Thanks for contributing an answer to Stack Overflow! What is the purpose of non-series Shimano components? SCAN_PUT_ATTR(key, ATTR, skey, FUNC); Asking for help, clarification, or responding to other answers. Replacing broken pins/legs on a DIP IC package, How to handle a hobby that makes income in US. static_cast on the other hand should deny your stripping away the const qualifier. Thanks for pointing that out. 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 What is the purpose of non-series Shimano components? Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? I would create a structure and pass that as void* to pthread_create. If you preorder a special airline meal (e.g. Implementing From will result in the Into implementation but not vice-versa. equal to the original pointer: First you are using a define, which is not a variable. Using Kolmogorov complexity to measure difficulty of problems? Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. what does it mean to convert int to void* or vice versa? For integer casts in specific, using into() signals that . 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). You cannot just cast the 32-bit variable to a pointer, because that pointer on a 64-bit machine is twice as long. actually no, as int my be a smaller type than a pointer ;-) But, of course with int64_t it works fine. But, sure, in that specific case you can pass a local variable address, type casting integer to void* [duplicate]. Disconnect between goals and daily tasksIs it me, or the industry? 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; However even though their types are different, the address is going to be the same. LLNL's tutorial is bad and they should feel bad. What is the correct method to cast an int to a void*? How can this new ban on drag possibly be considered constitutional? Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? 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.. @BlueMoon Thanks a lot! For example, if you want to store a 'long' value into a simple integer then you can type cast 'long' to 'int'. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Your first example is risky because you have to be very careful about the object lifetimes. I don't see how anything bad can happen . Do new devs get fired if they can't solve a certain bug? (void *)i Error: cast to 'void *' from smaller integer type 'int'. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Visit Microsoft Q&A to post new questions. what does it mean to convert int to void* or vice versa? Remarks. But the problem has still happened. By clicking Sign up for GitHub, you agree to our terms of service and As was pointed out by Martin, this presumes that sizeof(void*)>=sizeof(int). How create a simple program using threads in C? 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. Api says this is how i should create thread: So if I want to pass an int what I think I should do is: The second example assumes that a pointer is wide enough to store an int. ../lib/odp-util.c:5601:9: note: expanded from macro 'SCAN_PUT' : iPhone Retina 4-inch 64-bit) is selected. 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 Does melting sea ices rises global sea level? ncdu: What's going on with this second size column? ../lib/odp-util.c:5658:9: note: expanded from macro 'SCAN_END_SINGLE' If int is no larger than pointer to void then one way to store the value is by simply copying the bytes: int i . 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. Since gcc compiles that you are performing arithmetic between void* and an int (1024). You can convert the values from one type to another explicitly using the cast operator as follows (type_name) expression This is known as implicit type casting or type promotion, compiler automatically converts smaller data type to larger data type. Asking for help, clarification, or responding to other answers. To learn more, see our tips on writing great answers. converted back to pointer to void, and the result will compare equal Then i can continue compiling. Why does setupterm terminate the program? This is flat out wrong. If the destination type is bool, this is a boolean conversion (see below). 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. } SCAN_END_SINGLE(ATTR) "I think what you should do is actually pass the address of the variable to the function" Not necessarily. "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. What is the point of Thrower's Bandolier? It is done by the compiler on its own, without any external trigger from the user. I think the solution 3> should be the correct one. Bulk update symbol size units from mm to map units in rule-based symbology. 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. and how to print the thread id of 2d array argument? SCAN_PUT(ATTR, NULL); It solved my problem too. 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). Asking for help, clarification, or responding to other answers. I wish that you write those answer first than the explanation. a cast of which the programmer should be aware of what (s)he is doing. However, you are also casting the result of this operation to (void*). [that could be a TODO - not to delay solving the ICE]. It is commonly called a pointer to T and its type is T*. Hence there is no loss in data. See also this documentation.. From and Into are generally intended to be lossless, infalliable conversions.as on the other hand can discard data and lead to bugs in some situations, for example casting a u64 to a usize may truncate the value on a 32-bit host. -1, Uggh. - the incident has nothing to do with me; can I use this this way? What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. 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; I assumed that gcc makes a 65536 out of my define, but I was wrong. What does it mean to convert int to void* or vice versa? A cast specifies a conversion from one type to another. What is the difference between const int*, const int * const, and int const *? void* -> integer -> void* rather than integer -> void* -> integer. Find centralized, trusted content and collaborate around the technologies you use most. byte -> short -> char -> int -> long -> float -> double. There is no "correct" way to store a 64-bit pointer in an 32-bit integer. 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 Implicit Type Conversion is also known as 'automatic type conversion'. ), Styling contours by colour and by line thickness in QGIS. 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. you can just change architecture to support 32 bit compilation by all below in in Build Settings. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, "what happen when typcating normal variable to void* or any pointer variable?" 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. 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. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. The problem just occur with Xcode 5.1. unsigned long call_fn = (unsigned long)FUNC; It modifies >> Wconversion-real.c, Wconversion-real-integer.c and pr35635.c to be more >> specific > > If the patch passes existing tests, I'd be inclined to leave them > tests alone and add new ones that are specific to what this patch > changes. The text was updated successfully, but these errors were encountered: You signed in with another tab or window. rev2023.3.3.43278. 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 casting from int to void* and back to int. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Mutually exclusive execution using std::atomic? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. ), For those who are interested. Using Kolmogorov complexity to measure difficulty of problems? Sign up for a free GitHub account to open an issue and contact its maintainers and the community. The cast back to int * is not, though. This page has been accessed 1,655,678 times. And when assigning to a void pointer, all type information is lost. @Shahbaz you could but I will not suggest to a C newbie to use globals. Instead of using a long cast, you should cast to size_t. 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. If your standard library (even if it is not C99) happens to provide these types - use them. Or, they are all wrong. 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; 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. Pd = Pa; Similarly, Pc may be type cast to type int and assigned the value Pa. 1. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Thanks for contributing an answer to Stack Overflow! When is casting void pointer needed in C? Bulk update symbol size units from mm to map units in rule-based symbology. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. what happens when we typecast normal variable to void* or any pointer variable? return ((void **) returnPtr);} /* Matrix() */. This will only compile if the destination type is long enough. Why does Mister Mxyzptlk need to have a weakness in the comics? AC Op-amp integrator with DC Gain Control in LTspice. You are getting warnings due to casting a void* to a type of a different size. STR34-C. Already on GitHub? Losing bytes like thisis called 'truncation', and that's what the first warning is telling you. What is the point of Thrower's Bandolier? On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. 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 Find centralized, trusted content and collaborate around the technologies you use most. Cast characters to unsigned char before converting to larger integer sizes Created by Robert Seacord, last modified by Jill Britton on Oct 03, 2022 Signed character data must be converted to unsigned char before being assigned or converted to a larger signed type. What you do here is undefined behavior, and undefined behavior of very practical sort. The only alternative is really to take time and fix all 64-bit code issues, of which there may be some non-trivial issues. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? The preprocessor will replace your code by this: This is unlikely what you are trying to do. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Why is there a voltage on my HDMI and coaxial cables? 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. Evaluate integer expressions in a larger size before comparing or assigning to that size.Note that (time_+t)-1 also complies with INT31-C-EX3. Remembering to delete the pointer after use so that we don't leak. This is what the second warning is telling you. ^~~~~~~~~~~~~~~~~~~~ So make sure you understand what you are doing! 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. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^~~~~~~~~~~~~~~~~~~ rev2023.3.3.43278. The high-order 9 bits of the number are used to hold a flag value, and the result is converted back into a pointer. The difference between a and &a is the type. 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. x is a local variable and its lifetime ends as soon as control leaves the scope it was defined in. Well it does this because you are converting a 64 bits pointer to an 32 bits integer so you loose information. If this is the data to a thread procedure, then you quite commonly want to pass by value. reinterpret_cast is a type of casting operator used in C++. Any help with this is appreciated. This allows you to reinterpret the void * as an int. So you know you can cast it back like this. whether it was an actual problem is a different matter though. As a result of the integer division 3/2 we get the value 1, which is of the int type. To learn more, see our tips on writing great answers. Alternatively, if you choose to castthe ptr variableto (size_t) instead, then you don't need to worry about the pointer typeanymore. Press question mark to learn the rest of the keyboard shortcuts. If your code has the chance to ever be ported to some platform where this doesn't hold, this won't work. Replacing broken pins/legs on a DIP IC package, AC Op-amp integrator with DC Gain Control in LTspice. to your account, [87/252] Compiling C object lib/libopenvswitch.a.p/odp-util.c.obj Returns a value of type new-type. If you need to keep the returned address, just keep it as void*. 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.
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