cast to void *' from smaller integer type 'int

Does a summoned creature play immediately after being summoned by a ready action? To perform a cast, specify the type that you are casting to in parentheses in front of the value or variable to be converted. 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. How to correctly cast a pointer to int in a 64-bit application? Connect and share knowledge within a single location that is structured and easy to search. 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. this way you won't get any warning. Replacing broken pins/legs on a DIP IC package, AC Op-amp integrator with DC Gain Control in LTspice. I am an entry level C programmer. A cast converts an object or value from one type to another. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? How Intuit democratizes AI development across teams through reusability. Please unaccept the answer you have chosen as it is wrong (as the comments below it say) and will lead to bugs. Maybe you can try this too. } SCAN_END_SINGLE(ATTR) Notifications. You need to pass an actual pointer. Find centralized, trusted content and collaborate around the technologies you use most. 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). But I don't want to edit code in "EAGLView.mm" because it's a "library file". If the original pointer value represents an address of a byte in memory that does not satisfy the alignment requirement of the target type, then the resulting pointer value is unspecified. Bulk update symbol size units from mm to map units in rule-based symbology. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. I have a two functions, one that returns an int, and one that takes a const void* as an argument. Note the difference between the type casting of a variable and type casting of a pointer. Thanks for contributing an answer to Stack Overflow! Making statements based on opinion; back them up with references or personal experience. A pointer converted to an integer of sufficient size and back to the same pointer type is guaranteed to have its original value, otherwise the resulting pointer cannot be dereferenced safely ( the round-trip conversion in the opposite direction is not guaranteed [.]) Where does this (supposedly) Gibson quote come from? Issues. how to cascade 2d int array to 2d void pointer array? How to use Slater Type Orbitals as a basis functions in matrix method correctly? /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. This forum has migrated to Microsoft Q&A. So make sure you understand what you are doing! I assumed that gcc makes a 65536 out of my define, but I was wrong. You are just making it bigger by tricking the compiler and the ABI. Use returnPtr[j] = (void *) ((long)ptr + i); ). C / C++ Forums on Bytes. that any valid pointer to void can be converted to this type, then What is the difference between const int*, const int * const, and int const *? "clang" "-Ilib\libopenvswitch.a.p" "-Ilib" "-I..\lib" "-I." 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: ids [i] = (int) (size_t)touch; The difference between the phonemes /p/ and /b/ in Japanese. From that point on, you are dealing with 32 bits. This is known as implicit type casting or type promotion, compiler automatically converts smaller data type to larger data type. In both cases, converting the pointer to an integer type that's too small to represent all pointer values is a bug. From what I read about casting in the C11 standard, my feeling is, that it is arguable to emit a warning on an explicit conversion. Converting a pointer to an integer whose result cannot represented in the integer type is undefined behavior is C and prohibited in C++. 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;. To learn more, see our tips on writing great answers. Safe downcast may be done with dynamic_cast. Put your define inside a bracket: without a problem. clang11 report error: cast to smaller integer type #82 - GitHub p-util.c.obj "-c" ../lib/odp-util.c 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. actually no, as int my be a smaller type than a pointer ;-) But, of course with int64_t it works fine. How do I set, clear, and toggle a single bit? If you are going to pass the address you typically need to exert some more control over the lifetime of the object. And when assigning to a void pointer, all type information is lost. 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. Not the answer you're looking for? void* to an array - C++ Forum - cplusplus.com So reinterpret_cast has casted it to long type and then static_cast safely casts long to int, if you are ready do truncte the data. // 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. 4. Type Conversions - C in a Nutshell [Book] - O'Reilly Online Learning 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. rev2023.3.3.43278. rev2023.3.3.43278. Yeah, the tutorial is doing it wrong. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? Instead of using a long cast, you should cast to size_t. Netdev Archive on lore.kernel.org help / color / mirror / Atom feed * [mst-vhost:vhost 5/52] drivers/block/virtio_blk.c:539:21: warning: assignment to 'void *' from . If you really need such trickery, then consider one of dedicated types, which are intptr_t and uintptr_t. */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j; 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; equal to the original pointer: First you are using a define, which is not a variable. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. In the case of Widening Type Casting, the lower data type (having smaller size) is converted into the higher data type (having larger size). 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. Type conversions - cplusplus.com 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. int, bigint, smallint, and tinyint (Transact-SQL) - SQL Server Why does Mister Mxyzptlk need to have a weakness in the comics? It is commonly called a pointer to T and its type is T*. I usually have all automatic conversion warnings effective when developing in C, and I use explicit casting in order to suppress a specific . 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. XCode 5.1 is change all architecture to 64 bit. This page was last modified on 12 February 2023, at 18:25. 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 A nit: in your version, the cast to void * is unnecessary. 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. Apparently the clang version in Xcode 5.1 and above is more strict about potential 32bit vs. 64 bit incompatibilities in source code than older clang versions have been. LLNL's tutorial is bad and they should feel bad. Can anybody explain how to pass an integer to a function which receives (void * ) as a parameter? How to correctly cast a pointer to int in a 64-bit application? 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. Sign in Here is my code: I already tried (void*)M_TABLE_SIZE but then I get an error that I cannot use the * operator. this question. GitHub. ^~~~~~~~~~~~~~~~~~~~~ Since gcc compiles that you are performing arithmetic between void* and an int (1024). ../lib/odp-util.c:5489:33: note: expanded from macro 'SCAN_PUT_ATTR' eg. 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. @Martin York: No, it doesn't depend on endiannness. Find centralized, trusted content and collaborate around the technologies you use most. Where does this (supposedly) Gibson quote come from? Number Type Cast | Qt Forum Passing arguments to pthread_create - invalid conversion from void(*)() to void(*)(void*). Find centralized, trusted content and collaborate around the technologies you use most. 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! From the question I presume the OP does. 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 preprocessor will replace your code by this: This is unlikely what you are trying to do. If int is no larger than pointer to void then one way to store the value is by simply copying the bytes: int i . @LearnCocos2D: so, how can i "overcome" the error without editing any not-my-code or in-library-file lines? AC Op-amp integrator with DC Gain Control in LTspice. As Ferruccio said, int must be replaced with intptr_t to make the program meaningful. . INT36-C. Converting a pointer to integer or integer to pointer error: cast from pointer to smaller type 'unsigned int' loses information. If you need to keep the returned address, just keep it as void*. ../lib/odp-util.c:5603:13: note: expanded from macro 'SCAN_PUT' You are getting warnings due to casting a void* to a type of a different size. Example: int x=7, y=5; float z; z=x/y; /*Here the value of z is 1*/. C - Type Casting - tutorialspoint.com SQL Server does not automatically promote . @kshegunov said in Number Type Cast: const void * x; int y = int (x); compiles just fine. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Can I tell police to wait and call a lawyer when served with a search warrant? Why does setupterm terminate the program? The code ((void*)ptr + 1) does not work, because the compiler has no idea what size "void" is, and therefore doesn't know how many bytes to add. Most answers just try to extract 32 useless bits out of the argument. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. But I'm nitpicking .. Is it possible to create a concave light? byte -> short -> char -> int -> long -> float -> double. @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. [Solved] Error "Cast from pointer to smaller type 'int' | 9to5Answer 471,961 Members | 900 Online. should we also have a diagnostic for the (presumed) user error? 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. As a result of the integer division 3/2 we get the value 1, which is of the int type. property that any valid pointer to void can be converted to this type, Pull requests. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. ERROR: incompatible integer to pointer conversion assigning to 'string' (aka 'char *') from 'int', error: cast to 'string' (aka 'char *') from smaller integer type 'int' [-Werror,-Wint-to-pointer-cast], error: incompatible integer to pointer conversion assigning to 'string' (aka 'char *') from 'int' C, warning: initialization of 'unsigned char' from 'uint8_t *' {aka 'unsigned char *'} makes integer from pointer without a cast [-Wint-conversion], Minimising the environmental effects of my dyson brain. Click to see the query in the CodeQL repository. For example, the main thread could wait for all of the other threads to end before terminating. Please tell me error: cast from 'void*' to 'int' loses precision, How Intuit democratizes AI development across teams through reusability. This will only compile if the destination type is long enough. Casting arguments inside the function is a lot safer. The difference between the phonemes /p/ and /b/ in Japanese, Styling contours by colour and by line thickness in QGIS. The high-order 9 bits of the number are used to hold a flag value, and the result is converted back into a pointer. Therefore, you need to change it to long long instead of long in windows for 64 bits. long guarantees a pointer size on Linux on any machine. I'm trying to create a void* from an int. The proper way is to cast it to another pointer type. ), For those who are interested. 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. 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. Anw, the project still build and run normally when i use Xcode 5.0 with iOS 7.0. (void *)i Error: cast to 'void *' from smaller integer type 'int'. If the value is ever used as pointer again that will prove to be an extremely bad idea. The 32 remaining bits stored inside int are insufficient to reconstruct a pointer to the thread function. This method will not work on 64 bit Big Endian platform, so it unnecessarily breaks portability. Why did Ukraine abstain from the UNHRC vote on China? cast to 'void *' from smaller integer type 'int' pthread passes the argument as a void*. 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. You are right! . Windows has 32 bit long only on 64 bit as well. Making statements based on opinion; back them up with references or personal experience. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? 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: ids [i] = (int) (size_t)touch; If pointers are 64 bits and ints are 32 bits, an int is too small to hold a pointer value. You should perform type conversion based on 64bit build system because the type "int" supports only -32768 ~ 32768. rev2023.3.3.43278. Why does flowing off the end of a non-void function without returning a value not produce a compiler error? How to get the error message from the error code returned by GetLastError()? ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Based on the design of this function, which modification is right. SCAN_PUT(ATTR, NULL); whether it was an actual problem is a different matter though. rev2023.3.3.43278. You think by casting it here that you are avoiding the problem! How can this new ban on drag possibly be considered constitutional? Typically, long or unsigned long is . Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? c - type casting integer to void* - Stack Overflow ^~~~~~~~~~~~~~~~~~~ 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. Is it possible to create a concave light? arrays - I get the error: "cast to smaller integer type 'int' from to the original pointer: The following type designates an unsigned integer type with the C++ Tutorial => Conversion between pointer and integer Yeah, the tutorial is doing it wrong. [that could be a TODO - not to delay solving the ICE]. ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' In C (int)b is called an explicit conversion, i.e. sound/soc/codecs/tlv320aic32x4.c:1202:18: warning: cast to smaller Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. This is an old C callback mechanism so you can't change that. 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. Recovering from a blunder I made while emailing a professor. I'm only guessing here, but I think what you are supposed to do is actually pass the address of the variable to the function. That's not a good idea if the original object (that was cast to void*) was an integer. But gcc always give me a warning, that i cannot cast an int to a void*. Well occasionally send you account related emails. c - How to cast an integer to void pointer? - Stack Overflow Press question mark to learn the rest of the keyboard shortcuts. Replacing broken pins/legs on a DIP IC package, How to handle a hobby that makes income in US. Note that it's not guaranteed that casting an, Generally this kind of type casting does not lead to any concern as long as the addresses are encoded using the same length as the "variable type" (. Since all pointers on 64-bit Windows are 64 bits, you are growing the data size from 32 bits backto 64 bits. ), Styling contours by colour and by line thickness in QGIS. (i.e. 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. 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. Type Casting Of Pointers in C - Computer Notes Actions. windows meson: cast to 'HANDLE' (aka 'void *') from smaller integer Compile error on Android ARM Issue #163 cisco/ChezScheme

Who Lives On The Biltmore Estate Today, Michelle Steel Net Worth, Articles C