cast to void *' from smaller integer type 'int

FAILED: lib/libopenvswitch.a.p/odp-util.c.obj to the original pointer: The following type designates an unsigned integer type with the The compiler issues the "cast from integer to pointer of different size" warning whenever the value of an integer is converted to a pointer, especially when the memory allocated to a pointer is smaller than the memory allocated to an integer data type. Using indicator constraint with two variables. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. A cast converts an object or value from one type to another. The subreddit for the C programming language, Press J to jump to the feed. STR34-C. Losing bytes like thisis called 'truncation', and that's what the first warning is telling you. How Intuit democratizes AI development across teams through reusability. So,solution #3 works just fine. The text was updated successfully, but these errors were encountered: You signed in with another tab or window. Why did Ukraine abstain from the UNHRC vote on China? 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. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? then converted back to pointer to void, and the result will compare to your account, [87/252] Compiling C object lib/libopenvswitch.a.p/odp-util.c.obj Don't do that. The calculated expression consists of two operations. 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. reinterpret_cast is a type of casting operator used in C++. How do I check if a string represents a number (float or int)? Connect and share knowledge within a single location that is structured and easy to search. "-D_FILE_OFFSET_BITS=64" "-Wall" "-Winvalid-pch" "-g" "-Wthread-safety" "-Wno-microsoft-enum-forward-reference" "-Wno-unused-function" "-Wno-sometimes-unini Use #include to define it. ^~~~~~~~~~~~~~~~~~~~ tialized" "-Wno-format" "-Wno-incompatible-pointer-types" "-Werror" "-dM" "-U_MSC_VER" "-D_TIMESPEC_DEFINED" "-D_CRT_NONSTDC_NO_DEPRECATE -D_CRT_SECURE_NO_WA Note the difference between the type casting of a variable and type casting of a pointer. How can this new ban on drag possibly be considered constitutional? Where does this (supposedly) Gibson quote come from? (void *)i Error: cast to 'void *' from smaller integer type 'int'. I have the following function and when I compile it under VS.NET 2005, the following compile warnings show up: Warning1warning C4311: 'type cast' : pointer truncation from 'void *' to 'long'c:\temp\testone\lib\utils.c56Warning2warning C4312: 'type cast' : conversion from 'unsigned long' to 'void *' of greater sizec:\temp\testone\lib\utils.c56, Code Snippet How to use Slater Type Orbitals as a basis functions in matrix method correctly? This is a fine way to pass integers to new pthreads, if that is what you need. The only alternative is really to take time and fix all 64-bit code issues, of which there may be some non-trivial issues. Create an account to follow your favorite communities and start taking part in conversations. ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Making statements based on opinion; back them up with references or personal experience. "clang" "-Ilib\libopenvswitch.a.p" "-Ilib" "-I..\lib" "-I." What you do here is undefined behavior, and undefined behavior of very practical sort. There's no proper way to cast this to int in general case. windows meson: cast to smaller integer type 'unsigned long' from 'void *'. Can I tell police to wait and call a lawyer when served with a search warrant? Does Counterspell prevent from any further spells being cast on a given turn? In both cases, converting the pointer to an integer type that's too small to represent all pointer values is a bug. The problem just occur with Xcode 5.1. However even though their types are different, the address is going to be the same. 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. This is known as implicit type casting or type promotion, compiler automatically converts smaller data type to larger data type. For a fairly recent compiler (that supports C99) you should not store or represent address as plain int value. Safe downcast may be done with dynamic_cast. Why does flowing off the end of a non-void function without returning a value not produce a compiler error? "-I.." "-Iinclude\openflow" "-I..\include\openflow" "-Iinclude\openvswitch" "-I..\include\openvsw 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. @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. 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. Connect and share knowledge within a single location that is structured and easy to search. Pd = Pa; Similarly, Pc may be type cast to type int and assigned the value Pa. 1. I am an entry level C programmer. 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. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? this way you won't get any warning. On all of them int is 32bit, not 16bit. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. If you preorder a special airline meal (e.g. Since all pointers on 64-bit Windows are 64 bits, you are growing the data size from 32 bits backto 64 bits. If your code has the chance to ever be ported to some platform where this doesn't hold, this won't work. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? The dynamic_cast<>operator provides a way to check the actual type of a pointer to a polymorphic class. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Acidity of alcohols and basicity of amines. SCAN_PUT_ATTR(key, ATTR, skey, FUNC); Surely the solution is to change the type of ids from int to type that is sufficiently large to hold a pointer. What is the point of Thrower's Bandolier? The value of float variable is= 37.75. We have to pass address of the variable to the function because in function definition argument is pointer variable. 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). If your standard library (even if it is not C99) happens to provide these types - use them. Identify those arcade games from a 1983 Brazilian music video, Relation between transaction data and transaction id, The difference between the phonemes /p/ and /b/ in Japanese. Error while setting app icon and launch image in xcode 5.1. I get the error: "cast to smaller integer type 'int' from 'string' (aka 'char *')" referencing line of code: while (isalpha(residents[i].name) == 0), How Intuit democratizes AI development across teams through reusability. The correct answer is, if one does not mind losing data precision. I am compiling this program in linux gcc compiler.. Before I update Xcode, my project still can build and run normally with all devices. When is casting void pointer needed in C? 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. But I'm nitpicking .. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, "what happen when typcating normal variable to void* or any pointer variable?" 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. Do new devs get fired if they can't solve a certain bug? Bulk update symbol size units from mm to map units in rule-based symbology. As was pointed out by Martin, this presumes that sizeof(void*)>=sizeof(int). rev2023.3.3.43278. The result is implementation-defined and typically yields the numeric address of the byte in memory that the pointer pointers to. But assuming that it is, as long as the caller and the callee agree, you can do that sort of thing. Thanks for pointing that out. // 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. The result is the same as implicit conversion from the enum's underlying type to the destination type. Such a downcast makes no runtime checks to ensure that the object's runtime type is actually D, and may only be used safely if this precondition is guaranteed by other means, such as when implementing static polymorphism. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. what does it mean to convert int to void* or vice versa? Does a summoned creature play immediately after being summoned by a ready action? That's probably going to be true for most platforms you will ever encounter, but it's not a guarantee; it's implementation-dependent. Put your define inside a bracket: without a problem. 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. Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin?). 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. 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). Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Notifications. Can I tell police to wait and call a lawyer when served with a search warrant? @DietrichEpp can you explain what is race condition with using. What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. (int) pthread_self() 64int48intuintptr_t (unsigned int) The best way is, if one can, do not do such casting, instead, if the same memory address has to be shared for pointer and int (e.g. Disconnect between goals and daily tasksIs it me, or the industry? Does Counterspell prevent from any further spells being cast on a given turn? The main point is: a pointer has a platform dependent size. I usually have all automatic conversion warnings effective when developing in C, and I use explicit casting in order to suppress a specific . On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin? 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. If pointers are 64 bits and ints are 32 bits, an int is too small to hold a pointer value. 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. C/C++ , Cerror: cast to 'void *' from smaller integer type 'int'. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. casting from int to void* and back to int. Can Martian regolith be easily melted with microwaves? 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. 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. And, most of these will not even work on gcc4. Why is there a voltage on my HDMI and coaxial cables? 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. byte -> short -> char -> int -> long -> float -> double. Taking the above declarations of A, D, ch of the . An open (void) pointer can hold a pointer of any type. privacy statement. The reinterpret_cast makes the int the size of a pointer and the warning will stop. 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. 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. This page has been accessed 1,655,678 times. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. If your standard library (even if it is not C99) happens to provide these types - use them. Yeah, the tutorial is doing it wrong. XCode 5.1 is change all architecture to 64 bit. All float types are to be converted to double. 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". But gcc always give me a warning, that i cannot cast an int to a void*. 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. A cast specifies a conversion from one type to another. rev2023.3.3.43278. So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. By clicking Sign up for GitHub, you agree to our terms of service and I don't see how anything bad can happen . "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. 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]. How create a simple program using threads in C? Functions return bigint only if the parameter expression is a bigint data type. If this is the data to a thread procedure, then you quite commonly want to pass by value. @Artelius: Which, presumably, is exactly what Joshua did: A C++ reinterpret cast will not solve the problem. what does it mean to convert int to void* or vice versa? Next, when doing pointer arithmetic, the addition operation will use the pointer's type to determine how many bytes to add to it when incrementing it. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. I'm trying to create a void* from an int. 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. For example, if you want to store a 'long' value into a simple integer then you can type cast 'long' to 'int'. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? return ((void **) returnPtr);} /* Matrix() */. Did i have to face to unexpected runtime issues, i guess not, i've found another discussion on this -. 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). A missing cast in the new fast > enumeration code. It's an int type guaranteed to be big enough to contain a pointer. Mutually exclusive execution using std::atomic? rev2023.3.3.43278. The program can be set in such a way to ask the user to inform the type of data and . The int data type is the primary integer data type in SQL Server. ^~~~~~~~~~~~~~~~~~~~ 10) A prvalue of type pointer to void (possibly cv-qualified) can be converted to pointer to any object type. As a result of the integer division 3/2 we get the value 1, which is of the int type. And when assigning to a void pointer, all type information is lost. Remembering to delete the pointer after use so that we don't leak. 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. In Java, there are two types of casting: Widening Casting (automatically) - converting a smaller type to a larger type size. How do I count the number of sentences in C using ". error: comparison between pointer and integer ('int' and 'string' (aka 'char *')), CS50 Caesar program is working but check50 says it isn't. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? 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]. } SCAN_END_SINGLE(ATTR) A nit: in your version, the cast to void * is unnecessary. The difference between a and &a is the type. @jackdoe: It's a waste of human life to write code that "you may need in the future". I assumed that gcc makes a 65536 out of my define, but I was wrong. with ids being an array of ints and touch being a pointer. Bulk update symbol size units from mm to map units in rule-based symbology. Alternatively, if you choose to castthe ptr variableto (size_t) instead, then you don't need to worry about the pointer typeanymore. But this code pass the normal variable .. Java Type Casting. Most answers just try to extract 32 useless bits out of the argument. Using Kolmogorov complexity to measure difficulty of problems? Sign up for a free GitHub account to open an issue and contact its maintainers and the community. 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. Disconnect between goals and daily tasksIs it me, or the industry? How do I align things in the following tabular environment? However, you are also casting the result of this operation to (void*). It is purely a compile-time directive which instructs the compiler to treat expression as if it had . Actions. The text was updated successfully, but these errors were encountered: Why is this sentence from The Great Gatsby grammatical? Pull requests. Why does setupterm terminate the program? If not, check the pointer size on your platform, define these typedefs accordingly yourself and use them. Don't do that. 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 To be honest, I think, clang is too restrictive here. Getting Command /bin/sh failed with exit code 65 Error with Xcode 5.1 . Fork 63. should we also have a diagnostic for the (presumed) user error? 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.. No sense in writing a few dozen lines of extra code just to get a bunch of numbered threads. Therefore, you need to change it to long long instead of long in windows for 64 bits. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. Note:You might receive a runtime exception if the pointer contains a value unsuitable for the context. equal to the original pointer: First you are using a define, which is not a variable. 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). Thanks for contributing an answer to Stack Overflow! property that any valid pointer to void can be converted to this type, Yeah, the tutorial is doing it wrong. Find centralized, trusted content and collaborate around the technologies you use most. 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). If int is no larger than pointer to void then one way to store the value is by simply copying the bytes: int i . Remarks. Based on the design of this function, which modification is right. SCAN_PUT_ATTR(mask, ATTR, smask, FUNC); Then i can continue compiling. Visit Microsoft Q&A to post new questions. For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, error: cast from void* to int loses precision, cast to pointer from integer of different size, pthread code. 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. a cast of which the programmer should be aware of what (s)he is doing. It is done by the compiler on its own, without any external trigger from the user. An object pointer (including void*) or function pointer can be converted to an integer type using reinterpret_cast. To learn more, see our tips on writing great answers. 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). The most general answer is - in no way. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. How to make compiler not show int to void pointer cast warnings, incompatible pointer types assigning to 'void (*)(void *)' from 'int (int *)'. It generally takes place when in an expression more than one data type is present. If the function had the correct signature you would not need to cast it explicitly.

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