How to correctly cast a pointer to int in a 64-bit application? From that point on, you are dealing with 32 bits. LLNL's tutorial is bad and they should feel bad. How to correctly cast a pointer to int in a 64-bit application? 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. To learn more, see our tips on writing great answers. Unless you have a valid address at that value, you are going to invoke undefined behaviour when try to use that pointer. Why do small African island nations perform better than African continental nations, considering democracy and human development? If this is the data to a thread procedure, then you quite commonly want to pass by value. ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' A nit: in your version, the cast to void * is unnecessary. a cast of which the programmer should be aware of what (s)he is doing. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Does Counterspell prevent from any further spells being cast on a given turn? Before I update Xcode, my project still can build and run normally with all devices. Yeah, the tutorial is doing it wrong. Please unaccept the answer you have chosen as it is wrong (as the comments below it say) and will lead to bugs. I need to convert the argument to an int for later use: The compiler (GCC version 4.2.4) returns the error: You can cast it to an intptr_t type. What is the point of Thrower's Bandolier? Disconnect between goals and daily tasksIs it me, or the industry? What does it mean to convert int to void* or vice versa? Why is this sentence from The Great Gatsby grammatical? Using Kolmogorov complexity to measure difficulty of problems? This will only compile if the destination type is long enough. Converting a pointer to an integer whose result cannot represented in the integer type is undefined behavior is C and prohibited in C++. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. ", "? Are there tables of wastage rates for different fruit and veg? 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. In such a case the programmer can use a void pointer to point to the location of the unknown data type. You think by casting it here that you are avoiding the problem! The cast back to int * is not, though. The correct answer is, if one does not mind losing data precision. Why does Mister Mxyzptlk need to have a weakness in the comics? Cerror: cast to 'void *' from smaller integer type 'int' By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Is it possible to create a concave light? what happens when we typecast normal variable to void* or any pointer variable? It solved my problem too. ), For those who are interested. vegan) just to try it, does this inconvenience the caterers and staff? Does melting sea ices rises global sea level? But then you need to cast your arguments inside your thread function which is quite unsafe cf. 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. this question. 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. To avoid truncating your pointer, cast it to a type of identical size. The following behavior-changing defect reports were applied retroactively to previously published C++ standards. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? This page was last modified on 12 February 2023, at 18:25. Thanks for contributing an answer to Stack Overflow! STR34-C. Asking for help, clarification, or responding to other answers. Can I tell police to wait and call a lawyer when served with a search warrant? GitHub. But I'm nitpicking .. How to make compiler not show int to void pointer cast warnings, incompatible pointer types assigning to 'void (*)(void *)' from 'int (int *)'. Pd = Pa; Similarly, Pc may be type cast to type int and assigned the value Pa. 1. And in this context, it is very very very common to see programmers lazily type cast the. byte -> short -> char -> int -> long -> float -> double. You are just making it bigger by tricking the compiler and the ABI. Find centralized, trusted content and collaborate around the technologies you use most. How Intuit democratizes AI development across teams through reusability. for saving RAM), use union, and make sure, if the mem address is treated as an int only if you know it was last set as an int. You can convert the values from one type to another explicitly using the cast operator as follows (type_name) expression Sign in even though the compiler doesn't know you only ever pass myFcn to pthread_create in conjunction with an integer. If you do this, you have the thread reference a value that (hopefully still) lives in some other thread. 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. Click to see the query in the CodeQL repository. So,solution #3 works just fine. error: comparison between pointer and integer ('int' and 'string' (aka 'char *')), CS50 Caesar program is working but check50 says it isn't. 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.. p-util.c.obj "-c" ../lib/odp-util.c ^~~~~~~~~~~~~~~~~~~~ How can this new ban on drag possibly be considered constitutional? @DavidHeffernan I rephrased that sentence a little. It's always a good practice to put your #define's in brackets to avoid such surprise. c - type casting integer to void* - Stack Overflow All float types are to be converted to double. There's no proper way to cast this to int in general case. Java Type Casting - W3Schools The int data type is the primary integer data type in SQL Server. Why does flowing off the end of a non-void function without returning a value not produce a compiler error? 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. Press question mark to learn the rest of the keyboard shortcuts. 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. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? I assumed that gcc makes a 65536 out of my define, but I was wrong. rev2023.3.3.43278. If you preorder a special airline meal (e.g. and how to print the thread id of 2d array argument? Returns a value of type new-type. You can only do this if you use a synchronization primitive to ensure that there is no race condition. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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. Here, the Java first converts the int type data into the double type. pthread passes the argument as a void*. The difference between the phonemes /p/ and /b/ in Japanese, Styling contours by colour and by line thickness in QGIS. If you are going to pass the address you typically need to exert some more control over the lifetime of the object. Acidity of alcohols and basicity of amines. FAILED: lib/libopenvswitch.a.p/odp-util.c.obj AC Op-amp integrator with DC Gain Control in LTspice. The result is implementation-defined and typically yields the numeric address of the byte in memory that the pointer pointers to. 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 How to notate a grace note at the start of a bar with lilypond? vegan) just to try it, does this inconvenience the caterers and staff? 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). static_cast conversion - cppreference.com If the value is ever used as pointer again that will prove to be an extremely bad idea. Thank you all for your feedback. Or, they are all wrong. Implementation-dependent. returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size); No idea how it amassed 27 upvotes?! Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. He should pass the address of the integer, the thread should get that address, Note: This is only appropriate is you cast the. c - Cast int to void* - Stack Overflow Difficulties with estimation of epsilon-delta limit proof. 4. Type Conversions - C in a Nutshell [Book] - O'Reilly Online Learning 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 subreddit for the C programming language, Press J to jump to the feed. If any, how can the original function works without errors if we just ignore the warning. 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; This is not a conversion at all. casting from int to void* and back to int - C / C++ How to use Slater Type Orbitals as a basis functions in matrix method correctly? ^~~~~~~~~~~~~~~~~~~~~ Fix for objc/45925 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. All character types are to be converted to an integer. But gcc always give me a warning, that i cannot cast an int to a void*. What is the correct method to cast an int to a void*? Connect and share knowledge within a single location that is structured and easy to search. Update: Today, i download the latest version of cocos2d-x (cocos2d-x 2.2.3). that any valid pointer to void can be converted to this type, then By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Java Type Casting. Create an account to follow your favorite communities and start taking part in conversations. The preprocessor will replace your code by this: This is unlikely what you are trying to do. This is a fine way to pass integers to new pthreads, if that is what you need. Implicit conversions - cppreference.com C / C++ Forums on Bytes. Actions. But the problem has still happened. C99 defines the types "intptr_t" and "uintptr_t" which do . If you preorder a special airline meal (e.g. For example, if you want to store a 'long' value into a simple integer then you can type cast 'long' to 'int'. @Martin York: No, it doesn't depend on endiannness. *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 . The only exception is exotic systems with the SILP64 data model, where the size of int is also 64 bits. long guarantees a pointer size on Linux on any machine. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. what does it mean to convert int to void* or vice versa? Type casting is when you assign a value of one primitive data type to another type. If int is no larger than pointer to void then one way to store the value is by simply copying the bytes: int i . The main point is: a pointer has a platform dependent 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. 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. Find centralized, trusted content and collaborate around the technologies you use most. 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. Mutually exclusive execution using std::atomic? That could create all kinds of trouble. The proper way is to cast it to another pointer type. Such pointers can be stored in 32-bit data types (for instance, int, DWORD). It is done by the compiler on its own, without any external trigger from the user. STR34-C. Cast characters to unsigned char before converting to larger To be honest, I think, clang is too restrictive here. int, bigint, smallint, and tinyint (Transact-SQL) - SQL Server 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. */ >> -bool >> +enum conversion_safety >> unsafe_conversion_p (tree type, tree expr, bool . Asking for help, clarification, or responding to other answers. C/C++ , Cerror: cast to 'void *' from smaller integer type 'int'. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? Find centralized, trusted content and collaborate around the technologies you use most. It is easier to understand and write than any other assembly language. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. You could use this code, and it would do the same thing as casting ptr to (char*). Casting int to void* : r/C_Programming - reddit 471,961 Members | 900 Online. Note:You might receive a runtime exception if the pointer contains a value unsuitable for the context. You may declare a const int variable and cast its reference to the void*. property that any valid pointer to void can be converted to this type, How to use Slater Type Orbitals as a basis functions in matrix method correctly? Does ZnSO4 + H2 at high pressure reverses to Zn + H2SO4? 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. sound/soc/codecs/tlv320aic32x4.c:1202:18: warning: cast to smaller windows meson: cast to 'HANDLE' (aka 'void *') from smaller 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). 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. How to get the error message from the error code returned by GetLastError()? Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin?). The reinterpret_cast makes the int the size of a pointer and the warning will stop. Why did Ukraine abstain from the UNHRC vote on China? 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. If your standard library (even if it is not C99) happens to provide these types - use them. 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. The following program casts a double to an int. However the actual code in question contains an explicit c-style cast to int. 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. My code is all over the place now but I appreciate you all helping me on my journey to mastery! 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]. Bulk update symbol size units from mm to map units in rule-based symbology. Not the answer you're looking for? Bulk update symbol size units from mm to map units in rule-based symbology. Share Improve this answer Follow answered May 6, 2018 at 7:24 Rahul Making statements based on opinion; back them up with references or personal experience. SCAN_PUT_ATTR(mask, ATTR, smask, FUNC); It's an int type guaranteed to be big enough to contain a pointer. Can I tell police to wait and call a lawyer when served with a search warrant? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Your first example is risky because you have to be very careful about the object lifetimes. There is no "correct" way to store a 64-bit pointer in an 32-bit integer. ), Styling contours by colour and by line thickness in QGIS. Example: int x=7, y=5; float z; z=x/y; /*Here the value of z is 1*/. For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Use returnPtr[j] = (void *) ((long)ptr + i); ). You can fix this error by replacing this line of code. 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". 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 10) A prvalue of type pointer to void (possibly cv-qualified) can be converted to pointer to any object type. INT31-C. Ensure that integer conversions do not result in lost or Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, @Dinesh: could you please 1) show us those. linux c-pthreads: problem with local variables. For example, the main thread could wait for all of the other threads to end before terminating. How do I count the number of sentences in C using ". 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! If you cast an int pointer int, you might get back a different integer. XCode 5.1 is change all architecture to 64 bit. [Solved] Properly casting a `void*` to an integer in C++ Typecasting - Data Types - Language Basics - MQL4 Reference SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); Cast Operations - Oracle reinterpret_cast<void *>(42)). "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. 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). Casting Pointers - IBM Why do academics stay as adjuncts for years rather than move around? then converted back to pointer to void, and the result will compare Put your define inside a bracket: without a problem. 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 Does Counterspell prevent from any further spells being cast on a given turn? 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. Don't do that. clang warnings in v1.42 Issue #265 ocornut/imgui GitHub SCAN_PUT_ATTR(key, ATTR, skey, FUNC); 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. How do I align things in the following tabular environment? Keep in mind that thrArg should exist till the myFcn() uses it. : iPhone Retina 4-inch 64-bit) is selected. While working with Threads in C, I'm facing the warning, "warning: cast to pointer from integer of different size". -1, Uggh. [that could be a TODO - not to delay solving the ICE].