cast to void *' from smaller integer type 'int

You can also convert values from one type to another explicitly using the cast operator (see Chapter 5 ): ( type_name) expression In the following example, the cast operator causes the division of one integer variable by another to be performed as a floating-point operation: int sum = 22, count = 5; double mean = (double)sum / count; Connect and share knowledge within a single location that is structured and easy to search. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. That's probably going to be true for most platforms you will ever encounter, but it's not a guarantee; it's implementation-dependent. Create an account to follow your favorite communities and start taking part in conversations. I am compiling this program in linux gcc compiler.. 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]. This is an old C callback mechanism so you can't change that. That could create all kinds of trouble. Bulk update symbol size units from mm to map units in rule-based symbology. Surely the solution is to change the type of ids from int to type that is sufficiently large to hold a pointer. The dynamic_cast<>operator provides a way to check the actual type of a pointer to a polymorphic class. The int data type is the primary integer data type in SQL Server. Why did Ukraine abstain from the UNHRC vote on China? B language was designed to develop . with ids being an array of ints and touch being a pointer. What is the purpose of this D-shaped ring at the base of the tongue on my hiking boots? Functions return bigint only if the parameter expression is a bigint data type. SCAN_PUT(ATTR, NULL); Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? If you write ((char*)ptr + 1), it will advance the pointer 1 byte, because a "char" is 1 byte. I would create a structure and pass that as void* to pthread_create. Connect and share knowledge within a single location that is structured and easy to search. How to use Slater Type Orbitals as a basis functions in matrix method correctly? 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. There is no "correct" way to store a 64-bit pointer in an 32-bit integer. 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". But the problem has still happened. Converting one datatype into another is known as type casting or, type-conversion. This will only compile if the destination type is long enough. linux c-pthreads: problem with local variables. How do I set, clear, and toggle a single bit? this way I convert an int to a void* which is much better than converting a void* to an int. 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. 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. 7.1 New Cast Operations The C++ standard defines new cast operations that provide finer control than previous cast operations. 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. To perform a cast, specify the type that you are casting to in parentheses in front of the value or variable to be converted. Pd = Pa; Similarly, Pc may be type cast to type int and assigned the value Pa. 1. Why does setupterm terminate the program? You are right! ), For those who are interested. To learn more, see our tips on writing great answers. 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. Passing arguments to pthread_create - invalid conversion from void(*)() to void(*)(void*). 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). ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' Here, the Java first converts the int type data into the double type. itch" "-I..\include\windows" "-Iinclude" "-I..\include" "-I..\datapath-windows\include" "-IC:\PTHREADS-BUILT\include" "-Xclang" "-fcolor-diagnostics" "-pipe" Thank you all for your feedback. Please unaccept the answer you have chosen as it is wrong (as the comments below it say) and will lead to bugs. Does ZnSO4 + H2 at high pressure reverses to Zn + H2SO4? @LearnCocos2D: so, how can i "overcome" the error without editing any not-my-code or in-library-file lines? What is the difference between const int*, const int * const, and int const *? Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Setting a buffer of char* with intermediate casting to int*. The text was updated successfully, but these errors were encountered: You signed in with another tab or window. In such a case the programmer can use a void pointer to point to the location of the unknown data type. It solved my problem too. My code is all over the place now but I appreciate you all helping me on my journey to mastery! 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. If your standard library (even if it is not C99) happens to provide these types - use them. Can I tell police to wait and call a lawyer when served with a search warrant? Whats the grammar of "For those whose stories they are"? Java Type Casting. 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. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Making statements based on opinion; back them up with references or personal experience. 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' Losing bytes like thisis called 'truncation', and that's what the first warning is telling you. */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j; There's no proper way to cast this to int in general case. If the sizes are different then endianess comes into play. How to notate a grace note at the start of a bar with lilypond? ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ How to tell which packages are held back due to phased updates, Identify those arcade games from a 1983 Brazilian music video. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? The result is the same as implicit conversion from the enum's underlying type to the destination type. How to make compiler not show int to void pointer cast warnings, incompatible pointer types assigning to 'void (*)(void *)' from 'int (int *)'. As a result of the integer division 3/2 we get the value 1, which is of the int type. Find centralized, trusted content and collaborate around the technologies you use most. 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. If the function had the correct signature you would not need to cast it explicitly. I think the solution 3> should be the correct one. A pointer converted to an integer of sufficient size and back to the same pointer type is guaranteed to have its original value, otherwise the resulting pointer cannot be dereferenced safely ( the round-trip conversion in the opposite direction is not guaranteed [.]) 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. Converts between types using a combination of implicit and user-defined conversions. It's an int type guaranteed to be big enough to contain a pointer. The only alternative is really to take time and fix all 64-bit code issues, of which there may be some non-trivial issues. You are correct, but cocos actually only uses that address as a unique id. "because the type "int" supports only -32768 ~ 32768" This is not true for any modern desktop or mobile OS or any OS that is targeted by cocos2d-x. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. "I think what you should do is actually pass the address of the variable to the function" Not necessarily. Why do small African island nations perform better than African continental nations, considering democracy and human development? If you preorder a special airline meal (e.g. Does Counterspell prevent from any further spells being cast on a given turn? Otherwise, if the original pointer value points to an object a, and there is an object b of the . you can just change architecture to support 32 bit compilation by all below in in Build Settings. Asking for help, clarification, or responding to other answers. Thanks for contributing an answer to Stack Overflow! By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. How do I align things in the following tabular environment? The text was updated successfully, but these errors were encountered: Remarks. 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. Asking for help, clarification, or responding to other answers. 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. equal to the original pointer: First you are using a define, which is not a variable. Not the answer you're looking for? You need to pass an actual pointer. But this code pass the normal variable .. You can fix this error by replacing this line of code. rev2023.3.3.43278. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? Yeah, the tutorial is doing it wrong. ", "!"? And, most of these will not even work on gcc4. Usually that means the pointer is allocated with. ), Styling contours by colour and by line thickness in QGIS. Basically its a better version of (void *)i. should we also have a diagnostic for the (presumed) user error? If pointers are 64 bits and ints are 32 bits, an int is too small to hold a pointer value. 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. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Not the answer you're looking for? to your account, [87/252] Compiling C object lib/libopenvswitch.a.p/odp-util.c.obj Before I update Xcode, my project still can build and run normally with all devices. 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. windows meson: cast to smaller integer type 'unsigned long' from 'void *'. If you need to keep the returned address, just keep it as void*. It is easier to understand and write than any other assembly language. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. error: comparison between pointer and integer ('int' and 'string' (aka 'char *')), CS50 Caesar program is working but check50 says it isn't. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Casting arguments inside the function is a lot safer. AC Op-amp integrator with DC Gain Control in LTspice. ../lib/odp-util.c:5603:13: note: expanded from macro 'SCAN_PUT' So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. Using Kolmogorov complexity to measure difficulty of problems? You can convert the values from one type to another explicitly using the cast operator as follows (type_name) expression I don't see how anything bad can happen . Converting a pointer to an integer whose result cannot represented in the integer type is undefined behavior is C and prohibited in C++. STR34-C. Disconnect between goals and daily tasksIs it me, or the industry? @DietrichEpp can you explain what is race condition with using. long guarantees a pointer size on Linux on any machine. Fork 63. @Xax: Here's a fixed version, without the race condition: gist.github.com/depp/241d6f839b799042c409, gist.github.com/depp/3f04508a88a114734195, How Intuit democratizes AI development across teams through reusability. 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;. I am an entry level C programmer. (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. The subreddit for the C programming language, Press J to jump to the feed. ^~~~~~~~~~~~~~~~~~~~~ to the original pointer: The following type designates an unsigned integer type with the Star 675. ^~~~~~~~~~~~~~~~~~~~~ [] 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). If you are going to pass the address you typically need to exert some more control over the lifetime of the object. static const void* M_OFFSET = (void*)64*1024; Since gcc compiles that you are performing arithmetic between void* and an int ( 1024 ). ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] The pointer doesn't actually point to anything, but it's the result of an earlier cast from an integer to a pointer (e.g. This is what the second warning is telling you. Your first example is risky because you have to be very careful about the object lifetimes. You think by casting it here that you are avoiding the problem! Replacing broken pins/legs on a DIP IC package, How to handle a hobby that makes income in US. } SCAN_END_SINGLE(ATTR) A cast converts an object or value from one type to another. By clicking Sign up for GitHub, you agree to our terms of service and To avoid truncating your pointer, cast it to a type of identical size. If you preorder a special airline meal (e.g. Or, they are all wrong. whether it was an actual problem is a different matter though. 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 You just need to suppress the warning, and this will do it: This may offend your sensibilities, but it's very short and has no race conditions (as you'd have if you used &i). casting from int to void* and back to int. LLNL's tutorial is bad and they should feel bad. actually no, as int my be a smaller type than a pointer ;-) But, of course with int64_t it works fine. even though the compiler doesn't know you only ever pass myFcn to pthread_create in conjunction with an integer. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? What does it mean to convert int to void* or vice versa? use $(ARCHS_STANDARD_32_BIT) at Architecture instead of $(ARCHS_STANDARD). Such pointers can be stored in 32-bit data types (for instance, int, DWORD). I'm using cocos2d-x-2.2.2. Difficulties with estimation of epsilon-delta limit proof. 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. Hence there is no loss in data. 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. B programing language is a language based on basic combined programming or a BCPL, and it is the precursor of the C programming language. On all of them int is 32bit, not 16bit. Find centralized, trusted content and collaborate around the technologies you use most. 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. As was pointed out by Martin, this presumes that sizeof(void*)>=sizeof(int). error: cast from pointer to smaller type 'unsigned int' loses information. C99 defines the types "intptr_t" and "uintptr_t" which do . rev2023.3.3.43278. Again, all of the answers above missed the point badly. (void *)i Error: cast to 'void *' from smaller integer type 'int'. There is absolutely not gurantee that sizeof(int) <= sizeof(void*). Did i have to face to unexpected runtime issues, i guess not, i've found another discussion on this -. Share Improve this answer Follow answered May 6, 2018 at 7:24 Rahul 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). Error while setting app icon and launch image in xcode 5.1. I usually have all automatic conversion warnings effective when developing in C, and I use explicit casting in order to suppress a specific . In the case of Widening Type Casting, the lower data type (having smaller size) is converted into the higher data type (having larger size). From the question I presume the OP does. 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 ^~~~~~~~~~~~~~~~~~~~ You can only do this if you use a synchronization primitive to ensure that there is no race condition. Unless you have a valid address at that value, you are going to invoke undefined behaviour when try to use that pointer. (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. But I don't want to edit code in "EAGLView.mm" because it's a "library file". 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; And in this context, it is very very very common to see programmers lazily type cast the. Infact I know several systems where that does not hold. ../lib/odp-util.c:5601:9: note: expanded from macro 'SCAN_PUT' void* -> integer -> void* rather than integer -> void* -> integer. From that point on, you are dealing with 32 bits. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. ^~~~~~~~~~~~~~~~~~~ How can this new ban on drag possibly be considered constitutional? 471,961 Members | 900 Online. As Ferruccio said, int must be replaced with intptr_t to make the program meaningful. 1. You may declare a const int variable and cast its reference to the void*. Identify those arcade games from a 1983 Brazilian music video. I have a two functions, one that returns an int, and one that takes a const void* as an argument. How to get the error message from the error code returned by GetLastError()? 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.

cast to void *' from smaller integer type 'int 2023