If the sizes are different then endianess comes into play. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. But I don't want to edit code in "EAGLView.mm" because it's a "library file". 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. Find centralized, trusted content and collaborate around the technologies you use most. "clang" "-Ilib\libopenvswitch.a.p" "-Ilib" "-I..\lib" "-I." But, sure, in that specific case you can pass a local variable address, type casting integer to void* [duplicate]. How to notate a grace note at the start of a bar with lilypond? B language was designed to develop . Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. 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. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 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. Please tell me error: cast from 'void*' to 'int' loses precision, 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. Connect and share knowledge within a single location that is structured and easy to search. for (i=0, j=0; j to define it. rev2023.3.3.43278. pthread create managing values generated in function (in c), Establishing TCP socket connection between PHP client and C server on Ubuntu. I wish that you write those answer first than the explanation. converted back to pointer to void, and the result will compare equal Thanks for contributing an answer to Stack Overflow! then converted back to pointer to void, and the result will compare I usually have all automatic conversion warnings effective when developing in C, and I use explicit casting in order to suppress a specific . It is commonly called a pointer to T and its type is T*. Why do small African island nations perform better than African continental nations, considering democracy and human development? If int is no larger than pointer to void then one way to store the value is by simply copying the bytes: int i . /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. 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. Casting a pointer to void* and back is valid use of reinterpret_cast<>. Error while setting app icon and launch image in xcode 5.1. That's not a good idea if the original object (that was cast to void*) was an integer. rev2023.3.3.43278. 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" (. Disconnect between goals and daily tasksIs it me, or the industry? : iPhone Retina 4-inch 64-bit) is selected. Find centralized, trusted content and collaborate around the technologies you use most. 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. And when assigning to a void pointer, all type information is lost. Bulk update symbol size units from mm to map units in rule-based symbology. Hence there is no loss in data. What happens if you typecast as unsigned first? vegan) just to try it, does this inconvenience the caterers and staff? If any, how can the original function works without errors if we just ignore the warning. But this code pass the normal variable .. The reinterpret_cast makes the int the size of a pointer and the warning will stop. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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. Sign up for a free GitHub account to open an issue and contact its maintainers and the community. BUT converting a pointer to void* and back again is well supported (everywhere). A cast converts an object or value from one type to another. @DietrichEpp can you explain what is race condition with using. The problem just occur with Xcode 5.1. vegan) just to try it, does this inconvenience the caterers and staff? What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? 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. Cast characters to unsigned char before converting to larger integer sizes Created by Robert Seacord, last modified by Jill Britton on Oct 03, 2022 Signed character data must be converted to unsigned char before being assigned or converted to a larger signed type. Using an integer address (like &x) is probably wrong, indeed each modification you will execute on x will affect the pass behaviour. You may declare a const int variable and cast its reference to the void*. 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. 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 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. this way you won't get any warning. You can fix this error by replacing this line of code. 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 Mutually exclusive execution using std::atomic? Implementing From will result in the Into implementation but not vice-versa. 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. *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 . While working with Threads in C, I'm facing the warning, "warning: cast to pointer from integer of different size". If you are going to pass the address you typically need to exert some more control over the lifetime of the object. Why is there a voltage on my HDMI and coaxial cables? windows meson: cast to smaller integer type 'unsigned long' from 'void *'. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? How to correctly cast a pointer to int in a 64-bit application? Note:You might receive a runtime exception if the pointer contains a value unsuitable for the context. You are correct, but cocos actually only uses that address as a unique id. rev2023.3.3.43278. It's an int type guaranteed to be big enough to contain a pointer. Asking for help, clarification, or responding to other answers. Making statements based on opinion; back them up with references or personal experience. So make sure you understand what you are doing! What is the point of Thrower's Bandolier? It is done by the compiler on its own, without any external trigger from the user. 7.1 New Cast Operations The C++ standard defines new cast operations that provide finer control than previous cast operations. Getting Command /bin/sh failed with exit code 65 Error with Xcode 5.1 . 1. Is it possible to create a concave light? Why is there a voltage on my HDMI and coaxial cables? Can Martian regolith be easily melted with microwaves? 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. I don't see how anything bad can happen . Note the difference between the type casting of a variable and type casting of a pointer. A nit: in your version, the cast to void * is unnecessary. You cannot just cast the 32-bit variable to a pointer, because that pointer on a 64-bit machine is twice as long. 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.. @BlueMoon Thanks a lot! There's no proper way to cast this to int in general case. All character types are to be converted to an integer. We have to pass address of the variable to the function because in function definition argument is pointer variable. to the original pointer: The following type designates an unsigned integer type with the By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. For integer casts in specific, using into() signals that . 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. Connect and share knowledge within a single location that is structured and easy to search. STR34-C. Thank you all for your feedback. what does it mean to convert int to void* or vice versa? To learn more, see our tips on writing great answers. ), Styling contours by colour and by line thickness in QGIS. This is what the second warning is telling you. - the incident has nothing to do with me; can I use this this way? ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' 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. @DavidHeffernan I rephrased that sentence a little. So,solution #3 works just fine. Unless you have a valid address at that value, you are going to invoke undefined behaviour when try to use that pointer. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. what does it mean to convert int to void* or vice versa? As was pointed out by Martin, this presumes that sizeof(void*)>=sizeof(int). ^~~~~~~~~~~~~~~~~~~~~ How do I check if a string represents a number (float or int)? The main point is: a pointer has a platform dependent size. It's always a good practice to put your #define's in brackets to avoid such surprise. Asking for help, clarification, or responding to other answers. If the destination type is bool, this is a boolean conversion (see below). long guarantees a pointer size on Linux on any machine. 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. What is the point of Thrower's Bandolier? Converts between types using a combination of implicit and user-defined conversions. C/C++ , Cerror: cast to 'void *' from smaller integer type 'int'. Using Kolmogorov complexity to measure difficulty of problems? However the actual code in question contains an explicit c-style cast to int. 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. How do I force make/GCC to show me the commands? You need to pass an actual pointer. All float types are to be converted to double. The difference between a and &a is the type. You are getting warnings due to casting a void* to a type of a different size. How to make compiler not show int to void pointer cast warnings, incompatible pointer types assigning to 'void (*)(void *)' from 'int (int *)'. Now, what happens when I run it with the thread sanitizer? The difference between the phonemes /p/ and /b/ in Japanese, Styling contours by colour and by line thickness in QGIS. Connect and share knowledge within a single location that is structured and easy to search. What is the difference between const int*, const int * const, and int const *? Does Counterspell prevent from any further spells being cast on a given turn? Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. This page has been accessed 1,655,678 times. (void *)i Error: cast to 'void *' from smaller integer type 'int'. ../lib/odp-util.c:5603:13: note: expanded from macro 'SCAN_PUT' What I am trying to emphasis that conversion from int to pointer and back again can be frough with problems as you move from platform to platform. When is casting void pointer needed in C? That could create all kinds of trouble. Thanks. 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. 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. Thanks for contributing an answer to Stack Overflow! Why is this sentence from The Great Gatsby grammatical? Where does this (supposedly) Gibson quote come from? casting from int to void* and back to int. But then you need to cast your arguments inside your thread function which is quite unsafe cf. How do I align things in the following tabular environment? You are getting warnings due to casting a void* to a type of a different size. How create a simple program using threads in C? ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' How can this new ban on drag possibly be considered constitutional? 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 difference between the phonemes /p/ and /b/ in Japanese, Styling contours by colour and by line thickness in QGIS, AC Op-amp integrator with DC Gain Control in LTspice, Identify those arcade games from a 1983 Brazilian music video. How to use Slater Type Orbitals as a basis functions in matrix method correctly? Making statements based on opinion; back them up with references or personal experience. 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. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. } SCAN_END_SINGLE(ATTR) Bulk update symbol size units from mm to map units in rule-based symbology. Most answers just try to extract 32 useless bits out of the argument. void* -> integer -> void* rather than integer -> void* -> integer. linux c-pthreads: problem with local variables. Mutually exclusive execution using std::atomic? Fork 63. Here, the Java first converts the int type data into the double type. Passing arguments to pthread_create - invalid conversion from void(*)() to void(*)(void*). Converting a void* to an int is non-portable way that may work or may not! In such condition type conversion (type promotion) takes place to avoid loss of data. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Again, all of the answers above missed the point badly. Can I tell police to wait and call a lawyer when served with a search warrant? On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. In Java, there are two types of casting: Widening Casting (automatically) - converting a smaller type to a larger type size. Thanks for contributing an answer to Stack Overflow! Netdev Archive on lore.kernel.org help / color / mirror / Atom feed * [mst-vhost:vhost 5/52] drivers/block/virtio_blk.c:539:21: warning: assignment to 'void *' from . ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. You should perform type conversion based on 64bit build system because the type "int" supports only -32768 ~ 32768. 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". 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. An object pointer (including void*) or function pointer can be converted to an integer type using reinterpret_cast. You can use a 64 bits integer instead howerver I usually use a function with the right prototype and I cast the function type : Just edited. Please unaccept the answer you have chosen as it is wrong (as the comments below it say) and will lead to bugs. Why do academics stay as adjuncts for years rather than move around? If you really need such trickery, then consider one of dedicated types, which are intptr_t and uintptr_t. This is an old C callback mechanism so you can't change that. SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); "-D_FILE_OFFSET_BITS=64" "-Wall" "-Winvalid-pch" "-g" "-Wthread-safety" "-Wno-microsoft-enum-forward-reference" "-Wno-unused-function" "-Wno-sometimes-unini As a result of the integer division 3/2 we get the value 1, which is of the int type. 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. Such pointers can be stored in 32-bit data types (for instance, int, DWORD). 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. Using indicator constraint with two variables. @kshegunov said in Number Type Cast: const void * x; int y = int (x); compiles just fine. Whats the grammar of "For those whose stories they are"? I guess the other important fact is that the cast operator has higher precedence that the multiplication operator. lexborisov Modest Public. reinterpret_cast is a type of casting operator used in C++. 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. A nit: in your version, the cast to void * is unnecessary. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? Implementation-dependent. Wrong. But the problem has still happened. Issues. The most general answer is - in no way. I have a two functions, one that returns an int, and one that takes a const void* as an argument. warning C4311: 'type cast': pointer truncation from 'void *' to 'long' in ECPG test files. In the case of Widening Type Casting, the lower data type (having smaller size) is converted into the higher data type (having larger size). Find centralized, trusted content and collaborate around the technologies you use most. How do I count the number of sentences in C using ". Use returnPtr[j] = (void *) ((long)ptr + i); ). Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Any help with this is appreciated. (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 ../lib/odp-util.c:5601:9: note: expanded from macro 'SCAN_PUT' @Shahbaz you could but I will not suggest to a C newbie to use globals. What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. Pd = Pa; Similarly, Pc may be type cast to type int and assigned the value Pa. 1. Safe downcast may be done with dynamic_cast. As Ferruccio said, int must be replaced with intptr_t to make the program meaningful. 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. to your account, [87/252] Compiling C object lib/libopenvswitch.a.p/odp-util.c.obj Put your define inside a bracket: without a problem. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. I'm trying to create a void* from an int. byte -> short -> char -> int -> long -> float -> double. ../lib/odp-util.c:5489:33: note: expanded from macro 'SCAN_PUT_ATTR' Basically its a better version of (void *)i. This will only compile if the destination type is long enough. To be honest, I think, clang is too restrictive here. Well occasionally send you account related emails. It is purely a compile-time directive which instructs the compiler to treat expression as if it had . ^~~~~~~~~~~~~~~~~~~~~ Yeah, the tutorial is doing it wrong. In this case, casting the pointer back to an integer is meaningless, because . */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j; Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin?). error: comparison between pointer and integer ('int' and 'string' (aka 'char *')), CS50 Caesar program is working but check50 says it isn't. 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. Find centralized, trusted content and collaborate around the technologies you use most. The 32 remaining bits stored inside int are insufficient to reconstruct a pointer to the thread function. // 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. What is the purpose of non-series Shimano components? 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). 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. Thanks Jonathan, I was thinking about my answer in another thread: AraK is correct, passing integers a pointers are not necessarily interchangeable. 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.