first function so that I can use it as an argument for the second function. 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. 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. c - Cast int to void* - Stack Overflow On most platforms pointers and longs are the same size, but ints and pointers often are not the same size on 64bit platforms. @DavidHeffernan I rephrased that sentence a little. Type conversions - cplusplus.com This is not a conversion at all. Usually that means the pointer is allocated with. The difference between the phonemes /p/ and /b/ in Japanese, Styling contours by colour and by line thickness in QGIS. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, "what happen when typcating normal variable to void* or any pointer variable?" Before I update Xcode, my project still can build and run normally with all devices. itch" "-I..\include\windows" "-Iinclude" "-I..\include" "-I..\datapath-windows\include" "-IC:\PTHREADS-BUILT\include" "-Xclang" "-fcolor-diagnostics" "-pipe" Narrowing Casting (manually) - converting a larger type to a . How do I set, clear, and toggle a single bit? unsigned long call_fn = (unsigned long)FUNC; ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] For a fairly recent compiler (that supports C99) you should not store or represent address as plain int value. (int) pthread_self() 64int48intuintptr_t (unsigned int) Using an integer address (like &x) is probably wrong, indeed each modification you will execute on x will affect the pass behaviour. SQL Server does not automatically promote . 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 While working with Threads in C, I'm facing the warning, "warning: cast to pointer from integer of different 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. reinterpret_cast is a type of casting operator used in C++. If the sizes are different then endianess comes into play. 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; ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. I am compiling this program in linux gcc compiler.. Java Type Casting. SCAN_PUT(ATTR, NULL); The calculated expression consists of two operations. 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. It solved my problem too. To learn more, see our tips on writing great answers. 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. Mutually exclusive execution using std::atomic? Don't do that. Casting arguments inside the function is a lot safer. ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] [that could be a TODO - not to delay solving the ICE]. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? Such pointers can be stored in 32-bit data types (for instance, int, DWORD). (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. "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. All character types are to be converted to an integer. If int is no larger than pointer to void then one way to store the value is by simply copying the bytes: int i . Error while setting app icon and launch image in xcode 5.1. This is an old C callback mechanism so you can't change that. @BlueMoon Thanks a lot! Getting Command /bin/sh failed with exit code 65 Error with Xcode 5.1 . This is flat out wrong. You are just making it bigger by tricking the compiler and the ABI. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? Projects. 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; Asking for help, clarification, or responding to other answers. If the value is ever used as pointer again that will prove to be an extremely bad idea. The following program casts a double to an int. The problem is not with casting, but with the target type loosing half of the pointer. 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. ^~~~~~~~~~~~~~~~~~~~ @Artelius: Which, presumably, is exactly what Joshua did: A C++ reinterpret cast will not solve the problem. I'm only guessing here, but I think what you are supposed to do is actually pass the address of the variable to the function. How do I align things in the following tabular environment? Yesterday, I updated Xcode to the newest version (5.1 (5B130a)) to compatible with iOS 7.1. error: comparison between pointer and integer ('int' and 'string' (aka 'char *')), CS50 Caesar program is working but check50 says it isn't. reinterpret_cast conversion - cppreference.com The OP wanted to convert a pointer value to a int value, instead, most the answers, one way or the other, tried to wrongly convert the content of arg points to to a int value. This allows you to reinterpret the void * as an int. There's no proper way to cast this to int in general case. 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. [PATCH] platform/x86: hp-wmi: Fix cast to smaller integer type warning ../lib/odp-util.c:5603:13: note: expanded from macro 'SCAN_PUT' 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. 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 Using Kolmogorov complexity to measure difficulty of problems? 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. 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 Please help me compile Chez Scheme. The main point is: a pointer has a platform dependent size. p-util.c.obj "-c" ../lib/odp-util.c Is it suspicious or odd to stand by the gate of a GA airport watching the planes? For the Nozomi from Shinagawa to Osaka, say on a Saturday afternoon, would tickets/seats typically be available - or would you need to book? On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. If you really need such trickery, then consider one of dedicated types, which are intptr_t and uintptr_t. 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. return ((void **) returnPtr);} /* Matrix() */. In Java, there are two types of casting: Widening Casting (automatically) - converting a smaller type to a larger type size. Find centralized, trusted content and collaborate around the technologies you use most. How create a simple program using threads in C? Why do small African island nations perform better than African continental nations, considering democracy and human development? Why does setupterm terminate the program? Why is this sentence from The Great Gatsby grammatical? Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. The problem just occur with Xcode 5.1. You are correct, but cocos actually only uses that address as a unique id.

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