Join Bytes to post your question to a community of 472,246 software developers and data experts. Thanks in A colleague asked me something along the lines of the following today. Unexpected uint64 behaviour 0xFFFF'FFFF'FFFF'FFFF - 1 = 0? cast to void *' from smaller integer type 'int cast to void *' from smaller integer type 'int. Find centralized, trusted content and collaborate around the technologies you use most. ", "!"? pcs leave before deros; chris banchero brother; tc dimension custom barrels; cast void pointer to char array. Where can I find a clear diagram of the SPECK algorithm? Visit Microsoft Q&A to post new questions. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Did the drapes in old theatres actually say "ASBESTOS" on them? Even if you are compiling your program for a 32-bit computer, you should fix your code to remove these warnings, to ensure your code is easily portable to 64-bit. You can use a 64 bits integer instead howerver I usually use a function with the right prototype and I cast the function type : Is "I didn't think it was serious" usually a good defence against "duty to rescue"? I usually have all automatic conversion warnings effective when developing in C, and I use explicit casting in order to suppress a specific . Why did DOS-based Windows require HIMEM.SYS to boot? Typical examples include numeric conversion to a type that has less precision or a smaller range, and conversion of a base-class instance to a derived class. The main point is: a pointer has a platform dependent size. There are ways to prevent this: pass a dynamic allocated argument if your not the passing thread is not static or if your argument is a local variable, otherwise there is no issue. 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). 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. What does 'They're at four. Because C# is statically-typed at compile time, after a variable is declared, it cannot be declared again or assigned a value of another type unless that type is implicitly convertible to the variable's type. A boy can regenerate, so demons eat him for years. For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. You use the address-of operator & to do that. So, when you cast a (void*) to (long), you are losing 32 bits of data in the conversion. The reinterpret_cast makes the int the size of a pointer and the warning will stop. Why does Acts not mention the deaths of Peter and Paul? Canadian of Polish descent travel to Poland with Canadian passport, Two MacBook Pro with same model number (A1286) but different year, Folder's list view has different sized fonts in different folders. this way you won't get any warning. I'm not sure how to tell Clang (it's tools, really) that the platform is a 32-bit platform and to stop complaining. some reading around on it and why it is sometimes used. Which ability is most related to insanity: Wisdom, Charisma, Constitution, or Intelligence? I would create a structure and pass that as void* to pthread_create. OP said he doesn't want it. Basically its a better version of (void *)i. If the data types are compatible, then Java will perform the conversion automatically known as Automatic Type Conversion, and if not then they need to be cast or converted explicitly. Run this code to find how Java handles division and what casting can do to the results. Interpreting non-statistically significant results: Do we have "no evidence" or "insufficient evidence" to reject the null? for (i=0, j=0; j header from libstdc++ 5.4.0 with clang 7.0.1 for ARM. does lazarbeam have a wife; Books. I am using the UDF of the Ansys Manual Book as a base for what I intended, but I am trying to incorporate a second component to my condensable mixture, being methanol . equal to the original pointer: First you are using a define, which is not a variable. How can I control PNP and NPN transistors together from one pin? This rule is particularly true for integer values that originate from untrusted sources and are used in any of the following ways: Integer operands of any pointer arithmetic, including array indexing Thanks for contributing an answer to Stack Overflow! Just want to point out that the purpose of threads is, +1 absolutely true, but if you take you time to write struct {}, you can save a lot of troubles in the future when you want to receive/send more data then just an int. What were the most popular text editors for MS-DOS in the 1980s? 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. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. It does not because. Surely the solution is to change the type of ids from int to type that is sufficiently large to hold a pointer. Please unaccept the answer you have chosen as it is wrong (as the comments below it say) and will lead to bugs. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. Can my creature spell be countered if I cast a split second spell after it? On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. Ubuntu won't accept my choice of password, Adding EV Charger (100A) in secondary panel (100A) fed off main (200A), Passing negative parameters to a wolframscript. This is memory reinterpretation - a completely unacceptable way to do what the OP is trying to do. Explanation Only the following conversions can be done with static_cast, except when such conversions would cast away constness or volatility . How a top-ranked engineering school reimagined CS curriculum (Ep. You cannot just cast the 32-bit variable to a pointer, because that pointer on a 64-bit machine is twice as long. 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. BUT converting a pointer to void* and back again is well supported (everywhere). But to answer your question: No, you can't disable it, though you can work around it. User without create permission can create a custom object from Managed package using Custom Rest API. I can easily imagine a situation where rewriting code using, Disabling "cast from pointer to smaller type uint32_t" error in Clang, https://github.com/llvm-mirror/clang/blob/release_50/include/clang/Basic/DiagnosticSemaKinds.td#L6193, https://github.com/llvm-mirror/clang/blob/release_50/lib/Sema/SemaCast.cpp#L2112, How a top-ranked engineering school reimagined CS curriculum (Ep. To learn more, see our tips on writing great answers. Can I use an 11 watt LED bulb in a lamp rated for 8.6 watts maximum? 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. As shown in the following example, a type cast that fails at run time will cause an InvalidCastException to be thrown. I am an entry level C programmer. 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. Connect and share knowledge within a single location that is structured and easy to search. Making statements based on opinion; back them up with references or personal experience. Storage management is an important module of database, which can be subdivided into memory management and external memory management. Write values of different data types in sequence in memory? And you can't pass a pointer to a stack based object from the other thread as it may no longer be valid. In 64-bit programs, the size of the pointer is 64 bits, and cannot be put into the int type, which remains 32-bit in almost all systems. Put your define inside a bracket: #define M_TABLE_SIZE (64*1024) Now, you can do: static const void* M_OFFSET = (void*) M_TABLE_SIZE; without a problem. What is the correct method to cast an int to a void*? Two MacBook Pro with same model number (A1286) but different year. Why don't we use the 7805 for car phone chargers? how to cascade 2d int array to 2d void pointer array? 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. In C#, you can perform the following kinds of conversions: Implicit conversions: No special syntax is required because the conversion always succeeds and no data will be lost. You can then disable this diagnostic completely by adding -Wno-extra-tokens (again, the "extra tokens" warning is an example), or turn it into a non-fatal warning by means of -Wno-error=extra-tokens. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Implementation-dependent. In this case, casting the pointer back to an integer is meaningless, because . Or keep using a C cast even when C++ code compiled as C++. A nit: in your version, the cast to void * is unnecessary. Does it effect my blogs SEO rankings? ), For those who are interested. I agree passing a dynamically allocated pointer is fine (and I think the best way). 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. The next Access Europe Meeting is on Wed 3 May 2023. "I think what you should do is actually pass the address of the variable to the function" Not necessarily. Can I use the spell Immovable Object to create a castle which floats above the clouds? How create a simple program using threads in C? I think that's what you want: // Declaration uint8_t *myData; void loop () { myData = "custom string"; } Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, You should be doing int x = *((int *)arg); You are casting from void * to int that is why you get the warning. The following program casts a double to an int. If any, how can the original function works without errors if we just ignore the warning. long guarantees a pointer size on Linux on any machine. void *ptr; int n = (int)ptr; So in c++ i tried below int n = atoi (static_cast<const char*> (ptr)); This crashes when i run. Thus as a result it may be less error prone to generate a pointer dynamcially and use that. Convert integers, floating-point values and enum types to enum types. This is a fine way to pass integers to new pthreads, if that is what you need. Use returnPtr[j] = (void *) ((long)ptr + i); ). How to make compiler not show int to void pointer cast warnings, incompatible pointer types assigning to 'void (*)(void *)' from 'int (int *)'. How to use Clang static analyzer with a Cortex-M project? Youll be auto redirected in 1 second. There is absolutely not gurantee that sizeof(int) <= sizeof(void*). Can anybody explain how to pass an integer to a function which receives (void * ) as a parameter? You are right! (void *)(long)i, Copyright 2011-2023 SegmentFault. Many errors come from warnings. Boolean algebra of the lattice of subspaces of a vector space? /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey. Remembering to delete the pointer after use so that we don't leak. Nov 14 '05
static const void* M_OFFSET = (void*)64*1024; Since gcc compiles that you are performing arithmetic between void* and an int ( 1024 ). This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s). I guess the other important fact is that the cast operator has higher precedence that the multiplication operator. @ok For more information, see Polymorphism. This method will not work on 64 bit Big Endian platform, so it unnecessarily breaks portability. What would you do next year when you need to port it to yet another experimental hardware? Making statements based on opinion; back them up with references or personal experience. Thanks for contributing an answer to Stack Overflow! Connect and share knowledge within a single location that is structured and easy to search. 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. If you are going to pass the address you typically need to exert some more control over the lifetime of the object. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Making statements based on opinion; back them up with references or personal experience. How to force Unity Editor/TestRunner to run at full speed when in background? A good thing in general, but if you want to disable the warning, just do it. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. The 32 remaining bits stored inside int are insufficient to reconstruct a pointer to the thread function. So you could do this: Note: As sbi points out this would require a change on the OP call to create the thread. However, I believe that even if the define was for the "65536", it would not be what @kaetzacoatl wanted. For example, a variable of type long (64-bit integer) can store any value that an int (32-bit integer) can store. 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. 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). If the function had the correct signature you would not need to cast it explicitly. eg. For a complete list of all implicit numeric conversions, see the Implicit numeric conversions section of the Built-in numeric conversions article. Thank you all for your feedback. is there such a thing as "right to be heard"? 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. MIP Model with relaxed integer constraints takes longer to solve than normal model, why? Please help me with the right way to convert void* to int in c++ Mar 30, 2020 at 10:44am George P (5286) Maybe try reinterpret_cast? This is not a conversion at all. Conversions with helper classes: To convert between non-compatible types, such as integers and System.DateTime objects, or hexadecimal strings and byte arrays, you can use the System.BitConverter class, the System.Convert class, and the Parse methods of the built-in numeric types, such as Int32.Parse. In 64-bit programs, the size of the pointer is 64 bits and it cannot be put into the int type that remains 32-bit almost in all the systems. how about using uintptr_t, most of your pointer arithmetic may still works. This will get you a pointer from a 32 bit offset: A function pointer is incompatible to void* (and any other non function pointer). MIP Model with relaxed integer constraints takes longer to solve than normal model, why? If you do this, you have the thread reference a value that (hopefully still) lives in some other thread. How can I control PNP and NPN transistors together from one pin? Rep Power: 3. How do I check if a string represents a number (float or int)? "Signpost" puzzle from Tatham's collection. The proper way is to cast it to another pointer type. I don't see how anything bad can happen . is returned by the malloc. If you call your thread creation function like this, then the void* arriving inside of myFcn has the value of the int you put into it. Put your define inside a bracket: without a problem. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. In the following example, the compiler implicitly converts the value of num on the right to a type long before assigning it to bigNum. Passing negative parameters to a wolframscript, Generating points along line with specifying the origin of point generation in QGIS. Why is it shorter than a normal address? Examples include conversions from smaller to larger integral types, and conversions from derived classes to base classes. elizabeth guevara don ho; how to send coffee truck in korea; masala hut sheraton maldives menu; tennis player died today; 957103591e449b3c6cadab7 luke combs caleb pressley high school; replace uint32_t by uintptr_t wholesale, then fix remaining cases one by one. Find centralized, trusted content and collaborate around the technologies you use most. Is "I didn't think it was serious" usually a good defence against "duty to rescue"? This forum has migrated to Microsoft Q&A. returnPtr = (void **) malloc (x * sizeof(void *)); ptr = (void *) malloc (x * y * size);
565), Improving the copy in the close modal and post notices - 2023 edition, New blog post from our CEO Prashanth: Community is the future of AI. You are getting warnings due to casting a void* to a type of a different size. Should I re-do this cinched PEX connection? Casting arguments inside the function is a lot safer. Which was the first Sci-Fi story to predict obnoxious "robo calls"? This is not even remotely "the correct answer". However, this specific error is not due to a warning and I can't find any option to disable errors (makes sense, since most errors are fatal). Please start a new discussion. If so, is u32 -> u8) will truncate Casting from a smaller integer to a larger integer (e.g. Casting int to void* loses precision, and what is the solution in required cases, c++: cast from "const variable*" to "uint32" loses precision, cast from 'char*' to 'int' loses precision. */void **MatrixIB (unsigned long x, unsigned long y, int size){ void *ptr; void **returnPtr; register unsigned long i, j;
Asking for help, clarification, or responding to other answers. Why are players required to record the moves in World Championship Classical games? The C Standard allows any object pointer to be cast to and from void *. What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. It's always a good practice to put your #define's in brackets to avoid such surprise. How should a standardized and beautiful flowchart be designed? 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. Has the cause of a rocket failure ever been mis-identified, such that another launch failed due to the same problem? Who has a solution to casting from int to void* and back to int, http://www.ungerhu.com/jxh/clc.welcome.txt, http://benpfaff.org/writings/clc/off-topic.html. Casting is required when information might be lost in the conversion, or when the conversion might not succeed for other reasons. Converting a void* to an int is non-portable way that may work or may not! On most platforms pointers and longs are the same size, but ints and pointers often are not the same size on 64bit platforms. I am looking to clean up the [-Wextra-tokens] (if it doesn't, remove the -fno-diagnostics-show-option flag). Then he wants to convert px to Hello, A boy can regenerate, so demons eat him for years. Say I want to make Solution 1. Definition: C++ introduced a different cast system from C that distinguishes the types of cast operations. You might want to typedef, You should change your code to handle this. rev2023.5.1.43405. Asking for help, clarification, or responding to other answers. To learn more, see our tips on writing great answers. Don't do that. what happens when we typecast normal variable to void* or any pointer variable? 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; rev2023.5.1.43405. These kinds of operations are called type conversions. When is casting void pointer needed in C? Which was the first Sci-Fi story to predict obnoxious "robo calls"? He also rips off an arm to use as a sword, Two MacBook Pro with same model number (A1286) but different year. I agree that you should bite the bullet and fix the code to use the correct integer type. Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey, xcode build error: Semantic issue cast from pointer to smaller type 'int' loses information. following block Hello, Since gcc compiles that you are performing arithmetic between void* and an int (1024). 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.
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