cast to void *' from smaller integer type 'int10 marca 2023
Can anybody explain how to pass an integer to a function which receives (void * ) as a parameter? 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). If you write ((char*)ptr + 1), it will advance the pointer 1 byte, because a "char" is 1 byte. reinterpret_cast<void *>(42)). windows meson: cast to smaller integer type 'unsigned long' from 'void *'. For example, the main thread could wait for all of the other threads to end before terminating. The text was updated successfully, but these errors were encountered: You signed in with another tab or window. Taking the above declarations of A, D, ch of the . To access the object value, use the * dereference operator: int * p; assert (p == null ); p = new int (5); assert (p != null ); assert (*p == 5); (*p)++; assert (*p == 6); If a pointer contains a null value, it is not pointing to a valid object. rev2023.3.3.43278. Java Type Casting. But I'm nitpicking .. you can just change architecture to support 32 bit compilation by all below in in Build Settings. error: cast from pointer to smaller type 'unsigned int' loses information. Since all pointers on 64-bit Windows are 64 bits, you are growing the data size from 32 bits backto 64 bits. Please help me compile Chez Scheme. 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.. While working with Threads in C, I'm facing the warning, "warning: cast to pointer from integer of different size". Here is my code: I already tried (void*)M_TABLE_SIZE but then I get an error that I cannot use the * operator. If your standard library (even if it is not C99) happens to provide these types - use them. I'm unfamiliar with XCode, but the solution should be something like follows: Most of the "solutions" above can lose part of the pointer address when casting to a smaller type. My code is all over the place now but I appreciate you all helping me on my journey to mastery! 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. This is not even remotely "the correct answer". Offline ImPer Westermark over 11 years ago in reply to Andy Neil Except that you sometimes stores an integer in the pointer itself. Connect and share knowledge within a single location that is structured and easy to search. 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. SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); This is not a conversion at all. 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. Thanks for contributing an answer to Stack Overflow! and how to print the thread id of 2d array argument? I assumed that gcc makes a 65536 out of my define, but I was wrong. SCAN_PUT_ATTR(key, ATTR, skey, FUNC); If you preorder a special airline meal (e.g. 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. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Making statements based on opinion; back them up with references or personal experience. "clang" "-Ilib\libopenvswitch.a.p" "-Ilib" "-I..\lib" "-I." The result is implementation-defined and typically yields the numeric address of the byte in memory that the pointer pointers to. Why does flowing off the end of a non-void function without returning a value not produce a compiler error? How do I align things in the following tabular environment? 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. The difference between the phonemes /p/ and /b/ in Japanese, Styling contours by colour and by line thickness in QGIS. 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; There's no proper way to cast this to int in general case. then converted back to pointer to void, and the result will compare This allows you to reinterpret the void * as an int. For a fairly recent compiler (that supports C99) you should not store or represent address as plain int value. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? ../lib/odp-util.c:5601:9: note: expanded from macro 'SCAN_PUT' You can fix this error by replacing this line of code. How Intuit democratizes AI development across teams through reusability. All float types are to be converted to double. If your code has the chance to ever be ported to some platform where this doesn't hold, this won't work. GitHub. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? How do I force make/GCC to show me the commands? ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. 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 C99 defines the types "intptr_t" and "uintptr_t" which do . Can I tell police to wait and call a lawyer when served with a search warrant? But assuming that it is, as long as the caller and the callee agree, you can do that sort of thing. Find centralized, trusted content and collaborate around the technologies you use most. The problem just occur with Xcode 5.1. 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. Unless you have a valid address at that value, you are going to invoke undefined behaviour when try to use that pointer. "I think what you should do is actually pass the address of the variable to the function" Not necessarily. XCode 5.1 is change all architecture to 64 bit. 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 ", "!"? In the first example, the variable c1 of the char type is converted to a temporary variable of the int type, because the second operand in the division operation, the constant 2, is of the higher type int. Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin?). I'm new to coding and am trying to implement a simple program on my own, that prompts the user the number of residents in an apt complex, the prompts the user to enter the names and apt numbers of each resident. Based on the design of this function, which modification is right. 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)). ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' 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. As was pointed out by Martin, this presumes that sizeof(void*)>=sizeof(int). Converts between types using a combination of implicit and user-defined conversions. Only the following conversions can be done with static_cast, except when such conversions would cast away constness or volatility. 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. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Therefore it is perfectly valid for the compiler to throw an error for a line like. 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. (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. 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 Keep in mind that thrArg should exist till the myFcn() uses it. You may declare a const int variable and cast its reference to the void*. this way I convert an int to a void* which is much better than converting a void* to an int. Does ZnSO4 + H2 at high pressure reverses to Zn + H2SO4? how to cascade 2d int array to 2d void pointer array? casting from int to void* and back to int. I'm trying to create a void* from an int. Infact I know several systems where that does not hold. Don't do that. Recovering from a blunder I made while emailing a professor. to your account, [87/252] Compiling C object lib/libopenvswitch.a.p/odp-util.c.obj Issues. 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). LLNL's tutorial is bad and they should feel bad. If the function had the correct signature you would not need to cast it explicitly. 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 forum has migrated to Microsoft Q&A. void* -> integer -> void* rather than integer -> void* -> integer. Projects. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. rev2023.3.3.43278. The point is (probably) that the value passed to the thread is an integer value, not really a 'void *'. returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size); 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. You are getting warnings due to casting a void* to a type of a different size. If this is the data to a thread procedure, then you quite commonly want to pass by value. Did i have to face to unexpected runtime issues, i guess not, i've found another discussion on this -. 1. If int is no larger than pointer to void then one way to store the value is by simply copying the bytes: int i . This solution is in accordance with INT18-C. How to correctly cast a pointer to int in a 64-bit application? I have looked around and can't seem to find any information on how to do this. Asking for help, clarification, or responding to other answers. 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; I have a two functions, one that returns an int, and one that takes a const void* as an argument. */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j; The value of float variable is= 37.75. Whats the grammar of "For those whose stories they are"? How do I count the number of sentences in C using ". 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 this question. ^~~~~~~~~~~~~~~~~~~~ There are ways to prevent this: pass a dynamic allocated argument if your not the passing thread is not static or if your argument is a local variable, otherwise there is no issue. SCAN_PUT(ATTR, NULL); Safe downcast may be done with dynamic_cast. *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 . 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). error: comparison between pointer and integer ('int' and 'string' (aka 'char *')), CS50 Caesar program is working but check50 says it isn't. Basically its a better version of (void *)i. 7.1 New Cast Operations The C++ standard defines new cast operations that provide finer control than previous cast operations. What video game is Charlie playing in Poker Face S01E07? This is known as implicit type casting or type promotion, compiler automatically converts smaller data type to larger data type. This is why you got Error 1 C2036, from your post. For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. itch" "-I..\include\windows" "-Iinclude" "-I..\include" "-I..\datapath-windows\include" "-IC:\PTHREADS-BUILT\include" "-Xclang" "-fcolor-diagnostics" "-pipe" Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Setting a buffer of char* with intermediate casting to int*. SCAN_PUT_ATTR(mask, ATTR, smask, FUNC); 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. Remarks. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. This is a fine way to pass integers to new pthreads, if that is what you need. Why is this sentence from The Great Gatsby grammatical? If the value in a pointer is cast to a different type and it does not have the correct alignment for the new type, the behavior is undefined. A nit: in your version, the cast to void * is unnecessary. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. ../lib/odp-util.c:5603:13: note: expanded from macro 'SCAN_PUT' @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. 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. What does casting to void* does when passing arguments to variadic functions? 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