I assumed that gcc makes a 65536 out of my define, but I was wrong. What is the correct method to cast an int to a void*? vegan) just to try it, does this inconvenience the caterers and staff? } SCAN_END_SINGLE(ATTR) 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". Once you manage to make this cast, then what?! By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 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 may declare a const int variable and cast its reference to the void*. Connect and share knowledge within a single location that is structured and easy to search. 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. 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. SCAN_PUT_ATTR(mask, ATTR, smask, FUNC); C++ Tutorial => Conversion between pointer and integer Not the answer you're looking for? The result is the same as implicit conversion from the enum's underlying type to the destination type. Properly casting a `void*` to an integer in C++ 24,193 Solution 1 I think using intptr_t is the correct intermediate here, since it's guaranteed to be large enough to contain the integral value of the void*, and once I have an integer value I can then truncate it without causing the compiler to complain. If you really need such trickery, then consider one of dedicated types, which are intptr_t and uintptr_t. Passing arguments to pthread_create - invalid conversion from void(*)() to void(*)(void*). Update: Today, i download the latest version of cocos2d-x (cocos2d-x 2.2.3). Casting type int to const void* - C / C++ Sign up for a free GitHub account to open an issue and contact its maintainers and the community. Anw, the project still build and run normally when i use Xcode 5.0 with iOS 7.0. ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Converting a void* to an int is non-portable way that may work or may not! Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. Casting type void to uint8_t - Arduino Forum 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. Where does this (supposedly) Gibson quote come from? You think by casting it here that you are avoiding the problem! For a fairly recent compiler (that supports C99) you should not store or represent address as plain int value. That's not a good idea if the original object (that was cast to void*) was an integer. So,solution #3 works just fine. Casting arguments inside the function is a lot safer. Disconnect between goals and daily tasksIs it me, or the industry? Click to see the query in the CodeQL repository. Connect and share knowledge within a single location that is structured and easy to search. You can convert the values from one type to another explicitly using the cast operator as follows (type_name) expression . Well occasionally send you account related emails. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. : iPhone Retina 4-inch 64-bit) is selected. Can I tell police to wait and call a lawyer when served with a search warrant? Connect and share knowledge within a single location that is structured and easy to search. Any expression can be cast to type void (which means that the result of the expression is ignored), but it's not legal to cast an expression of type void to type int not least because the result of such a cast wouldn't make any sense. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. reinterpret_cast<void *>(42)). what happens when we typecast normal variable to void* or any pointer variable? This allows you to reinterpret the void * as an int. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. what does it mean to convert int to void* or vice versa? Therefore, you need to change it to long long instead of long in windows for 64 bits. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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. Type casting is when you assign a value of one primitive data type to another type. Before I update Xcode, my project still can build and run normally with all devices. 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 That's probably going to be true for most platforms you will ever encounter, but it's not a guarantee; it's implementation-dependent. The high-order 9 bits of the number are used to hold a flag value, and the result is converted back into a pointer. 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. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? 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. How do I set, clear, and toggle a single bit? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. If you cast an int pointer int, you might get back a different integer. A nit: in your version, the cast to void * is unnecessary. Mutually exclusive execution using std::atomic? lexborisov Modest Public. The text was updated successfully, but these errors were encountered: So you know you can cast it back like this. 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;. [mst-vhost:vhost 5/52] drivers/block/virtio_blk.c:539:21: warning ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] Asking for help, clarification, or responding to other answers. Remembering to delete the pointer after use so that we don't leak. 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. I am compiling this program in linux gcc compiler.. If your standard library (even if it is not C99) happens to provide these types - use them. It was derived from the BCPL, and the name of the b language is possibly from the BCPL contraction. 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. Alternatively, if you choose to castthe ptr variableto (size_t) instead, then you don't need to worry about the pointer typeanymore. 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. [] ExplanatioUnlike static_cast, but like const_cast, the reinterpret_cast expression does not compile to any CPU instructions (except when converting between integers and pointers or on obscure architectures where pointer representation depends on its type). Asking for help, clarification, or responding to other answers. How to get the error message from the error code returned by GetLastError()? This is what the second warning is telling you. The preprocesor absolutely will not perform arithmetic. C++ how to get the address stored in a void pointer? Asking for help, clarification, or responding to other answers. Are there tables of wastage rates for different fruit and veg? 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. If any, how can the original function works without errors if we just ignore the warning. Your first example is risky because you have to be very careful about the object lifetimes. Asking for help, clarification, or responding to other answers. Find centralized, trusted content and collaborate around the technologies you use most. 10) A prvalue of type pointer to void (possibly cv-qualified) can be converted to pointer to any object type. On all of them int is 32bit, not 16bit. actually no, as int my be a smaller type than a pointer ;-) But, of course with int64_t it works fine. If you do this, you have the thread reference a value that (hopefully still) lives in some other thread. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? 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. Unless you have a valid address at that value, you are going to invoke undefined behaviour when try to use that pointer. Floating-point conversions Cast unsigned char (uint8 *) pointer to unsigned long (uint32 *) pointer Replacing broken pins/legs on a DIP IC package, How to handle a hobby that makes income in US. However the actual code in question contains an explicit c-style cast to int. What is the point of Thrower's Bandolier? Press question mark to learn the rest of the keyboard shortcuts. Narrowing Casting (manually) - converting a larger type to a . There's no proper way to cast this to int in general case. There is absolutely not gurantee that sizeof(int) <= sizeof(void*). You are just making it bigger by tricking the compiler and the ABI. When is casting void pointer needed in C? Converting one datatype into another is known as type casting or, type-conversion. a cast of which the programmer should be aware of what (s)he is doing. If your code has the chance to ever be ported to some platform where this doesn't hold, this won't work. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Did i have to face to unexpected runtime issues, i guess not, i've found another discussion on this -. Usually that means the pointer is allocated with. windows meson: cast to smaller integer type 'unsigned long' from 'void *'. Offline ImPer Westermark over 11 years ago in reply to Andy Neil Except that you sometimes stores an integer in the pointer itself. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. Hence there is no loss in data. You are correct, but cocos actually only uses that address as a unique id. In the case of Widening Type Casting, the lower data type (having smaller size) is converted into the higher data type (having larger size). Put your define inside a bracket: without a problem. In such a case the programmer can use a void pointer to point to the location of the unknown data type. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? Does Counterspell prevent from any further spells being cast on a given turn? You could use this code, and it would do the same thing as casting ptr to (char*). equal to the original pointer: First you are using a define, which is not a variable. Getting Command /bin/sh failed with exit code 65 Error 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. What does casting to void* does when passing arguments to variadic functions? 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. 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. Find centralized, trusted content and collaborate around the technologies you use most. rev2023.3.3.43278. How do I check if a string represents a number (float or int)? Acidity of alcohols and basicity of amines. 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. 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. -1, Uggh. Yeah, the tutorial is doing it wrong. INT36-C. Converting a pointer to integer or integer to pointer B Programming Language | What is the History and Concept? Or, they are all wrong. that any valid pointer to void can be converted to this type, then this way you won't get any warning. 4. Type Conversions - C in a Nutshell [Book] - O'Reilly Online Learning What does it mean to convert int to void* or vice versa? rev2023.3.3.43278. Disconnect between goals and daily tasksIs it me, or the industry? How to use Slater Type Orbitals as a basis functions in matrix method correctly? 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 Using indicator constraint with two variables. The only alternative is really to take time and fix all 64-bit code issues, of which there may be some non-trivial issues. Please unaccept the answer you have chosen as it is wrong (as the comments below it say) and will lead to bugs. 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. ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' "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. 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.. I'm using cocos2d-x-2.2.2. You use the address-of operator & to do that. This is not a conversion at all. Half your pointer will be garbage. What is "cast from integer to pointer of different size" warning? p-util.c.obj "-c" ../lib/odp-util.c Why is there a voltage on my HDMI and coaxial cables? Thanks for contributing an answer to Stack Overflow! The problem just occur with Xcode 5.1. this way you won't get any warning. The difference between the phonemes /p/ and /b/ in Japanese, Styling contours by colour and by line thickness in QGIS. ", "? 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. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? vegan) just to try it, does this inconvenience the caterers and staff? There's probably little you can do except look or hope for a fixed 2.x version or upgrade to 3.x (I would assume it's 64-bit safe but this is just a guess, do research this issue before you upgrade). 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. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 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. 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. Create an account to follow your favorite communities and start taking part in conversations. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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 ^~~~~~~~~~~~~~~~~~~ But the problem has still happened. I have a two functions, one that returns an int, and one that takes a const void* as an argument. rev2023.3.3.43278. 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 But assuming that it is, as long as the caller and the callee agree, you can do that sort of thing. For example, if you want to store a 'long' value into a simple integer then you can type cast 'long' to 'int'. to your account, [87/252] Compiling C object lib/libopenvswitch.a.p/odp-util.c.obj To learn more, see our tips on writing great answers. If pointers are 64 bits and ints are 32 bits, an int is too small to hold a pointer value. How can this new ban on drag possibly be considered constitutional? */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j; The dynamic_cast<>operator provides a way to check the actual type of a pointer to a polymorphic class. I cannot reverse my upvote of user384706's answer, but it's wrong. For example, the main thread could wait for all of the other threads to end before terminating. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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. Projects. How do I force make/GCC to show me the commands? However, I believe that even if the define was for the "65536", it would not be what @kaetzacoatl wanted. GitHub. Whats the grammar of "For those whose stories they are"? You are getting warnings due to casting a void* to a type of a different size. Thanks for contributing an answer to Stack Overflow! sound/soc/codecs/tlv320aic32x4.c:1202:18: warning: cast to smaller You need to pass an actual pointer. Otherwise, if the original pointer value points to an object a, and there is an object b of the . The point is (probably) that the value passed to the thread is an integer value, not really a 'void *'. 471,961 Members | 900 Online. Asking for help, clarification, or responding to other answers. What is the purpose of non-series Shimano components? 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. pthread passes the argument as a void*. I think the solution 3> should be the correct one. Implementing From will result in the Into implementation but not vice-versa. Converting a pointer to an integer whose result cannot represented in the integer type is undefined behavior is C and prohibited in C++. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. "clang" "-Ilib\libopenvswitch.a.p" "-Ilib" "-I..\lib" "-I." Implicit conversions - cppreference.com long guarantees a pointer size on Linux on any machine. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? Is it possible to create a concave light? I usually have all automatic conversion warnings effective when developing in C, and I use explicit casting in order to suppress a specific . Making statements based on opinion; back them up with references or personal experience. In such condition type conversion (type promotion) takes place to avoid loss of data. 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. Difficulties with estimation of epsilon-delta limit proof. Even though what you say regarding the lifetime of the object is true, integral types are too limited for a generic API. What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 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. AC Op-amp integrator with DC Gain Control in LTspice. ../lib/odp-util.c:5603:13: note: expanded from macro 'SCAN_PUT' @kshegunov said in Number Type Cast: const void * x; int y = int (x); compiles just fine. Only the following conversions can be done with static_cast, except when such conversions would cast away constness or volatility. Implementation-dependent. How do I count the number of sentences in C using ". The 32 remaining bits stored inside int are insufficient to reconstruct a pointer to the thread function. // 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. Functions return bigint only if the parameter expression is a bigint data type. use $(ARCHS_STANDARD_32_BIT) at Architecture instead of $(ARCHS_STANDARD).
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