cast to void *' from smaller integer type 'int

@DavidHeffernan I rephrased that sentence a little. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. From the question I presume the OP does. I agree passing a dynamically allocated pointer is fine (and I think the best way). For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. Don't do that. The mapping in pointer<->integer casts is implementation defined, but the intent was that if the pointer type is large enough and isn't forcefully aligned (, But that's different. Why did Ukraine abstain from the UNHRC vote on China? Projects. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. You think by casting it here that you are avoiding the problem! Do new devs get fired if they can't solve a certain bug? Such pointers can be stored in 32-bit data types (for instance, int, DWORD). itch" "-I..\include\windows" "-Iinclude" "-I..\include" "-I..\datapath-windows\include" "-IC:\PTHREADS-BUILT\include" "-Xclang" "-fcolor-diagnostics" "-pipe" The main point is: a pointer has a platform dependent size. 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. 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 proper way is to cast it to another pointer type. This is known as implicit type casting or type promotion, compiler automatically converts smaller data type to larger data type. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. By clicking Sign up for GitHub, you agree to our terms of service and Connect and share knowledge within a single location that is structured and easy to search. That could create all kinds of trouble. Where does this (supposedly) Gibson quote come from? 1. (int*)Pc = pa; After the execution of the above code all the three pointers, i.e., Pa, Pd, and Pc, point to the value 150. 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. Why do small African island nations perform better than African continental nations, considering democracy and human development? There are ways to prevent this: pass a dynamic allocated argument if your not the passing thread is not static or if your argument is a local variable, otherwise there is no issue. Otherwise, if the original pointer value points to an object a, and there is an object b of the . A void pointer can be really useful if the programmer is not sure about the data type of data inputted by the end user. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? But I'm nitpicking .. To learn more, see our tips on writing great answers. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? 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". What is the point of Thrower's Bandolier? that any valid pointer to void can be converted to this type, then 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. Find centralized, trusted content and collaborate around the technologies you use most. Mutually exclusive execution using std::atomic? How do I align things in the following tabular environment? you can just change architecture to support 32 bit compilation by all below in in Build Settings. But then you need to cast your arguments inside your thread function which is quite unsafe cf. Using Kolmogorov complexity to measure difficulty of problems? Can Martian regolith be easily melted with microwaves? I have a two functions, one that returns an int, and one that takes a const void* as an argument. Making statements based on opinion; back them up with references or personal experience. Only the following conversions can be done with static_cast, except when such conversions would cast away constness or volatility. The preprocessor will replace your code by this: This is unlikely what you are trying to do. We have to pass address of the variable to the function because in function definition argument is pointer variable. Asking for help, clarification, or responding to other answers. If the value is ever used as pointer again that will prove to be an extremely bad idea. "I think what you should do is actually pass the address of the variable to the function" Not necessarily. You are getting warnings due to casting a void* to a type of a different size. Why does setupterm terminate the program? Java Type Casting. Whats the grammar of "For those whose stories they are"? ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. Even though what you say regarding the lifetime of the object is true, integral types are too limited for a generic API. Making statements based on opinion; back them up with references or personal experience. This will only compile if the destination type is long enough. 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. Get the address of a callback function to call dynamically in C++, error: call of overloaded function ambiguous, error: cast from to unsigned int loses precision [-fpermissive]. Where does this (supposedly) Gibson quote come from? 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. It is commonly called a pointer to T and its type is T*. This is an old C callback mechanism so you can't change that. 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. rev2023.3.3.43278. But the problem has still happened. linux c-pthreads: problem with local variables. Connect and share knowledge within a single location that is structured and easy to search. The high-order 9 bits of the number are used to hold a flag value, and the result is converted back into a pointer. Mutually exclusive execution using std::atomic? Surely the solution is to change the type of ids from int to type that is sufficiently large to hold a pointer. Is pthread_join a must when using pthread in linux? 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. In such a case the programmer can use a void pointer to point to the location of the unknown data type. This is memory reinterpretation - a completely unacceptable way to do what the OP is trying to do. Converts between types using a combination of implicit and user-defined conversions. Thanks for contributing an answer to Stack Overflow! to the original pointer: The following type designates an unsigned integer type with the Basically its a better version of (void *)i. Yesterday, I updated Xcode to the newest version (5.1 (5B130a)) to compatible with iOS 7.1. This method will not work on 64 bit Big Endian platform, so it unnecessarily breaks portability. There is no "correct" way to store a 64-bit pointer in an 32-bit integer. A cast specifies a conversion from one type to another. You are correct, but cocos actually only uses that address as a unique id. } SCAN_END_SINGLE(ATTR) What does it mean to convert int to void* or vice versa? 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. 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. 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). 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 Java, there are two types of casting: Widening Casting (automatically) - converting a smaller type to a larger type size. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. converted back to pointer to void, and the result will compare equal ), Styling contours by colour and by line thickness in QGIS. I have looked around and can't seem to find any information on how to do this. 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. "After the incident", I started to be more careful not to trip over things. ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' But gcc always give me a warning, that i cannot cast an int to a void*. Visit Microsoft Q&A to post new questions. You use the address-of operator & to do that. It was derived from the BCPL, and the name of the b language is possibly from the BCPL contraction. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. What you do here is undefined behavior, and undefined behavior of very practical sort. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ "clang" "-Ilib\libopenvswitch.a.p" "-Ilib" "-I..\lib" "-I." 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). Then i can continue compiling. ^~~~~~~~~~~~~~~~~~~ . How Intuit democratizes AI development across teams through reusability. ^~~~~~~~~~~~~~~~~~~~ a is of type int[4], which can be implicitly cast to int* (ie, a pointer to an int) &a is of type int(*)[4] (ie: a pointer to an array of 4 ints). @Shahbaz you could but I will not suggest to a C newbie to use globals. Implicit Type Conversion is also known as 'automatic type conversion'. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Why is there a voltage on my HDMI and coaxial cables? casting from int to void* and back to int. a cast of which the programmer should be aware of what (s)he is doing. 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. The subreddit for the C programming language, Press J to jump to the feed. Losing bytes like thisis called 'truncation', and that's what the first warning is telling you. As with all cast expressions, the result is: Two objects a and b are pointer-interconvertible if: static_cast may also be used to disambiguate function overloads by performing a function-to-pointer conversion to specific type, as in. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? whether it was an actual problem is a different matter though. void* -> integer -> void* rather than integer -> void* -> integer. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? 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. Bulk update symbol size units from mm to map units in rule-based symbology. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. this way you won't get any warning. *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 . 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 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 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 don't see how anything bad can happen . Mutually exclusive execution using std::atomic? Why does Mister Mxyzptlk need to have a weakness in the comics? The only alternative is really to take time and fix all 64-bit code issues, of which there may be some non-trivial issues. rev2023.3.3.43278. The following program casts a double to an int. All float types are to be converted to double. In this case, casting the pointer back to an integer is meaningless, because . Does Counterspell prevent from any further spells being cast on a given turn? rev2023.3.3.43278. 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). [] ExplanatioUnlike static_cast, but like const_cast, the reinterpret_cast expression does not compile to any CPU instructions (except when converting between integers and pointers or on obscure architectures where pointer representation depends on its type). ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] 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. How can this new ban on drag possibly be considered constitutional? The most general answer is - in no way. 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. So you could do this: Note: As sbi points out this would require a change on the OP call to create the thread. The text was updated successfully, but these errors were encountered: You signed in with another tab or window. If your standard library (even if it is not C99) happens to provide these types - use them. Use #include to define it. lexborisov Modest Public. Getting Command /bin/sh failed with exit code 65 Error with Xcode 5.1 . 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 While working with Threads in C, I'm facing the warning, "warning: cast to pointer from integer of different size". To avoid truncating your pointer, cast it to a type of identical size. . 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. ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' p-util.c.obj "-c" ../lib/odp-util.c ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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. I am an entry level C programmer. The difference between the phonemes /p/ and /b/ in Japanese. ^~~~~~~~~~~~~~~~~~~~ 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". then converted back to pointer to void, and the result will compare rev2023.3.3.43278. Acidity of alcohols and basicity of amines. Hence there is no loss in data. Sign in C / C++ Forums on Bytes. This is flat out wrong. -1, Uggh. This is why you got Error 1 C2036, from your post. @kshegunov said in Number Type Cast: const void * x; int y = int (x); compiles just fine. @LearnCocos2D: so, how can i "overcome" the error without editing any not-my-code or in-library-file lines? How to use Slater Type Orbitals as a basis functions in matrix method correctly? vegan) just to try it, does this inconvenience the caterers and staff? Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin? In such condition type conversion (type promotion) takes place to avoid loss of data. To learn more, see our tips on writing great answers. unsigned long call_fn = (unsigned long)FUNC; ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Thank you all for your feedback. On most platforms pointers and longs are the same size, but ints and pointers often are not the same size on 64bit platforms. 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;. Wrong. GitHub. 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;. @Martin York: No, it doesn't depend on endiannness. Connect and share knowledge within a single location that is structured and easy to search. pthread create managing values generated in function (in c), Establishing TCP socket connection between PHP client and C server on Ubuntu. What is the purpose of non-series Shimano components? */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j; Update: Today, i download the latest version of cocos2d-x (cocos2d-x 2.2.3). I am compiling this program in linux gcc compiler.. Thanks. (int) pthread_self() 64int48intuintptr_t (unsigned int) C99 defines the types "intptr_t" and "uintptr_t" which do . property that any valid pointer to void can be converted to this type, As Ferruccio said, int must be replaced with intptr_t to make the program meaningful. vegan) just to try it, does this inconvenience the caterers and staff? 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). Remembering to delete the pointer after use so that we don't leak. Did i have to face to unexpected runtime issues, i guess not, i've found another discussion on this -. I recall there was a TreeNode(int) early on prior to 1.0 release I can't remember why I removed it, if I should felt it was easy enough to cast to (void*) or if it was because it created type inference conflict at the call site. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. If the destination type is bool, this is a boolean conversion (see below). Windows has 32 bit long only on 64 bit as well. I cannot reverse my upvote of user384706's answer, but it's wrong. You are just making it bigger by tricking the compiler and the ABI. use $(ARCHS_STANDARD_32_BIT) at Architecture instead of $(ARCHS_STANDARD). 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. This page has been accessed 1,655,678 times. What happens if you typecast as unsigned first? : iPhone Retina 4-inch 64-bit) is selected. Safe downcast may be done with dynamic_cast. 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. That's not a good idea if the original object (that was cast to void*) was an integer. 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. Is it possible to create a concave light? Not the answer you're looking for? 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. There's no proper way to cast this to int in general case. Yeah, the tutorial is doing it wrong. returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size); It's an int type guaranteed to be big enough to contain a pointer. Asking for help, clarification, or responding to other answers. 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. ncdu: What's going on with this second size column? How Intuit democratizes AI development across teams through reusability. 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.. Maybe you can try this too. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); byte -> short -> char -> int -> long -> float -> double. Using indicator constraint with two variables. Functions return bigint only if the parameter expression is a bigint data type. But assuming that it is, as long as the caller and the callee agree, you can do that sort of thing. Alternatively, if you choose to castthe ptr variableto (size_t) instead, then you don't need to worry about the pointer typeanymore. actually no, as int my be a smaller type than a pointer ;-) But, of course with int64_t it works fine. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Find centralized, trusted content and collaborate around the technologies you use most. And, most of these will not even work on gcc4. Connect and share knowledge within a single location that is structured and easy to search. 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. eg. 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 And when assigning to a void pointer, all type information is lost. @jackdoe: It's a waste of human life to write code that "you may need in the future". Before I update Xcode, my project still can build and run normally with all devices. So make sure you understand what you are doing! You are right! If your standard library (even if it is not C99) happens to provide these types - use them. */ >> -bool >> +enum conversion_safety >> unsafe_conversion_p (tree type, tree expr, bool . Keep in mind that thrArg should exist till the myFcn() uses it. To be honest, I think, clang is too restrictive here. Floating-point conversions It solved my problem too. for saving RAM), use union, and make sure, if the mem address is treated as an int only if you know it was last set as an int. Just edited. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. 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. Does Counterspell prevent from any further spells being cast on a given turn? Type casting is when you assign a value of one primitive data type to another type. I guess the other important fact is that the cast operator has higher precedence that the multiplication operator. I usually have all automatic conversion warnings effective when developing in C, and I use explicit casting in order to suppress a specific . 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. If you need to keep the returned address, just keep it as void*. No sense in writing a few dozen lines of extra code just to get a bunch of numbered threads.

When You Don't Respond To A Narcissist Text, Accident On Casper Mountain, Articles C