This is why you got Error 1 C2036, from your post. 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. pthread passes the argument as a void*. But this code pass the normal variable .. 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 to convert a factor to integer\numeric without loss of information? A cast converts an object or value from one type to another. - the incident has nothing to do with me; can I use this this way? I'm using cocos2d-x-2.2.2. 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? It is easier to understand and write than any other assembly language. Please tell me error: cast from 'void*' to 'int' loses precision, How Intuit democratizes AI development across teams through reusability. Example: int x=7, y=5; float z; z=x/y; /*Here the value of z is 1*/. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' Can anybody explain how to pass an integer to a function which receives (void * ) as a parameter? Otherwise, if the original pointer value points to an object a, and there is an object b of the . Linear regulator thermal information missing in datasheet. Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin?). On all of them int is 32bit, not 16bit. Acidity of alcohols and basicity of amines. The difference between the phonemes /p/ and /b/ in Japanese, Styling contours by colour and by line thickness in QGIS. A void pointer can be really useful if the programmer is not sure about the data type of data inputted by the end user. 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. How create a simple program using threads in C? 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. 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 correct answer is, if one does not mind losing data precision. Based on the design of this function, which modification is right. A cast specifies a conversion from one type to another. Mutually exclusive execution using std::atomic? 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. rev2023.3.3.43278. In a 64bit build a pointer is 64bit (contrary to a 32bit build, where it is 32bit), while an int is 32bit, so this assignment stores a 64bit value in a 32bit storage, which may result in a loss of information. 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. ../lib/odp-util.c:5489:33: note: expanded from macro 'SCAN_PUT_ATTR' 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. Why is this sentence from The Great Gatsby grammatical? Maybe you can try this too. what does it mean to convert int to void* or vice versa? rev2023.3.3.43278. And you can't pass a pointer to a stack based object from the other thread as it may no longer be valid. Offline ImPer Westermark over 11 years ago in reply to Andy Neil Except that you sometimes stores an integer in the pointer itself. : iPhone Retina 4-inch 64-bit) is selected. 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. Usually that means the pointer is allocated with. Use returnPtr[j] = (void *) ((long)ptr + i); ). 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; } SCAN_END_SINGLE(ATTR) 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). Or, they are all wrong. 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. I have a function with prototype void* myFcn(void* arg) which is used as the starting point for a pthread. No sense in writing a few dozen lines of extra code just to get a bunch of numbered threads. Is a PhD visitor considered as a visiting scholar. However even though their types are different, the address is going to be the same. ../lib/odp-util.c:5601:9: note: expanded from macro 'SCAN_PUT' The text was updated successfully, but these errors were encountered: This example is noncompliant on an implementation where pointers are 64 bits and unsigned integers are 32 bits because the result of converting the 64-bit ptr cannot be represented in the 32-bit integer type. All character types are to be converted to an integer. 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). *PATCH] platform/x86: hp-wmi: Fix cast to smaller integer type warning @ 2023-01-23 13:28 Hans de Goede 2023-01-23 13:56 ` Hans de Goede 0 siblings, 1 reply; 2+ messages in thread From: Hans de Goede @ 2023-01-23 13:28 UTC (permalink / raw) To: Mark Gross Cc: Hans de Goede, Andy Shevchenko, platform-driver-x86, kernel test robot Fix the following . If you write ((char*)ptr + 1), it will advance the pointer 1 byte, because a "char" is 1 byte. 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. If the destination type is bool, this is a boolean conversion (see below). Implementation-dependent. Just edited. This solution is in accordance with INT18-C. 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. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Can I tell police to wait and call a lawyer when served with a search warrant? However the actual code in question contains an explicit c-style cast to int. rev2023.3.3.43278. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. When is casting void pointer needed in C? A nit: in your version, the cast to void * is unnecessary. byte -> short -> char -> int -> long -> float -> double. Bulk update symbol size units from mm to map units in rule-based symbology. SCAN_PUT(ATTR, NULL); You are just making it bigger by tricking the compiler and the ABI. You can use any other pointer, or you can use (size_t), which is 64 bits. How do I set, clear, and toggle a single bit? Surely the solution is to change the type of ids from int to type that is sufficiently large to hold a pointer. There's no proper way to cast this to int in general case. 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;. void* -> integer -> void* rather than integer -> void* -> integer. Visit Microsoft Q&A to post new questions. But assuming that it is, as long as the caller and the callee agree, you can do that sort of thing. What is the purpose of non-series Shimano components? Do new devs get fired if they can't solve a certain bug? 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. This is memory reinterpretation - a completely unacceptable way to do what the OP is trying to do. Typically, long or unsigned long is . "After the incident", I started to be more careful not to trip over things. Using Kolmogorov complexity to measure difficulty of problems? that any valid pointer to void can be converted to this type, then Does Counterspell prevent from any further spells being cast on a given turn? The program can be set in such a way to ask the user to inform the type of data and . Bulk update symbol size units from mm to map units in rule-based symbology. @LearnCocos2D: so, how can i "overcome" the error without editing any not-my-code or in-library-file lines? You are right! 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 Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, @Dinesh: could you please 1) show us those. As was pointed out by Martin, this presumes that sizeof(void*)>=sizeof(int). Thanks for contributing an answer to Stack Overflow! But the problem has still happened. And when assigning to a void pointer, all type information is lost. The preprocessor will replace your code by this: This is unlikely what you are trying to do. It generally takes place when in an expression more than one data type is present. Hence there is no loss in data. This page has been accessed 1,655,678 times. But gcc always give me a warning, that i cannot cast an int to a void*. Thanks Jonathan, I was thinking about my answer in another thread: AraK is correct, passing integers a pointers are not necessarily interchangeable. Type casting is when you assign a value of one primitive data type to another type. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? Basically its a better version of (void *)i. And, most of these will not even work on gcc4. Floating-point conversions reinterpret_cast<void *>(42)). This is a fine way to pass integers to new pthreads, if that is what you need. B language was designed to develop . Asking for help, clarification, or responding to other answers. To learn more, see our tips on writing great answers. Returns a value of type new-type. There is absolutely not gurantee that sizeof(int) <= sizeof(void*). Find centralized, trusted content and collaborate around the technologies you use most. 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). The proper way is to cast it to another pointer type. The problem just occur with Xcode 5.1. It is done by the compiler on its own, without any external trigger from the user. Why is there a voltage on my HDMI and coaxial cables? The following behavior-changing defect reports were applied retroactively to previously published C++ standards. However, I believe that even if the define was for the "65536", it would not be what @kaetzacoatl wanted. @jackdoe: It's a waste of human life to write code that "you may need in the future". Notifications. Before I update Xcode, my project still can build and run normally with all devices. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 10) A prvalue of type pointer to void (possibly cv-qualified) can be converted to pointer to any object type. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? Connect and share knowledge within a single location that is structured and easy to search. What you do here is undefined behavior, and undefined behavior of very practical sort. Replacing broken pins/legs on a DIP IC package, How to handle a hobby that makes income in US. Can I tell police to wait and call a lawyer when served with a search warrant? What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? vegan) just to try it, does this inconvenience the caterers and staff? In the case of Widening Type Casting, the lower data type (having smaller size) is converted into the higher data type (having larger size). I guess the other important fact is that the cast operator has higher precedence that the multiplication operator. A nit: in your version, the cast to void * is unnecessary. Now, what happens when I run it with the thread sanitizer? If your code has the chance to ever be ported to some platform where this doesn't hold, this won't work. Here, the Java first converts the int type data into the double type. Did i have to face to unexpected runtime issues, i guess not, i've found another discussion on this -. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Narrowing Casting (manually) - converting a larger type to a . ^~~~~~~~~~~~~~~~~~~~~ LLNL's tutorial is bad and they should feel bad. You can convert the values from one type to another explicitly using the cast operator as follows (type_name) expression Don't do that. @Artelius: Which, presumably, is exactly what Joshua did: A C++ reinterpret cast will not solve the problem. */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j; I need to cast the int from the first function so that I can use it as an argument for the second function. Here is my code: I already tried (void*)M_TABLE_SIZE but then I get an error that I cannot use the * operator. 7.1 New Cast Operations The C++ standard defines new cast operations that provide finer control than previous cast operations. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? The result is implementation-defined and typically yields the numeric address of the byte in memory that the pointer pointers to. 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. The main point is: a pointer has a platform dependent size. How can this new ban on drag possibly be considered constitutional? Projects. The only alternative is really to take time and fix all 64-bit code issues, of which there may be some non-trivial issues. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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. Windows has 32 bit long only on 64 bit as well. How to tell which packages are held back due to phased updates, Identify those arcade games from a 1983 Brazilian music video. Since gcc compiles that you are performing arithmetic between void* and an int (1024). Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? However, you are also casting the result of this operation to (void*). A missing cast in the new fast > enumeration code. 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 (void *)i Error: cast to 'void *' from smaller integer type 'int'. If you really need such trickery, then consider one of dedicated types, which are intptr_t and uintptr_t. If pointers are 64 bits and ints are 32 bits, an int is too small to hold a pointer value. Can Martian regolith be easily melted with microwaves? Is pthread_join a must when using pthread in linux? /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. Asking for help, clarification, or responding to other answers. FAILED: lib/libopenvswitch.a.p/odp-util.c.obj We have to pass address of the variable to the function because in function definition argument is pointer variable. ^~~~~~~~~~~~~~~~~~~~ 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;. The following program casts a double to an int. Most answers just try to extract 32 useless bits out of the argument. 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. Bulk update symbol size units from mm to map units in rule-based symbology. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. I usually have all automatic conversion warnings effective when developing in C, and I use explicit casting in order to suppress a specific . What video game is Charlie playing in Poker Face S01E07? 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. Terrible solution. How to use Slater Type Orbitals as a basis functions in matrix method correctly? @kshegunov said in Number Type Cast: const void * x; int y = int (x); compiles just fine. 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. For a fairly recent compiler (that supports C99) you should not store or represent address as plain int value. Why does flowing off the end of a non-void function without returning a value not produce a compiler error? Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Setting a buffer of char* with intermediate casting to int*. 1. ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' @BlueMoon Thanks a lot! p-util.c.obj "-c" ../lib/odp-util.c 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. Your first example is risky because you have to be very careful about the object lifetimes. "-D_FILE_OFFSET_BITS=64" "-Wall" "-Winvalid-pch" "-g" "-Wthread-safety" "-Wno-microsoft-enum-forward-reference" "-Wno-unused-function" "-Wno-sometimes-unini for (i=0, j=0; j

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