Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. FAILED: lib/libopenvswitch.a.p/odp-util.c.obj However even though their types are different, the address is going to be the same. How Intuit democratizes AI development across teams through reusability. It's always a good practice to put your #define's in brackets to avoid such surprise. Issues. Thanks for contributing an answer to Stack Overflow! I'm trying to learn pthreads and thing that keeps bugging me is how do i really pass argument to the function. Typically, long or unsigned long is . Connect and share knowledge within a single location that is structured and easy to search. this way you won't get any warning. This is why you got Error 1 C2036, from your post. Have a question about this project? The problem was there before, you just are being notified of it. Mutually exclusive execution using std::atomic? byte -> short -> char -> int -> long -> float -> double. The int data type is the primary integer data type in SQL Server. ", "? How do I align things in the following tabular environment? For integer casts in specific, using into() signals that . Bulk update symbol size units from mm to map units in rule-based symbology. Taking the above declarations of A, D, ch of the . If the sizes are different then endianess comes into play. AC Op-amp integrator with DC Gain Control in LTspice. 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.. How to use Slater Type Orbitals as a basis functions in matrix method correctly? 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. Connect and share knowledge within a single location that is structured and easy to search. Therefore, you need to change it to long long instead of long in windows for 64 bits. @DietrichEpp can you explain what is race condition with using. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, You should be doing int x = *((int *)arg); You are casting from void * to int that is why you get the warning. 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 trying to do in that line of code is check to make sure each character in my string is alphabetical. ^~~~~~~~~~~~~~~~~~~~ This will only compile if the destination type is long enough. Find centralized, trusted content and collaborate around the technologies you use most. Where does this (supposedly) Gibson quote come from? For the second example you can make sure that sizeof(int) <= sizeof(void *) by using a static_assert -- this way at least you'll get a notice about it. Example: int x=7, y=5; float z; z=x/y; /*Here the value of z is 1*/. to your account, [87/252] Compiling C object lib/libopenvswitch.a.p/odp-util.c.obj You think by casting it here that you are avoiding the problem! To avoid truncating your pointer, cast it to a type of identical size. What is the purpose of non-series Shimano components? Based on the design of this function, which modification is right. If the value is ever used as pointer again that will prove to be an extremely bad idea. As a result of the integer division 3/2 we get the value 1, which is of the int type. Yeah, the tutorial is doing it wrong. ^~~~~~~~~~~~~~~~~~~ Is it possible to create a concave light? Terrible solution. Well it does this because you are converting a 64 bits pointer to an 32 bits integer so you loose information. 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. Why does flowing off the end of a non-void function without returning a value not produce a compiler error? To learn more, see our tips on writing great answers. 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. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, "what happen when typcating normal variable to void* or any pointer variable?" ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' Error while setting app icon and launch image in xcode 5.1. 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. What is the purpose of non-series Shimano components? SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); 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. What happens if you typecast as unsigned first? I guess the other important fact is that the cast operator has higher precedence that the multiplication operator. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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. eg. Why is this sentence from The Great Gatsby grammatical? How to use Slater Type Orbitals as a basis functions in matrix method correctly? Put your define inside a bracket: without a problem. Find centralized, trusted content and collaborate around the technologies you use most. To learn more, see our tips on writing great answers. Use returnPtr[j] = (void *) ((long)ptr + i); ). Java Type Casting. Most answers just try to extract 32 useless bits out of the argument. *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 . XCode 5.1 is change all architecture to 64 bit. Or, they are all wrong. How do I force make/GCC to show me the commands? Thus as a result it may be less error prone to generate a pointer dynamcially and use that. 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 The result is the same as implicit conversion from the enum's underlying type to the destination type. Making statements based on opinion; back them up with references or personal experience. It is done by the compiler on its own, without any external trigger from the user. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. @DavidHeffernan, sane thread APIs wouldn't send integral data to the thread procedures, they would send pointers. 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. */ >> -bool >> +enum conversion_safety >> unsafe_conversion_p (tree type, tree expr, bool . Remembering to delete the pointer after use so that we don't leak. 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 Implicit Type Conversion is also known as 'automatic type conversion'. A long long would not work for 32bit systems and a long would not work for 64 bit Windows (while 64bit Unix and Unix-like systems like OS X use the LP64 data model, in which a long is 64bit, 64bit Windows uses the LLP64 data model, in which a long has a size of 32bit (http://en.wikipedia.org/wiki/64-bit_computing#64-bit_data_models)). You need to pass an actual pointer. Replacing broken pins/legs on a DIP IC package, AC Op-amp integrator with DC Gain Control in LTspice. void* -> integer -> void* rather than integer -> void* -> integer. Converting a pointer to an integer whose result cannot represented in the integer type is undefined behavior is C and prohibited in C++. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? To learn more, see our tips on writing great answers. RNINGS" "-D_CRT_SECURE_NO_DEPRECATE" -MD -MQ lib/libopenvswitch.a.p/odp-util.c.obj -MF "lib\libopenvswitch.a.p\odp-util.c.obj.d" -o lib/libopenvswitch.a.p/od The main point is: a pointer has a platform dependent size. Click to see the query in the CodeQL repository. Safe downcast may be done with dynamic_cast. It was derived from the BCPL, and the name of the b language is possibly from the BCPL contraction. The following behavior-changing defect reports were applied retroactively to previously published C++ standards. 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. Please help me compile Chez Scheme. If your code has the chance to ever be ported to some platform where this doesn't hold, this won't work. casting from int to void* and back to int. This allows you to reinterpret the void * as an int. equal to the original pointer: First you are using a define, which is not a variable. Projects. 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. And when assigning to a void pointer, all type information is lost. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Why is there a voltage on my HDMI and coaxial cables? pthread create managing values generated in function (in c), Establishing TCP socket connection between PHP client and C server on Ubuntu. Here, the Java first converts the int type data into the double type. I have a function with prototype void* myFcn(void* arg) which is used as the starting point for a pthread. ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' If int is no larger than pointer to void then one way to store the value is by simply copying the bytes: int i . 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; In such condition type conversion (type promotion) takes place to avoid loss of data. The reinterpret_cast makes the int the size of a pointer and the warning will stop. itch" "-I..\include\windows" "-Iinclude" "-I..\include" "-I..\datapath-windows\include" "-IC:\PTHREADS-BUILT\include" "-Xclang" "-fcolor-diagnostics" "-pipe" The difference between a and &a is the type. Can Martian regolith be easily melted with microwaves? Is it possible to create a concave light? 10) A prvalue of type pointer to void (possibly cv-qualified) can be converted to pointer to any object type. Whats the grammar of "For those whose stories they are"? 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. There is absolutely not gurantee that sizeof(int) <= sizeof(void*). To subscribe to this RSS feed, copy and paste this URL into your RSS reader. SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); You could use this code, and it would do the same thing as casting ptr to (char*). How to use Slater Type Orbitals as a basis functions in matrix method correctly? (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 Replacing broken pins/legs on a DIP IC package, How to handle a hobby that makes income in US. Does Counterspell prevent from any further spells being cast on a given turn? The correct answer is, if one does not mind losing data precision. @BlueMoon Thanks a lot! ../lib/odp-util.c:5601:9: note: expanded from macro 'SCAN_PUT' B language was designed to develop . 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. If not, check the pointer size on your platform, define these typedefs accordingly yourself and use them. Unless you have a valid address at that value, you are going to invoke undefined behaviour when try to use that pointer. What video game is Charlie playing in Poker Face S01E07? How to convert a factor to integer\numeric without loss of information? In this case, casting the pointer back to an integer is meaningless, because . Yeah, the tutorial is doing it wrong. ^~~~~~~~~~~~~~~~~~~~ Press question mark to learn the rest of the keyboard shortcuts. : iPhone Retina 4-inch 64-bit) is selected. "-D_FILE_OFFSET_BITS=64" "-Wall" "-Winvalid-pch" "-g" "-Wthread-safety" "-Wno-microsoft-enum-forward-reference" "-Wno-unused-function" "-Wno-sometimes-unini ../lib/odp-util.c:5603:13: note: expanded from macro 'SCAN_PUT' @kshegunov said in Number Type Cast: const void * x; int y = int (x); compiles just fine. Now, what happens when I run it with the thread sanitizer? How to notate a grace note at the start of a bar with lilypond? Sign up for a free GitHub account to open an issue and contact its maintainers and the community. Use #include to define it. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Connect and share knowledge within a single location that is structured and easy to search. Well occasionally send you account related emails. C++ how to get the address stored in a void pointer? And in this context, it is very very very common to see programmers lazily type cast the. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? If we want to get the exact value of 7/5 then we need explicit casting from int to float: Example: int x=7, y=5; You use the address-of operator & to do that. A cast converts an object or value from one type to another. For the Nozomi from Shinagawa to Osaka, say on a Saturday afternoon, would tickets/seats typically be available - or would you need to book? But then you need to cast your arguments inside your thread function which is quite unsafe cf. By clicking Sign up for GitHub, you agree to our terms of service and But the problem has still happened. He should pass the address of the integer, the thread should get that address, Note: This is only appropriate is you cast the. How do I count the number of sentences in C using ". Thanks for pointing that out. Such pointers can be stored in 32-bit data types (for instance, int, DWORD). 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. 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. I assumed that gcc makes a 65536 out of my define, but I was wrong. Sign in Then i can continue compiling. 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. In the case of Widening Type Casting, the lower data type (having smaller size) is converted into the higher data type (having larger size). 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. 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 ) Making statements based on opinion; back them up with references or personal experience. Since gcc compiles that you are performing arithmetic between void* and an int (1024). What is the point of Thrower's Bandolier? Hence there is no loss in data. returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size); But I don't want to edit code in "EAGLView.mm" because it's a "library file". 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 need to cast the void* pointer to a char* pointer - and then dereference that char* pointer to give you the char that it points to! 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. 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. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Do new devs get fired if they can't solve a certain bug? converted back to pointer to void, and the result will compare equal 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. Visit Microsoft Q&A to post new questions. But this code pass the normal variable .. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. 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. linux c-pthreads: problem with local variables. If this is the data to a thread procedure, then you quite commonly want to pass by value. */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j; returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size); for (i=0, j=0; j returnPtr[j] = (void *) (ptr + i); // <<< Compile Errors, Error1error C2036: 'void *' : unknown sizec:\temp\testone\lib\utils.c57, 2> returnPtr[j] = (void *) ((long*)ptr + i); // <<< No compile errors, 3> returnPtr[j] = (void *) ((char*)ptr + i); // <<< No compile errors. 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. return ((void **) returnPtr);} /* Matrix() */. I have looked around and can't seem to find any information on how to do this. - the incident has nothing to do with me; can I use this this way? As Ferruccio said, int must be replaced with intptr_t to make the program meaningful. Already on GitHub? 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. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Infact I know several systems where that does not hold. You may declare a const int variable and cast its reference to the void*. A sane compiler may throw a warning on lines like this but by no way it should throw an error, because this code is NOT wrong, it is just potentially error-prone, but can be perfectly valid. A cast is a way of explicitly informing the compiler that you intend to make the conversion and that you are aware that data loss might occur, or the cast may fail at run time. 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. Getting Command /bin/sh failed with exit code 65 Error with Xcode 5.1 . If the function had the correct signature you would not need to cast it explicitly. Why is there a voltage on my HDMI and coaxial cables? I usually have all automatic conversion warnings effective when developing in C, and I use explicit casting in order to suppress a specific . For example, if you want to store a 'long' value into a simple integer then you can type cast 'long' to 'int'. If you are planning to use pthreads and you are planning to pass the pass function to pthread_create, you have to malloc/free the arguments you are planning to use (even if the threaded function just need a single int). Whats the grammar of "For those whose stories they are"? My code is all over the place now but I appreciate you all helping me on my journey to mastery! 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 does casting to void* does when passing arguments to variadic functions? If you need to keep the returned address, just keep it as void*. You should perform type conversion based on 64bit build system because the type "int" supports only -32768 ~ 32768. Can I tell police to wait and call a lawyer when served with a search warrant? This is what the second warning is telling you. It solved my problem too. As for the stack, I've written a few libraries using pthreds, thus I don't agree that what you describe "is quite often the case". Connect and share knowledge within a single location that is structured and easy to search. 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. } SCAN_END_SINGLE(ATTR) To learn more, see our tips on writing great answers. On most platforms pointers and longs are the same size, but ints and pointers often are not the same size on 64bit platforms. . For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. Find centralized, trusted content and collaborate around the technologies you use most. then converted back to pointer to void, and the result will compare 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. Otherwise, if the original pointer value points to an object a, and there is an object b of the . 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. Anw, the project still build and run normally when i use Xcode 5.0 with iOS 7.0. How to get the error message from the error code returned by GetLastError()? In simple example code like this it's very easy to convince yourself that there's no problem, but in more elaborate real-world scenarios it's very easy to make this mistake inadvertently. Recovering from a blunder I made while emailing a professor. The dynamic_cast<>operator provides a way to check the actual type of a pointer to a polymorphic class. I need to convert the argument to an int for later use: The compiler (GCC version 4.2.4) returns the error: You can cast it to an intptr_t type. Changing the type of ids would be the cleanest solution, but I decided against it when being confronted with this issue myself, as it only introduced a lot of issues with other code that is relying on ids being an int-array. It generally takes place when in an expression more than one data type is present. All character types are to be converted to an integer. Even though what you say regarding the lifetime of the object is true, integral types are too limited for a generic API. You are right! Implementing From will result in the Into implementation but not vice-versa. with ids being an array of ints and touch being a pointer. How do I set, clear, and toggle a single bit? I need to cast the int from the first function so that I can use it as an argument for the second function. @LearnCocos2D: so, how can i "overcome" the error without editing any not-my-code or in-library-file lines? 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). You can convert the values from one type to another explicitly using the cast operator as follows (type_name) expression Are there tables of wastage rates for different fruit and veg? If your standard library (even if it is not C99) happens to provide these types - use them. static const void* M_OFFSET = (void*)64*1024; Since gcc compiles that you are performing arithmetic between void* and an int ( 1024 ). But I'm nitpicking .. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. We have to pass address of the variable to the function because in function definition argument is pointer variable. I am an entry level C programmer. Connect and share knowledge within a single location that is structured and easy to search. Asking for help, clarification, or responding to other answers. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Using printf with a pointer to float gives an error, Meaning of int (*) (int *) = 5 (or any integer value), Casting int to void* loses precision, and what is the solution in required cases, Acidity of alcohols and basicity of amines. "-I.." "-Iinclude\openflow" "-I..\include\openflow" "-Iinclude\openvswitch" "-I..\include\openvsw For a fairly recent compiler (that supports C99) you should not store or represent address as plain int value. If it's anything like cocos2d-iphone v2.x and just based on this slice of code in a core class I wager it's safe to say that cocos2d-x 2.x also is not compatible with 64 bit code, and you can expect all kinds of issues (not just compile-time but also runtime). It is easier to understand and write than any other assembly language. I am compiling this program in linux gcc compiler.. Not the answer you're looking for? That's probably going to be true for most platforms you will ever encounter, but it's not a guarantee; it's implementation-dependent. If pointers are 64 bits and ints are 32 bits, an int is too small to hold a pointer value. The result is implementation-defined and typically yields the numeric address of the byte in memory that the pointer pointers to. Alternatively, if you choose to castthe ptr variableto (size_t) instead, then you don't need to worry about the pointer typeanymore. Connect and share knowledge within a single location that is structured and easy to search. Thanks for contributing an answer to Stack Overflow! And you can't pass a pointer to a stack based object from the other thread as it may no longer be valid. How to tell which packages are held back due to phased updates, Identify those arcade games from a 1983 Brazilian music video. Before I update Xcode, my project still can build and run normally with all devices. Asking for help, clarification, or responding to other answers. For example, the main thread could wait for all of the other threads to end before terminating. Note the difference between the type casting of a variable and type casting of a pointer. However, you are also casting the result of this operation to (void*).
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