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), For those who are interested. Why does setupterm terminate the program? Before I update Xcode, my project still can build and run normally with all devices. ^~~~~~~~~~~~~~~~~~~ (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. How to use Slater Type Orbitals as a basis functions in matrix method correctly? How do I force make/GCC to show me the commands? That could create all kinds of trouble. reinterpret_cast is a type of casting operator used in C++. ../lib/odp-util.c:5489:33: note: expanded from macro 'SCAN_PUT_ATTR' } SCAN_END_SINGLE(ATTR) error: cast from pointer to smaller type 'unsigned int' loses information. Does ZnSO4 + H2 at high pressure reverses to Zn + H2SO4? Since gcc compiles that you are performing arithmetic between void* and an int (1024). Since all pointers on 64-bit Windows are 64 bits, you are growing the data size from 32 bits backto 64 bits. 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. You are correct, but cocos actually only uses that address as a unique id. Does a summoned creature play immediately after being summoned by a ready action? You are getting warnings due to casting a void* to a type of a different size. To avoid truncating your pointer, cast it to a type of identical size. ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' Visit Microsoft Q&A to post new questions. Narrowing Casting (manually) - converting a larger type to a . Connect and share knowledge within a single location that is structured and easy to search. 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 [.]) There is absolutely not gurantee that sizeof(int) <= sizeof(void*). In Java, there are two types of casting: Widening Casting (automatically) - converting a smaller type to a larger type size. "I think what you should do is actually pass the address of the variable to the function" Not necessarily. ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' rev2023.3.3.43278. A cast specifies a conversion from one type to another. 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;. Using Kolmogorov complexity to measure difficulty of problems? 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 Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? Usually that means the pointer is allocated with. 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. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Using Kolmogorov complexity to measure difficulty of problems? Surely the solution is to change the type of ids from int to type that is sufficiently large to hold a pointer. eg. @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. 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. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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. You can use any other pointer, or you can use (size_t), which is 64 bits. Implicit Type Conversion is also known as 'automatic type conversion'. Losing bytes like thisis called 'truncation', and that's what the first warning is telling you. 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. This method will not work on 64 bit Big Endian platform, so it unnecessarily breaks portability. Hence there is no loss in data. Using indicator constraint with two variables. 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. } SCAN_END_SINGLE(ATTR) You are getting warnings due to casting a void* to a type of a different size. Yeah, the tutorial is doing it wrong. byte -> short -> char -> int -> long -> float -> double. What is the correct method to cast an int to a void*? Thus as a result it may be less error prone to generate a pointer dynamcially and use that. Therefore it is perfectly valid for the compiler to throw an error for a line like. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. A void pointer can be really useful if the programmer is not sure about the data type of data inputted by the end user. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? To perform a cast, specify the type that you are casting to in parentheses in front of the value or variable to be converted. I'm trying to learn pthreads and thing that keeps bugging me is how do i really pass argument to the function. How Intuit democratizes AI development across teams through reusability. pthread passes the argument as a void*. The text was updated successfully, but these errors were encountered: You signed in with another tab or window. Is it possible to create a concave light? However, you are also casting the result of this operation to (void*). Not the answer you're looking for? ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ To learn more, see our tips on writing great answers. 7.1 New Cast Operations The C++ standard defines new cast operations that provide finer control than previous cast operations. Remarks. If you cast an int pointer int, you might get back a different integer. (void *)i Error: cast to 'void *' from smaller integer type 'int' PS: UBUNTUCLANG3.5 clang -O0 -std=gnu11 -march=native -lm -lpthread pagerank.c -o pagerank c pthreads 4 10.3k 2 21 2015-06-05 @kshegunov said in Number Type Cast: const void * x; int y = int (x); compiles just fine. Thanks for contributing an answer to Stack Overflow! You could use this code, and it would do the same thing as casting ptr to (char*). SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); static const void* M_OFFSET = (void*)64*1024; Since gcc compiles that you are performing arithmetic between void* and an int ( 1024 ). Taking the above declarations of A, D, ch of the . Thanks for pointing that out. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. [that could be a TODO - not to delay solving the ICE]. On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. 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 you call your thread creation function like this, then the void* arriving inside of myFcn has the value of the int you put into it. Please unaccept the answer you have chosen as it is wrong (as the comments below it say) and will lead to bugs. Thanks. For example, if you want to store a 'long' value into a simple integer then you can type cast 'long' to 'int'. 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. unsigned long call_fn = (unsigned long)FUNC; ^~~~~~~~~~~~~~~~~~~~~ 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. Such a downcast makes no runtime checks to ensure that the object's runtime type is actually D, and may only be used safely if this precondition is guaranteed by other means, such as when implementing static polymorphism. Identify those arcade games from a 1983 Brazilian music video. Can anybody explain how to pass an integer to a function which receives (void * ) as a parameter? XCode 5.1 is change all architecture to 64 bit. @Shahbaz you could but I will not suggest to a C newbie to use globals. equal to the original pointer: First you are using a define, which is not a variable. All float types are to be converted to double. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. If you really need such trickery, then consider one of dedicated types, which are intptr_t and uintptr_t. This is flat out wrong. 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. 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). Why is there a voltage on my HDMI and coaxial cables? An object pointer (including void*) or function pointer can be converted to an integer type using reinterpret_cast. (void *)i Error: cast to 'void *' from smaller integer type 'int'. Why is there a voltage on my HDMI and coaxial cables? 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. Star 675. vegan) just to try it, does this inconvenience the caterers and staff? Just re-enforcing the old behavior of Xcode 5.0 and earlier versions, that already cut away parts of the address by casting it to int, won't introduce any new bugs and avoids the need to learn and understand lots of implementation-internal cocos code. ^~~~~~~~~~~~~~~~~~~~ This is memory reinterpretation - a completely unacceptable way to do what the OP is trying to do. 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 subscribe to this RSS feed, copy and paste this URL into your RSS reader. This will only compile if the destination type is long enough. How do I align things in the following tabular environment? For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. 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. Returns a value of type new-type. Did i have to face to unexpected runtime issues, i guess not, i've found another discussion on this -. 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). and how to print the thread id of 2d array argument? The subreddit for the C programming language, Press J to jump to the feed. Put your define inside a bracket: #define M_TABLE_SIZE (64*1024) Now, you can do: static const void* M_OFFSET = (void*) M_TABLE_SIZE; without a problem. ncdu: What's going on with this second size column? Connect and share knowledge within a single location that is structured and easy to search. And then assign it to the double variable. My code is all over the place now but I appreciate you all helping me on my journey to mastery! Notifications. It is easier to understand and write than any other assembly language. SCAN_PUT_ATTR(mask, ATTR, smask, FUNC); Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. To learn more, see our tips on writing great answers. 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. ../lib/odp-util.c:5603:13: note: expanded from macro 'SCAN_PUT' What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? p-util.c.obj "-c" ../lib/odp-util.c 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". However even though their types are different, the address is going to be the same. Then i can continue compiling. C++ how to get the address stored in a void pointer? this way I convert an int to a void* which is much better than converting a void* to an int. . Please tell me error: cast from 'void*' to 'int' loses precision, How Intuit democratizes AI development across teams through reusability. I don't see how anything bad can happen . Terrible solution. SCAN_PUT_ATTR(key, ATTR, skey, FUNC); By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 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. 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. Here, the Java first converts the int type data into the double type. void* -> integer -> void* rather than integer -> void* -> integer. Is a PhD visitor considered as a visiting scholar. If any, how can the original function works without errors if we just ignore the warning. Note the difference between the type casting of a variable and type casting of a pointer. How to use Slater Type Orbitals as a basis functions in matrix method correctly? But assuming that it is, as long as the caller and the callee agree, you can do that sort of thing. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. The main point is: a pointer has a platform dependent size. The proper way is to cast it to another pointer type. Issues. actually no, as int my be a smaller type than a pointer ;-) But, of course with int64_t it works fine. - the incident has nothing to do with me; can I use this this way? If the value in a pointer is cast to a different type and it does not have the correct alignment for the new type, the behavior is undefined. Can I tell police to wait and call a lawyer when served with a search warrant? How to get the error message from the error code returned by GetLastError()? I have a function with prototype void* myFcn(void* arg) which is used as the starting point for a pthread. Converting a pointer to an integer whose result cannot represented in the integer type is undefined behavior is C and prohibited in C++. I need to cast the int from the first function so that I can use it as an argument for the second function. 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. However, I believe that even if the define was for the "65536", it would not be what @kaetzacoatl wanted. "-I.." "-Iinclude\openflow" "-I..\include\openflow" "-Iinclude\openvswitch" "-I..\include\openvsw Please help me compile Chez Scheme. Put your define inside a bracket: without a problem. Making statements based on opinion; back them up with references or personal experience. Implementation-dependent. Thanks for contributing an answer to Stack Overflow! The 32 remaining bits stored inside int are insufficient to reconstruct a pointer to the thread function. *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 . Are there tables of wastage rates for different fruit and veg? But this code pass the normal variable .. Asking for help, clarification, or responding to other answers. Unless you have a valid address at that value, you are going to invoke undefined behaviour when try to use that pointer. Getting Command /bin/sh failed with exit code 65 Error with Xcode 5.1 . 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. @Martin York: No, it doesn't depend on endiannness. In this case, casting the pointer back to an integer is meaningless, because . then converted back to pointer to void, and the result will compare Next, when doing pointer arithmetic, the addition operation will use the pointer's type to determine how many bytes to add to it when incrementing it. This solution is in accordance with INT18-C. What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Xcode 5 and iOS 7: Architecture and Valid architectures, xcode build error: Semantic issue cast from pointer to smaller type 'int' loses information, Issues in handling touches on subviews(uiviews) in UIScrollView, Architecture linking error after Xcode 5.1 upgrade, iOS 7.1 gives error after updating to Xcode 5.1, Linker error in Xcode 5.1 with cocos2d-x 3 beta 2. ^~~~~~~~~~~~~~~~~~~~ to the original pointer: The following type designates an unsigned integer type with the that any valid pointer to void can be converted to this type, then Use #include to define it. 10) A prvalue of type pointer to void (possibly cv-qualified) can be converted to pointer to any object type. If int is no larger than pointer to void then one way to store the value is by simply copying the bytes: int i . Any help with this is appreciated. 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. Sign up for a free GitHub account to open an issue and contact its maintainers and the community. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Well it does this because you are converting a 64 bits pointer to an 32 bits integer so you loose information. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. In such condition type conversion (type promotion) takes place to avoid loss of data. He should pass the address of the integer, the thread should get that address, Note: This is only appropriate is you cast the. Here is my code: I already tried (void*)M_TABLE_SIZE but then I get an error that I cannot use the * operator. Now, what happens when I run it with the thread sanitizer? 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. And you can't pass a pointer to a stack based object from the other thread as it may no longer be valid. 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. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. This page has been accessed 1,655,678 times. Why do small African island nations perform better than African continental nations, considering democracy and human development? In the first example, the variable c1 of the char type is converted to a temporary variable of the int type, because the second operand in the division operation, the constant 2, is of the higher type int. What does it mean to convert int to void* or vice versa? Converts between types using a combination of implicit and user-defined conversions. Here is some piece of code where that error occur: /cocos2d-x-2.2.2/cocos2dx/platform/ios/EAGLView.mm:408:18: Cast from pointer to smaller type 'int' loses information. I wish that you write those answer first than the explanation. C/C++ , Cerror: cast to 'void *' from smaller integer type 'int'. Not the answer you're looking for? . 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. C99 defines the types "intptr_t" and "uintptr_t" which do . Thanks Jonathan, I was thinking about my answer in another thread: AraK is correct, passing integers a pointers are not necessarily interchangeable. 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 ) reinterpret_cast<void *>(42)). How create a simple program using threads in C? LLNL's tutorial is bad and they should feel bad. Find centralized, trusted content and collaborate around the technologies you use most. Replacing broken pins/legs on a DIP IC package, AC Op-amp integrator with DC Gain Control in LTspice. 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 Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Setting a buffer of char* with intermediate casting to int*. 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). (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. 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. LLNL's tutorial is bad and they should feel bad. So make sure you understand what you are doing! 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; This is why you got Error 1 C2036, from your post. Is pthread_join a must when using pthread in linux? -1, Uggh. 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 I understood, but that would introduce dynamic memory and ugly lifetime issues (an object allocated by one thread must be freed by some other) - all just to pass an. For a fairly recent compiler (that supports C99) you should not store or represent address as plain int value. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. what does it mean to convert int to void* or vice versa? How to convert a factor to integer\numeric without loss of information? Yesterday, I updated Xcode to the newest version (5.1 (5B130a)) to compatible with iOS 7.1. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. The reinterpret_cast makes the int the size of a pointer and the warning will stop. You are just making it bigger by tricking the compiler and the ABI. I usually have all automatic conversion warnings effective when developing in C, and I use explicit casting in order to suppress a specific . By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. this way you won't get any warning. Your first example is risky because you have to be very careful about the object lifetimes. Bulk update symbol size units from mm to map units in rule-based symbology. Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin? Type casting is when you assign a value of one primitive data type to another type. Where does this (supposedly) Gibson quote come from? If your standard library (even if it is not C99) happens to provide these types - use them. @Artelius: Which, presumably, is exactly what Joshua did: A C++ reinterpret cast will not solve the problem. This is what the second warning is telling you. To learn more, see our tips on writing great answers. Disconnect between goals and daily tasksIs it me, or the industry? Making statements based on opinion; back them up with references or personal experience. 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 While working with Threads in C, I'm facing the warning, "warning: cast to pointer from integer of different size". We have to pass address of the variable to the function because in function definition argument is pointer variable. This answer is incorrect for the reasons that have already been mentioned in the comment of, Error "Cast from pointer to smaller type 'int' loses information" in EAGLView.mm when update Xcode to 5.1 (5B130a), http://en.wikipedia.org/wiki/64-bit_computing#64-bit_data_models, http://stackoverflow.com/questions/18913906/xcode-5-and-ios-7-architecture-and-valid-architectures, How Intuit democratizes AI development across teams through reusability. Why does flowing off the end of a non-void function without returning a value not produce a compiler error? Casting an open pointer to other pointer types and casting other pointer types to an open pointer does not result in a compile time error. What you do here is undefined behavior, and undefined behavior of very practical sort. So,solution #3 works just fine. I agree passing a dynamically allocated pointer is fine (and I think the best way).