/** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. [Solved] Error "Cast from pointer to smaller type 'int' | 9to5Answer Sign in If you cast an int pointer int, you might get back a different integer. SCAN_PUT_ATTR(key, ATTR, skey, FUNC); But assuming that it is, as long as the caller and the callee agree, you can do that sort of thing. Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin?). That could create all kinds of trouble. rev2023.3.3.43278. error: cast from pointer to smaller type 'unsigned int' loses information. Taking the above declarations of A, D, ch of the . 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. [Solved] Properly casting a `void*` to an integer in C++ Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? 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). Why do academics stay as adjuncts for years rather than move around? 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. If the destination type is bool, this is a boolean conversion (see below). 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. As was pointed out by Martin, this presumes that sizeof(void*)>=sizeof(int). Thanks for contributing an answer to Stack Overflow! how to cascade 2d int array to 2d void pointer array? 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 Is it possible to create a concave light? You should perform type conversion based on 64bit build system because the type "int" supports only -32768 ~ 32768. Error while setting app icon and launch image in xcode 5.1. @Shahbaz you could but I will not suggest to a C newbie to use globals. 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: ids [i] = (int) (size_t)touch; : iPhone Retina 4-inch 64-bit) is selected. 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. and how to print the thread id of 2d array argument? 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. I wish that you write those answer first than the explanation. I'm trying to learn pthreads and thing that keeps bugging me is how do i really pass argument to the function. 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]. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? How to use Slater Type Orbitals as a basis functions in matrix method correctly? This will get you a pointer from a 32 bit offset: A function pointer is incompatible to void* (and any other non function pointer). Star 675. whether it was an actual problem is a different matter though. Basically its a better version of (void *)i. 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. Issues. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Can we typecast void into int? - Quora Why did Ukraine abstain from the UNHRC vote on China? In my case, I was using a 32-bit value that needed to be passed to an OpenGL function as a void * representing an offset into a buffer. How to make compiler not show int to void pointer cast warnings, incompatible pointer types assigning to 'void (*)(void *)' from 'int (int *)'. So make sure you understand what you are doing! Surely the solution is to change the type of ids from int to type that is sufficiently large to hold a pointer. 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! Connect and share knowledge within a single location that is structured and easy to search. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' C / C++ Forums on Bytes. 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. But, sure, in that specific case you can pass a local variable address, type casting integer to void* [duplicate]. Therefore it is perfectly valid for the compiler to throw an error for a line like. rev2023.3.3.43278. 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. C/C++ , Cerror: cast to 'void *' from smaller integer type 'int'. What is "cast from integer to pointer of different size" warning? For integer casts in specific, using into() signals that . Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin? Casting type void to uint8_t - Arduino Forum Floating-point conversions Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, @Dinesh: could you please 1) show us those. Cast unsigned char (uint8 *) pointer to unsigned long (uint32 *) pointer 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. BUT converting a pointer to void* and back again is well supported (everywhere). 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. Making statements based on opinion; back them up with references or personal experience. GitHub. 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; Recovering from a blunder I made while emailing a professor. LLNL's tutorial is bad and they should feel bad. Press question mark to learn the rest of the keyboard shortcuts. Identify those arcade games from a 1983 Brazilian music video. What does it mean to convert int to void* or vice versa? Put your define inside a bracket: without a problem. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Half your pointer will be garbage. A nit: in your version, the cast to void * is unnecessary. reinterpret_cast conversion - cppreference.com casting from int to void* and back to int. Is it possible to create a concave light? Do new devs get fired if they can't solve a certain bug? Update: Today, i download the latest version of cocos2d-x (cocos2d-x 2.2.3). SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); 4. Type Conversions - C in a Nutshell [Book] - O'Reilly Online Learning That's probably going to be true for most platforms you will ever encounter, but it's not a guarantee; it's implementation-dependent. Using Kolmogorov complexity to measure difficulty of problems? Use of Void pointers in C programming language Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. actually no, as int my be a smaller type than a pointer ;-) But, of course with int64_t it works fine. Asking for help, clarification, or responding to other answers. Already on GitHub? Can I tell police to wait and call a lawyer when served with a search warrant? Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. what does it mean to convert int to void* or vice versa? INT36-C. Converting a pointer to integer or integer to pointer 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. SCAN_PUT_ATTR(mask, ATTR, smask, FUNC); How do I work around the GCC "error: cast from SourceLocation* to int loses precision" error when compiling cmockery.c? 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. Actions. So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. Create an account to follow your favorite communities and start taking part in conversations. 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. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? 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. How to get the error message from the error code returned by GetLastError()? vegan) just to try it, does this inconvenience the caterers and staff? On most platforms pointers and longs are the same size, but ints and pointers often are not the same size on 64bit platforms. Implicit Type Conversion is also known as 'automatic type conversion'. Yeah, the tutorial is doing it wrong. Yeah, the tutorial is doing it wrong. Converting one datatype into another is known as type casting or, type-conversion. Why is there a voltage on my HDMI and coaxial cables? Your first example is risky because you have to be very careful about the object lifetimes. c - type casting integer to void* - Stack Overflow If you write ((char*)ptr + 1), it will advance the pointer 1 byte, because a "char" is 1 byte. To perform a cast, specify the type that you are casting to in parentheses in front of the value or variable to be converted. How do I align things in the following tabular environment? You are correct, but cocos actually only uses that address as a unique id. Can anybody explain how to pass an integer to a function which receives (void * ) as a parameter? You can use any other pointer, or you can use (size_t), which is 64 bits. Remembering to delete the pointer after use so that we don't leak. eg. But then you need to cast your arguments inside your thread function which is quite unsafe cf. The subreddit for the C programming language, Press J to jump to the feed. And in this context, it is very very very common to see programmers lazily type cast the. Thanks for pointing that out. Using indicator constraint with two variables. Remarks. use $(ARCHS_STANDARD_32_BIT) at Architecture instead of $(ARCHS_STANDARD). 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). Is pthread_join a must when using pthread in linux? How to use Slater Type Orbitals as a basis functions in matrix method correctly? 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. However the actual code in question contains an explicit c-style cast to int. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? Thank you all for your feedback. To learn more, see our tips on writing great answers. The preprocesor absolutely will not perform arithmetic. Connect and share knowledge within a single location that is structured and easy to search. Even though what you say regarding the lifetime of the object is true, integral types are too limited for a generic API. How to correctly cast a pointer to int in a 64-bit application? 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. (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. Note:You might receive a runtime exception if the pointer contains a value unsuitable for the context. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Type conversions - cplusplus.com Well it does this because you are converting a 64 bits pointer to an 32 bits integer so you loose information. How do I set, clear, and toggle a single bit? 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. Connect and share knowledge within a single location that is structured and easy to search. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. You may declare a const int variable and cast its reference to the void*. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Setting a buffer of char* with intermediate casting to int*. B programing language is a language based on basic combined programming or a BCPL, and it is the precursor of the C programming language. It was derived from the BCPL, and the name of the b language is possibly from the BCPL contraction. then converted back to pointer to void, and the result will compare what does it mean to convert int to void* or vice versa? Unless you have a valid address at that value, you are going to invoke undefined behaviour when try to use that pointer. "After the incident", I started to be more careful not to trip over things. 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 Therefore, you need to change it to long long instead of long in windows for 64 bits. "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. I am an entry level C programmer. this way you won't get any warning. Since all pointers on 64-bit Windows are 64 bits, you are growing the data size from 32 bits backto 64 bits. This method will not work on 64 bit Big Endian platform, so it unnecessarily breaks portability. rev2023.3.3.43278. A void pointer can be really useful if the programmer is not sure about the data type of data inputted by the end user. Typically, long or unsigned long is . All float types are to be converted to double. How to correctly cast a pointer to int in a 64-bit application? Casting a pointer to void* and back is valid use of reinterpret_cast<>. error: cast from 'void*' to 'int' loses precision - Stack Overflow The only alternative is really to take time and fix all 64-bit code issues, of which there may be some non-trivial issues. The result is the same as implicit conversion from the enum's underlying type to the destination type. Functions return bigint only if the parameter expression is a bigint data type. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. @Artelius: Which, presumably, is exactly what Joshua did: A C++ reinterpret cast will not solve the problem. 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. 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. What video game is Charlie playing in Poker Face S01E07? Pull requests. INT31-C. Ensure that integer conversions do not result in lost or You can convert the values from one type to another explicitly using the cast operator as follows (type_name) expression cast to void *' from smaller integer type 'int Does a summoned creature play immediately after being summoned by a ready action? If you are going to pass the address you typically need to exert some more control over the lifetime of the object. I usually have all automatic conversion warnings effective when developing in C, and I use explicit casting in order to suppress a specific . 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.. Is a PhD visitor considered as a visiting scholar. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? If you call your thread creation function like this, then the void* arriving inside of myFcn has the value of the int you put into it. Type casting is when you assign a value of one primitive data type to another type. So,solution #3 works just fine. Apparently the clang version in Xcode 5.1 and above is more strict about potential 32bit vs. 64 bit incompatibilities in source code than older clang versions have been. Whats the grammar of "For those whose stories they are"? There's no proper way to cast this to int in general case. What does casting to void* does when passing arguments to variadic functions? Bulk update symbol size units from mm to map units in rule-based symbology. SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. Java Type Casting - W3Schools In Java, there are two types of casting: Widening Casting (automatically) - converting a smaller type to a larger type size. There exist two main syntaxes for generic type-casting: functional and c-like: 1 2 3 4 double x = 10.3; int y; y = int (x); // functional notation y = (int) x; // c-like cast notation The functionality of these generic forms of type-casting is enough for most needs with fundamental data types. To be honest, I think, clang is too restrictive here. Asking for help, clarification, or responding to other answers. C99 defines the types "intptr_t" and "uintptr_t" which do . By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. long guarantees a pointer size on Linux on any machine. Any help with this is appreciated. Java Type Casting (With Examples) - Programiz this way I convert an int to a void* which is much better than converting a void* to an int. If you preorder a special airline meal (e.g. In the case of Widening Type Casting, the lower data type (having smaller size) is converted into the higher data type (having larger size). Implicit conversions - cppreference.com What is the point of Thrower's Bandolier? How to Cast a void* ponter to a char without a warning? Connect and share knowledge within a single location that is structured and easy to search. I have looked around and can't seem to find any information on how to do this. This page has been accessed 1,655,678 times. Why is this sentence from The Great Gatsby grammatical? To avoid truncating your pointer, cast it to a type of identical size. // OK: lvalue denoting the original d object, // UB: the b subobject is not a base class subobject, // 6. array-to-pointer followed by upcast, https://en.cppreference.com/mwiki/index.php?title=cpp/language/static_cast&oldid=147983, when converting a 'pointer to object' to 'pointer to, the conversion from floating-point values, the conversion from bit-fields to rvalue references, the conversion from integral or enumeration values to enumeration, the conversion from integral or enumeration values to, the conversion from a member of base class type to, a standard-layout class object with no data members, a non-standard-layout union object and a non-static data, for base-to-derived pointer conversions and, the conversion to enumeration types with fixed underlying type, a standard-layout class might have a non-pointer-interconvertible, If the underlying type is not fixed, the behavior is undefined if the value of, If the underlying type is fixed, the result is the same as, one is a union object and the other is a non-static data member of that object, or. 10) A prvalue of type pointer to void (possibly cv-qualified) can be converted to pointer to any object type. Why does Mister Mxyzptlk need to have a weakness in the comics? And when assigning to a void pointer, all type information is lost. 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)). Share Improve this answer Follow answered May 6, 2018 at 7:24 Rahul This answer is incorrect for the reasons that have already been mentioned in the comment of, Error "Cast from pointer to smaller type 'int' loses information" in EAGLView.mm when update Xcode to 5.1 (5B130a), http://en.wikipedia.org/wiki/64-bit_computing#64-bit_data_models, http://stackoverflow.com/questions/18913906/xcode-5-and-ios-7-architecture-and-valid-architectures, How Intuit democratizes AI development across teams through reusability. ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] I guess the other important fact is that the cast operator has higher precedence that the multiplication operator. "-D_FILE_OFFSET_BITS=64" "-Wall" "-Winvalid-pch" "-g" "-Wthread-safety" "-Wno-microsoft-enum-forward-reference" "-Wno-unused-function" "-Wno-sometimes-unini How to correctly cast a pointer to int in a 64-bit application? Here is my code: I already tried (void*)M_TABLE_SIZE but then I get an error that I cannot use the * operator. You could use this code, and it would do the same thing as casting ptr to (char*). A cast specifies a conversion from one type to another. Bulk update symbol size units from mm to map units in rule-based symbology. FAILED: lib/libopenvswitch.a.p/odp-util.c.obj That's not a good idea if the original object (that was cast to void*) was an integer. The reinterpret_cast makes the int the size of a pointer and the warning will stop. All character types are to be converted to an integer. Find centralized, trusted content and collaborate around the technologies you use most. Replacing broken pins/legs on a DIP IC package, AC Op-amp integrator with DC Gain Control in LTspice. reinterpret_cast<void *>(42)). casting from int to void* and back to int - C / C++ What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? 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. ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' To learn more, see our tips on writing great answers. ../lib/odp-util.c:5603:13: note: expanded from macro 'SCAN_PUT' Terrible solution. 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. The problem is not with casting, but with the target type loosing half of the pointer. It is commonly called a pointer to T and its type is T*. Replacing broken pins/legs on a DIP IC package, How to handle a hobby that makes income in US. pthread passes the argument as a void*. this way you won't get any warning. Don't do that. What is the difference between const int*, const int * const, and int const *? ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] ^~~~~~~~~~~~~~~~~~~~~ Noncompliant Code Example (memset())For historical reasons, certain C Standard functions accept an argument of type int and convert it to either unsigned char or plain char. 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 ) XCode 5.1 is change all architecture to 64 bit. (int) pthread_self() 64int48intuintptr_t (unsigned int) If the value is ever used as pointer again that will prove to be an extremely bad idea. I think the solution 3> should be the correct one. Have a question about this project? Well occasionally send you account related emails. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. In the best case this will give the same results as the original code, with no advantages, but in the worst case it will fail in multiple catastrophic ways (type punning, endianness, less efficient, etc. "I think what you should do is actually pass the address of the variable to the function" Not necessarily. So you know you can cast it back like this. You can fix this error by replacing this line of code. Does melting sea ices rises global sea level? On all of them int is 32bit, not 16bit. rev2023.3.3.43278. Don't do that. 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.

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