SCAN_PUT(ATTR, NULL); 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 do academics stay as adjuncts for years rather than move around? You are just making it bigger by tricking the compiler and the ABI. There is absolutely not gurantee that sizeof(int) <= sizeof(void*). Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin?). 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. You think by casting it here that you are avoiding the problem! 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. 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. 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 No sense in writing a few dozen lines of extra code just to get a bunch of numbered threads. How to use Slater Type Orbitals as a basis functions in matrix method correctly? Does ZnSO4 + H2 at high pressure reverses to Zn + H2SO4? Can Martian regolith be easily melted with microwaves? Thus as a result it may be less error prone to generate a pointer dynamcially and use that. If pointers are 64 bits and ints are 32 bits, an int is too small to hold a pointer value. The int data type is the primary integer data type in SQL Server. Such pointers can be stored in 32-bit data types (for instance, int, DWORD). rev2023.3.3.43278. From what I read about casting in the C11 standard, my feeling is, that it is arguable to emit a warning on an explicit conversion. 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. I have looked around and can't seem to find any information on how to do this. What is the point of Thrower's Bandolier? And you can't pass a pointer to a stack based object from the other thread as it may no longer be valid. SCAN_PUT_ATTR(mask, ATTR, smask, FUNC); GitHub. 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. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? 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 the sizes are different then endianess comes into play. [that could be a TODO - not to delay solving the ICE]. 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 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). 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. The difference between the phonemes /p/ and /b/ in Japanese. This will get you a pointer from a 32 bit offset: A function pointer is incompatible to void* (and any other non function pointer). A nit: in your version, the cast to void * is unnecessary. Is it possible to create a concave light? ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' How to correctly cast a pointer to int in a 64-bit application? then converted back to pointer to void, and the result will compare Asking for help, clarification, or responding to other answers. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Actions. You can use any other pointer, or you can use (size_t), which is 64 bits. -1, Uggh. The 32 remaining bits stored inside int are insufficient to reconstruct a pointer to the thread function. 471,961 Members | 900 Online. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? Note the difference between the type casting of a variable and type casting of a pointer. Does Counterspell prevent from any further spells being cast on a given turn? Not the answer you're looking for? How do I set, clear, and toggle a single bit? Thanks for contributing an answer to Stack Overflow! eg. Identify those arcade games from a 1983 Brazilian music video. Update: Today, i download the latest version of cocos2d-x (cocos2d-x 2.2.3). That's not a good idea if the original object (that was cast to void*) was an integer. 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. The point is (probably) that the value passed to the thread is an integer value, not really a 'void *'. to the original pointer: The following type designates an unsigned integer type with the Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? equal to the original pointer: First you are using a define, which is not a variable. Did i have to face to unexpected runtime issues, i guess not, i've found another discussion on this -. Why does flowing off the end of a non-void function without returning a value not produce a compiler error? Surely the solution is to change the type of ids from int to type that is sufficiently large to hold a pointer. Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin? What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. Asking for help, clarification, or responding to other answers. Issues. How do I align things in the following tabular environment? Disconnect between goals and daily tasksIs it me, or the industry? Most answers just try to extract 32 useless bits out of the argument. . Bulk update symbol size units from mm to map units in rule-based symbology. How do I force make/GCC to show me the commands? 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). 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. Converting a void* to an int is non-portable way that may work or may not! How to tell which packages are held back due to phased updates, Identify those arcade games from a 1983 Brazilian music video. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? 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 ) What is the purpose of non-series Shimano components? 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. What you do here is undefined behavior, and undefined behavior of very practical sort. Can anybody explain how to pass an integer to a function which receives (void * ) as a parameter? Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. what does it mean to convert int to void* or vice versa? You cannot just cast the 32-bit variable to a pointer, because that pointer on a 64-bit machine is twice as long. Converts between types using a combination of implicit and user-defined conversions. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. This is not a conversion at all. vegan) just to try it, does this inconvenience the caterers and staff? Please help me compile Chez Scheme. casting from int to void* and back to int. The most general answer is - in no way. 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. If your standard library (even if it is not C99) happens to provide these types - use them. Do new devs get fired if they can't solve a certain bug? The cast back to int * is not, though. This is a fine way to pass integers to new pthreads, if that is what you need. In such condition type conversion (type promotion) takes place to avoid loss of data. warning C4311: 'type cast': pointer truncation from 'void *' to 'long' in ECPG test files. 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. You should perform type conversion based on 64bit build system because the type "int" supports only -32768 ~ 32768. 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; The result is the same as implicit conversion from the enum's underlying type to the destination type. You are right! For example, the main thread could wait for all of the other threads to end before terminating. Why is there a voltage on my HDMI and coaxial cables? Thanks for contributing an answer to Stack Overflow! Share Improve this answer Follow answered May 6, 2018 at 7:24 Rahul Visit Microsoft Q&A to post new questions. Find centralized, trusted content and collaborate around the technologies you use most. return ((void **) returnPtr);} /* Matrix() */. 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. Bulk update symbol size units from mm to map units in rule-based symbology. This forum has migrated to Microsoft Q&A. Once you manage to make this cast, then what?! Narrowing Casting (manually) - converting a larger type to a . I'm new to coding and am trying to implement a simple program on my own, that prompts the user the number of residents in an apt complex, the prompts the user to enter the names and apt numbers of each resident. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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 need to cast the int from the first function so that I can use it as an argument for the second function. Taking the above declarations of A, D, ch of the . ^~~~~~~~~~~~~~~~~~~~ Remembering to delete the pointer after use so that we don't leak. No idea how it amassed 27 upvotes?! @DavidHeffernan I rephrased that sentence a little. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ This is not even remotely "the correct answer". What happens if you typecast as unsigned first? Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? pthread create managing values generated in function (in c), Establishing TCP socket connection between PHP client and C server on Ubuntu. To learn more, see our tips on writing great answers. This will only compile if the destination type is long enough. The problem just occur with Xcode 5.1. 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. If the destination type is bool, this is a boolean conversion (see below). vegan) just to try it, does this inconvenience the caterers and staff? 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 result is implementation-defined and typically yields the numeric address of the byte in memory that the pointer pointers to. The proper way is to cast it to another pointer type. 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 Yesterday, I updated Xcode to the newest version (5.1 (5B130a)) to compatible with iOS 7.1. Then i can continue compiling. Infact I know several systems where that does not hold. Therefore, you need to change it to long long instead of long in windows for 64 bits. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. So you know you can cast it back like this. If you do this, you have the thread reference a value that (hopefully still) lives in some other thread. Based on the design of this function, which modification is right. Whats the grammar of "For those whose stories they are"? It solved my problem too. If not, check the pointer size on your platform, define these typedefs accordingly yourself and use them. "After the incident", I started to be more careful not to trip over things. That could create all kinds of trouble. Apparently the clang version in Xcode 5.1 and above is more strict about potential 32bit vs. 64 bit incompatibilities in source code than older clang versions have been. 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). It is done by the compiler on its own, without any external trigger from the user. The value of float variable is= 37.75. The subreddit for the C programming language, Press J to jump to the feed. B programing language is a language based on basic combined programming or a BCPL, and it is the precursor of the C programming language. Just edited. Thanks for contributing an answer to Stack Overflow! Why is there a voltage on my HDMI and coaxial cables? It was derived from the BCPL, and the name of the b language is possibly from the BCPL contraction. // OK: lvalue denoting the original d object, // UB: the b subobject is not a base class subobject, // 6. array-to-pointer followed by upcast, https://en.cppreference.com/mwiki/index.php?title=cpp/language/static_cast&oldid=147983, when converting a 'pointer to object' to 'pointer to, the conversion from floating-point values, the conversion from bit-fields to rvalue references, the conversion from integral or enumeration values to enumeration, the conversion from integral or enumeration values to, the conversion from a member of base class type to, a standard-layout class object with no data members, a non-standard-layout union object and a non-static data, for base-to-derived pointer conversions and, the conversion to enumeration types with fixed underlying type, a standard-layout class might have a non-pointer-interconvertible, If the underlying type is not fixed, the behavior is undefined if the value of, If the underlying type is fixed, the result is the same as, one is a union object and the other is a non-static data member of that object, or. This is what the second warning is telling you. Can I tell police to wait and call a lawyer when served with a search warrant? Typically, long or unsigned long is . What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? My code is all over the place now but I appreciate you all helping me on my journey to mastery! What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? I don't see how anything bad can happen . The difference between the phonemes /p/ and /b/ in Japanese, Styling contours by colour and by line thickness in QGIS. How do I count the number of sentences in C using ". This is flat out wrong. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. SCAN_PUT(ATTR, NULL); It is purely a compile-time directive which instructs the compiler to treat expression as if it had . privacy statement. It is easier to understand and write than any other assembly language. Difficulties with estimation of epsilon-delta limit proof. You use the address-of operator & to do that. rev2023.3.3.43278. So make sure you understand what you are doing! If your code has the chance to ever be ported to some platform where this doesn't hold, this won't work. Can I tell police to wait and call a lawyer when served with a search warrant? Where does this (supposedly) Gibson quote come from? The calculated expression consists of two operations. this way you won't get any warning. A cast converts an object or value from one type to another. 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. 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). ../lib/odp-util.c:5489:33: note: expanded from macro 'SCAN_PUT_ATTR' If this is the data to a thread procedure, then you quite commonly want to pass by value. The problem was there before, you just are being notified of it. Are there tables of wastage rates for different fruit and veg? Already on GitHub? Connect and share knowledge within a single location that is structured and easy to search. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? 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. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? ^~~~~~~~~~~~~~~~~~~~ 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. 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. As a result of the integer division 3/2 we get the value 1, which is of the int type. If you really need such trickery, then consider one of dedicated types, which are intptr_t and uintptr_t. I would create a structure and pass that as void* to pthread_create. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. How can this new ban on drag possibly be considered constitutional? How can this new ban on drag possibly be considered constitutional? *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 . Find centralized, trusted content and collaborate around the technologies you use most. Maybe you can try this too. He should pass the address of the integer, the thread should get that address, Note: This is only appropriate is you cast the. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? 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. Using indicator constraint with two variables. All float types are to be converted to double. a cast of which the programmer should be aware of what (s)he is doing. Thanks. In both cases, converting the pointer to an integer type that's too small to represent all pointer values is a bug. But I'm nitpicking .. BUT converting a pointer to void* and back again is well supported (everywhere). 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 For integer casts in specific, using into() signals that . This solution is in accordance with INT18-C. 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. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. Recovering from a blunder I made while emailing a professor. 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 You are correct, but cocos actually only uses that address as a unique id. whether it was an actual problem is a different matter though. Connect and share knowledge within a single location that is structured and easy to search. 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 But this code pass the normal variable .. It generally takes place when in an expression more than one data type is present. Making statements based on opinion; back them up with references or personal experience. If any, how can the original function works without errors if we just ignore the warning. Find centralized, trusted content and collaborate around the technologies you use most. What does casting to void* does when passing arguments to variadic functions? So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. But then you need to cast your arguments inside your thread function which is quite unsafe cf. p-util.c.obj "-c" ../lib/odp-util.c If int is no larger than pointer to void then one way to store the value is by simply copying the bytes: int i . What does it mean to convert int to void* or vice versa? 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.
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