By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. : iPhone Retina 4-inch 64-bit) is selected. Type casting is when you assign a value of one primitive data type to another type. actually no, as int my be a smaller type than a pointer ;-) But, of course with int64_t it works fine. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? Then i can continue compiling. AC Op-amp integrator with DC Gain Control in LTspice. 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.." "-Iinclude\openflow" "-I..\include\openflow" "-Iinclude\openvswitch" "-I..\include\openvsw } SCAN_END_SINGLE(ATTR) Even though what you say regarding the lifetime of the object is true, integral types are too limited for a generic API. I have a function with prototype void* myFcn(void* arg) which is used as the starting point for a pthread. 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. @DietrichEpp can you explain what is race condition with using. Create an account to follow your favorite communities and start taking part in conversations. The value of float variable is= 37.75. It is easier to understand and write than any other assembly language. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. what does it mean to convert int to void* or vice versa? If you preorder a special airline meal (e.g. For integer casts in specific, using into() signals that . What is the purpose of this D-shaped ring at the base of the tongue on my hiking boots? ^~~~~~~~~~~~~~~~~~~~~ Casting arguments inside the function is a lot safer. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. You are getting warnings due to casting a void* to a type of a different size. It's always a good practice to put your #define's in brackets to avoid such surprise. This is memory reinterpretation - a completely unacceptable way to do what the OP is trying to do. Therefore it is perfectly valid for the compiler to throw an error for a line like. ncdu: What's going on with this second size column? 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). 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. You should perform type conversion based on 64bit build system because the type "int" supports only -32768 ~ 32768. For example, the main thread could wait for all of the other threads to end before terminating. (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. property that any valid pointer to void can be converted to this type, reinterpret_cast<void *>(42)). Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. But, sure, in that specific case you can pass a local variable address, type casting integer to void* [duplicate]. Typically, long or unsigned long is . @BlueMoon Thanks a lot! Using Kolmogorov complexity to measure difficulty of problems? You are getting warnings due to casting a void* to a type of a different size. To learn more, see our tips on writing great answers. Thanks for contributing an answer to Stack Overflow! warning C4311: 'type cast': pointer truncation from 'void *' to 'long' in ECPG test files. 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. (void *)i Error: cast to 'void *' from smaller integer type 'int'. An object pointer (including void*) or function pointer can be converted to an integer type using reinterpret_cast. 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. Why is there a voltage on my HDMI and coaxial cables? Linear regulator thermal information missing in datasheet. I am compiling this program in linux gcc compiler.. Is it possible to create a concave light? Star 675. rev2023.3.3.43278. Implementation-dependent. The proper way is to cast it to another pointer type. Using Kolmogorov complexity to measure difficulty of problems? What happens if you typecast as unsigned first? What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? ^~~~~~~~~~~~~~~~~~~ So you know you can cast it back like this. For the Nozomi from Shinagawa to Osaka, say on a Saturday afternoon, would tickets/seats typically be available - or would you need to book? 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. Otherwise, if the original pointer value points to an object a, and there is an object b of the . (i.e. Visit Microsoft Q&A to post new questions. Bulk update symbol size units from mm to map units in rule-based symbology. Don't do that. Not the answer you're looking for? The result is implementation-defined and typically yields the numeric address of the byte in memory that the pointer pointers to. 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. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Please unaccept the answer you have chosen as it is wrong (as the comments below it say) and will lead to bugs. I guess the other important fact is that the cast operator has higher precedence that the multiplication operator. Once you manage to make this cast, then what?! converted back to pointer to void, and the result will compare equal "-D_FILE_OFFSET_BITS=64" "-Wall" "-Winvalid-pch" "-g" "-Wthread-safety" "-Wno-microsoft-enum-forward-reference" "-Wno-unused-function" "-Wno-sometimes-unini To learn more, see our tips on writing great answers. ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] Remembering to delete the pointer after use so that we don't leak. 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). What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? 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. I agree passing a dynamically allocated pointer is fine (and I think the best way). The text was updated successfully, but these errors were encountered: You can only do this if you use a synchronization primitive to ensure that there is no race condition. Does melting sea ices rises global sea level? 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. The problem is not with casting, but with the target type loosing half of the pointer. No sense in writing a few dozen lines of extra code just to get a bunch of numbered threads. If pointers are 64 bits and ints are 32 bits, an int is too small to hold a pointer value. ../lib/odp-util.c:5489:33: note: expanded from macro 'SCAN_PUT_ATTR' Offline ImPer Westermark over 11 years ago in reply to Andy Neil Except that you sometimes stores an integer in the pointer itself. If your standard library (even if it is not C99) happens to provide these types - use them. This will only compile if the destination type is long enough. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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 Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Most answers just try to extract 32 useless bits out of the argument. ERROR: incompatible integer to pointer conversion assigning to 'string' (aka 'char *') from 'int', error: cast to 'string' (aka 'char *') from smaller integer type 'int' [-Werror,-Wint-to-pointer-cast], error: incompatible integer to pointer conversion assigning to 'string' (aka 'char *') from 'int' C, warning: initialization of 'unsigned char' from 'uint8_t *' {aka 'unsigned char *'} makes integer from pointer without a cast [-Wint-conversion], Minimising the environmental effects of my dyson brain. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? static const void* M_OFFSET = (void*)64*1024; Since gcc compiles that you are performing arithmetic between void* and an int ( 1024 ). I'm using cocos2d-x-2.2.2. I would create a structure and pass that as void* to pthread_create. From that point on, you are dealing with 32 bits. Unless you have a valid address at that value, you are going to invoke undefined behaviour when try to use that pointer. 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. Surely the solution is to change the type of ids from int to type that is sufficiently large to hold a pointer. It is commonly called a pointer to T and its type is T*. I'm trying to create a void* from an int. p-util.c.obj "-c" ../lib/odp-util.c ^~~~~~~~~~~~~~~~~~~~~ Whats the grammar of "For those whose stories they are"? what happens when we typecast normal variable to void* or any pointer variable? If you write ((char*)ptr + 1), it will advance the pointer 1 byte, because a "char" is 1 byte. Recovering from a blunder I made while emailing a professor. The only exception is exotic systems with the SILP64 data model, where the size of int is also 64 bits. The subreddit for the C programming language, Press J to jump to the feed. But this code pass the normal variable .. Can I tell police to wait and call a lawyer when served with a search warrant? Thanks for pointing that out. ../lib/odp-util.c:5603:13: note: expanded from macro 'SCAN_PUT' Now, what happens when I run it with the thread sanitizer? [that could be a TODO - not to delay solving the ICE]. In this case, casting the pointer back to an integer is meaningless, because . Returns a value of type new-type. Is it possible to create a concave light? 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. rev2023.3.3.43278. It was derived from the BCPL, and the name of the b language is possibly from the BCPL contraction. No idea how it amassed 27 upvotes?! 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. The problem was there before, you just are being notified of it. Thanks for contributing an answer to Stack Overflow! Before I update Xcode, my project still can build and run normally with all devices. How to tell which packages are held back due to phased updates, Identify those arcade games from a 1983 Brazilian music video. C / C++ Forums on Bytes. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? you can just change architecture to support 32 bit compilation by all below in in Build Settings. 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 ) Does Counterspell prevent from any further spells being cast on a given turn? Example: int x=7, y=5; float z; z=x/y; /*Here the value of z is 1*/. Why does Mister Mxyzptlk need to have a weakness in the comics? 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 Notifications. itch" "-I..\include\windows" "-Iinclude" "-I..\include" "-I..\datapath-windows\include" "-IC:\PTHREADS-BUILT\include" "-Xclang" "-fcolor-diagnostics" "-pipe" Yeah, the tutorial is doing it wrong. 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. Share Improve this answer Follow answered May 6, 2018 at 7:24 Rahul It solved my problem too. Why is this sentence from The Great Gatsby grammatical? How Intuit democratizes AI development across teams through reusability. 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. What video game is Charlie playing in Poker Face S01E07? (int) pthread_self() 64int48intuintptr_t (unsigned int) But I'm nitpicking .. 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 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Not the answer you're looking for? Where does this (supposedly) Gibson quote come from? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. You cannot just cast the 32-bit variable to a pointer, because that pointer on a 64-bit machine is twice as long. 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. . 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. that any valid pointer to void can be converted to this type, then what does it mean to convert int to void* or vice versa? ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I usually have all automatic conversion warnings effective when developing in C, and I use explicit casting in order to suppress a specific . SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); SQL Server does not automatically promote . Sign up for a free GitHub account to open an issue and contact its maintainers and the community. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. XCode 5.1 is change all architecture to 64 bit. Remarks. Please help me compile Chez Scheme. Whats the grammar of "For those whose stories they are"? To perform a cast, specify the type that you are casting to in parentheses in front of the value or variable to be converted. What you do here is undefined behavior, and undefined behavior of very practical sort. You are just making it bigger by tricking the compiler and the ABI. 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. SCAN_PUT(ATTR, NULL); Since gcc compiles that you are performing arithmetic between void* and an int (1024). Mutually exclusive execution using std::atomic? 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. Have a question about this project? A nit: in your version, the cast to void * is unnecessary. Or, they are all wrong. 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). 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. Only the following conversions can be done with static_cast, except when such conversions would cast away constness or volatility. Well it does this because you are converting a 64 bits pointer to an 32 bits integer so you loose information. My code is all over the place now but I appreciate you all helping me on my journey to mastery! If not, check the pointer size on your platform, define these typedefs accordingly yourself and use them. Where does this (supposedly) Gibson quote come from? @DavidHeffernan, sane thread APIs wouldn't send integral data to the thread procedures, they would send pointers. What is the difference between const int*, const int * const, and int const *? (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 Find centralized, trusted content and collaborate around the technologies you use most. Asking for help, clarification, or responding to other answers. ../lib/odp-util.c:5601:9: note: expanded from macro 'SCAN_PUT' Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin? The difference between the phonemes /p/ and /b/ in Japanese. 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). 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. Connect and share knowledge within a single location that is structured and easy to search. The main point is: a pointer has a platform dependent size. Since the 'size' argument for your function is the number of bytes each element in the array needs, I think casting the pointerto (char*) is appropriate. Thank you all for your feedback. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. There is absolutely not gurantee that sizeof(int) <= sizeof(void*). How to make compiler not show int to void pointer cast warnings, incompatible pointer types assigning to 'void (*)(void *)' from 'int (int *)'. Is a PhD visitor considered as a visiting scholar. */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. ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] Using indicator constraint with two variables. How do I check if a string represents a number (float or int)? 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; You use the address-of operator & to do that. I have looked around and can't seem to find any information on how to do this. Replacing broken pins/legs on a DIP IC package, AC Op-amp integrator with DC Gain Control in LTspice. 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. Here is my code: I already tried (void*)M_TABLE_SIZE but then I get an error that I cannot use the * operator. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. However, you are also casting the result of this operation to (void*). The difference between the phonemes /p/ and /b/ in Japanese, Styling contours by colour and by line thickness in QGIS. rev2023.3.3.43278. 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; whether it was an actual problem is a different matter though. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. Why do small African island nations perform better than African continental nations, considering democracy and human development?
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