Replacing broken pins/legs on a DIP IC package, AC Op-amp integrator with DC Gain Control in LTspice. It is commonly called a pointer to T and its type is T*. Click to see the query in the CodeQL repository. 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). It is easier to understand and write than any other assembly language. SCAN_PUT(ATTR, NULL); This is flat out wrong. ../lib/odp-util.c:5489:33: note: expanded from macro 'SCAN_PUT_ATTR' this way I convert an int to a void* which is much better than converting a void* to an int. The correct answer is, if one does not mind losing data precision. Well occasionally send you account related emails. The 32 remaining bits stored inside int are insufficient to reconstruct a pointer to the thread function. Since gcc compiles that you are performing arithmetic between void* and an int (1024). Now, what happens when I run it with the thread sanitizer? Implementing From will result in the Into implementation but not vice-versa. I have looked around and can't seem to find any information on how to do this. [] 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). rev2023.3.3.43278. 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. what happens when we typecast normal variable to void* or any pointer variable? SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); Fork 63. I'm trying to learn pthreads and thing that keeps bugging me is how do i really pass argument to the function. Using printf with a pointer to float gives an error, Meaning of int (*) (int *) = 5 (or any integer value), Casting int to void* loses precision, and what is the solution in required cases, Acidity of alcohols and basicity of amines. 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. The text was updated successfully, but these errors were encountered: Hence there is no loss in data. 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! It is done by the compiler on its own, without any external trigger from the user. Implementation-dependent. Well it does this because you are converting a 64 bits pointer to an 32 bits integer so you loose information. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? and how to print the thread id of 2d array argument? If you need to keep the returned address, just keep it as void*. 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. 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. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. My code is all over the place now but I appreciate you all helping me on my journey to mastery! The program can be set in such a way to ask the user to inform the type of data and . Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Setting a buffer of char* with intermediate casting to int*. Connect and share knowledge within a single location that is structured and easy to search. If not, check the pointer size on your platform, define these typedefs accordingly yourself and use them. to your account, [87/252] Compiling C object lib/libopenvswitch.a.p/odp-util.c.obj But then you need to cast your arguments inside your thread function which is quite unsafe cf. Mutually exclusive execution using std::atomic? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. What video game is Charlie playing in Poker Face S01E07? ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Your first example is risky because you have to be very careful about the object lifetimes. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? If the function had the correct signature you would not need to cast it explicitly. Making statements based on opinion; back them up with references or personal experience. @DavidHeffernan, sane thread APIs wouldn't send integral data to the thread procedures, they would send pointers. You are correct, but cocos actually only uses that address as a unique id. a cast of which the programmer should be aware of what (s)he is doing. You need to pass an actual pointer. 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. 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; LLNL's tutorial is bad and they should feel bad. 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. 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. Thanks for pointing that out. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? If you preorder a special airline meal (e.g. 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;. As was pointed out by Martin, this presumes that sizeof(void*)>=sizeof(int). The reinterpret_cast makes the int the size of a pointer and the warning will stop. You think by casting it here that you are avoiding the problem! 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; You cannot just cast the 32-bit variable to a pointer, because that pointer on a 64-bit machine is twice as long. For the Nozomi from Shinagawa to Osaka, say on a Saturday afternoon, would tickets/seats typically be available - or would you need to book? In such a case the programmer can use a void pointer to point to the location of the unknown data type. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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. Windows has 32 bit long only on 64 bit as well. However, I believe that even if the define was for the "65536", it would not be what @kaetzacoatl wanted. You are just making it bigger by tricking the compiler and the ABI. 471,961 Members | 900 Online. Why did Ukraine abstain from the UNHRC vote on China? This allows you to reinterpret the void * as an int. 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. 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. Visit Microsoft Q&A to post new questions. Using Kolmogorov complexity to measure difficulty of problems? byte -> short -> char -> int -> long -> float -> double. @DavidHeffernan I rephrased that sentence a little. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. Only the following conversions can be done with static_cast, except when such conversions would cast away constness or volatility. this way you won't get any warning. And in this context, it is very very very common to see programmers lazily type cast the. B language was designed to develop . The dynamic_cast<>operator provides a way to check the actual type of a pointer to a polymorphic class. And you can't pass a pointer to a stack based object from the other thread as it may no longer be valid. You are getting warnings due to casting a void* to a type of a different size. You use the address-of operator & to do that. You may declare a const int variable and cast its reference to the void*. (void *)i Error: cast to 'void *' from smaller integer type 'int'. Acidity of alcohols and basicity of amines. Connect and share knowledge within a single location that is structured and easy to search. Offline ImPer Westermark over 11 years ago in reply to Andy Neil Except that you sometimes stores an integer in the pointer itself. Such a downcast makes no runtime checks to ensure that the object's runtime type is actually D, and may only be used safely if this precondition is guaranteed by other means, such as when implementing static polymorphism. Yesterday, I updated Xcode to the newest version (5.1 (5B130a)) to compatible with iOS 7.1. I guess the other important fact is that the cast operator has higher precedence that the multiplication operator. Making statements based on opinion; back them up with references or personal experience. vegan) just to try it, does this inconvenience the caterers and staff? How Intuit democratizes AI development across teams through reusability. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. Put your define inside a bracket: without a problem. 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. Connect and share knowledge within a single location that is structured and easy to search. return ((void **) returnPtr);} /* Matrix() */. 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. 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. Mutually exclusive execution using std::atomic? 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? Any help with this is appreciated. 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. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. to the original pointer: The following type designates an unsigned integer type with the Why is there a voltage on my HDMI and coaxial cables? SCAN_PUT(ATTR, NULL); The problem is not with casting, but with the target type loosing half of the pointer. You can only do this if you use a synchronization primitive to ensure that there is no race condition. reinterpret_cast<void *>(42)). On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. privacy statement. Error while setting app icon and launch image in xcode 5.1. a is of type int[4], which can be implicitly cast to int* (ie, a pointer to an int) &a is of type int(*)[4] (ie: a pointer to an array of 4 ints). Since all pointers on 64-bit Windows are 64 bits, you are growing the data size from 32 bits backto 64 bits. 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). whether it was an actual problem is a different matter though. Press question mark to learn the rest of the keyboard shortcuts. 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 is the purpose of non-series Shimano components? 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; Whats the grammar of "For those whose stories they are"? 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 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. @Martin York: No, it doesn't depend on endiannness. 10) A prvalue of type pointer to void (possibly cv-qualified) can be converted to pointer to any object type. Remembering to delete the pointer after use so that we don't leak. If you are going to pass the address you typically need to exert some more control over the lifetime of the object. 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" (. FAILED: lib/libopenvswitch.a.p/odp-util.c.obj ncdu: What's going on with this second size column? for (i=0, j=0; jinteger 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. Again, all of the answers above missed the point badly. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? How do I align things in the following tabular environment? This method will not work on 64 bit Big Endian platform, so it unnecessarily breaks portability. How can this new ban on drag possibly be considered constitutional? For a fairly recent compiler (that supports C99) you should not store or represent address as plain int value. *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 . Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? 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. How do I force make/GCC to show me the commands? 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. I am an entry level C programmer. There is absolutely not gurantee that sizeof(int) <= sizeof(void*). However the actual code in question contains an explicit c-style cast to int. Taking the above declarations of A, D, ch of the . Remarks. 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. He should pass the address of the integer, the thread should get that address, Note: This is only appropriate is you cast the.