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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. 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. You need to pass an actual pointer. And when assigning to a void pointer, all type information is lost. 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. Surely the solution is to change the type of ids from int to type that is sufficiently large to hold a pointer. However the actual code in question contains an explicit c-style cast to int. 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. 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. 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 difference between a and &a is the type. And you can't pass a pointer to a stack based object from the other thread as it may no longer be valid. to the original pointer: The following type designates an unsigned integer type with the 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. 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. Converting a pointer to an integer whose result cannot represented in the integer type is undefined behavior is C and prohibited in C++. Converting one datatype into another is known as type casting or, type-conversion. 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). Is a PhD visitor considered as a visiting scholar. Can Martian regolith be easily melted with microwaves? The proper way is to cast it to another pointer type. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? 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). even though the compiler doesn't know you only ever pass myFcn to pthread_create in conjunction with an integer. ^~~~~~~~~~~~~~~~~~~~ I guess the other important fact is that the cast operator has higher precedence that the multiplication operator. Asking for help, clarification, or responding to other answers. Disconnect between goals and daily tasksIs it me, or the industry? error: comparison between pointer and integer ('int' and 'string' (aka 'char *')), CS50 Caesar program is working but check50 says it isn't. // 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. Why is this sentence from The Great Gatsby grammatical? Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. "clang" "-Ilib\libopenvswitch.a.p" "-Ilib" "-I..\lib" "-I." reinterpret_cast<void *>(42)). ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' 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 is known as implicit type casting or type promotion, compiler automatically converts smaller data type to larger data type. that any valid pointer to void can be converted to this type, then windows meson: cast to smaller integer type 'unsigned long' from 'void *'. Type casting is when you assign a value of one primitive data type to another type. @DietrichEpp can you explain what is race condition with using. 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. 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. The following behavior-changing defect reports were applied retroactively to previously published C++ standards. Functions return bigint only if the parameter expression is a bigint data type. For a fairly recent compiler (that supports C99) you should not store or represent address as plain int value. This method will not work on 64 bit Big Endian platform, so it unnecessarily breaks portability. Does a summoned creature play immediately after being summoned by a ready action? The problem just occur with Xcode 5.1. If you convert (void*) to (long) no precision is lost, then by assigning the (long) to an (int), it properly truncates the number to fit. Hence there is no loss in data. 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). To learn more, see our tips on writing great answers. 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 *'. This is memory reinterpretation - a completely unacceptable way to do what the OP is trying to do. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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. From that point on, you are dealing with 32 bits. For the Nozomi from Shinagawa to Osaka, say on a Saturday afternoon, would tickets/seats typically be available - or would you need to book? For integer casts in specific, using into() signals that . @DavidHeffernan I rephrased that sentence a little. 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. You are getting warnings due to casting a void* to a type of a different size. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? 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. Connect and share knowledge within a single location that is structured and easy to search. ^~~~~~~~~~~~~~~~~~~~~ To cast such pointers to 32-bit types and vice versa special functions are used: void * Handle64ToHandle ( const void * POINTER_64 h ) void * POINTER_64 HandleToHandle64 ( const void *h ) long HandleToLong ( const void *h ) unsigned long HandleToUlong ( const void *h ) Using an integer address (like &x) is probably wrong, indeed each modification you will execute on x will affect the pass behaviour. ), Styling contours by colour and by line thickness in QGIS. Java Type Casting. Even though what you say regarding the lifetime of the object is true, integral types are too limited for a generic API. 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 Can I tell police to wait and call a lawyer when served with a search warrant? This allows you to reinterpret the void * as an int. 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. How to convert a factor to integer\numeric without loss of information? ../lib/odp-util.c:5834:5: error: cast to smaller integer type 'unsigned long' from 'void *' [-Werror,-Wvoid-pointer-to-int-cast] } SCAN_END_SINGLE(ATTR) Well occasionally send you account related emails. The difference between the phonemes /p/ and /b/ in Japanese, Styling contours by colour and by line thickness in QGIS. This explicit cast clearly tells the compiler "Shut up, I know that this code does not look correct, but I do know what I am doing". Is pthread_join a must when using pthread in linux? I need to cast the int from the first function so that I can use it as an argument for the second function. Keep in mind that thrArg should exist till the myFcn() uses it. Why does setupterm terminate the program? 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 This is flat out wrong. While working with Threads in C, I'm facing the warning, "warning: cast to pointer from integer of different size". Making statements based on opinion; back them up with references or personal experience. 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. 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. lexborisov Modest Public. @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. SCAN_PUT(ATTR, NULL); SCAN_PUT_ATTR(key, ATTR, skey, FUNC); 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. SQL Server does not automatically promote . . What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? This page has been accessed 1,655,678 times. -1, Uggh. I wish that you write those answer first than the explanation. SCAN_PUT(ATTR, NULL); The preprocesor absolutely will not perform arithmetic. 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. Half your pointer will be garbage. What is the purpose of non-series Shimano components? When is casting void pointer needed in C? Connect and share knowledge within a single location that is structured and easy to search. 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 Click to see the query in the CodeQL repository. 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. converted back to pointer to void, and the result will compare equal Terrible solution. What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. Are there tables of wastage rates for different fruit and veg? Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? To learn more, see our tips on writing great answers. The cast back to int * is not, though. rev2023.3.3.43278. There's no proper way to cast this to int in general case. Converts between types using a combination of implicit and user-defined conversions. If the function had the correct signature you would not need to cast it explicitly. It is done by the compiler on its own, without any external trigger from the user. Whats the grammar of "For those whose stories they are"? 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 [.]) 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. Disconnect between goals and daily tasksIs it me, or the industry? 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. So make sure you understand what you are doing! Can I tell police to wait and call a lawyer when served with a search warrant? x is a local variable and its lifetime ends as soon as control leaves the scope it was defined in. 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. Based on the design of this function, which modification is right. (int*)Pc = pa; After the execution of the above code all the three pointers, i.e., Pa, Pd, and Pc, point to the value 150. Pull requests. The text was updated successfully, but these errors were encountered: You signed in with another tab or window. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. There's no proper way to cast this to int in general case. 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. C99 defines the types "intptr_t" and "uintptr_t" which do . static_cast on the other hand should deny your stripping away the const qualifier. Find centralized, trusted content and collaborate around the technologies you use most. What I am saying is that it would be safer to use new(5) rather than 5 and deal with it appropriately at the other end. 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. Returns a value of type new-type.