Basically its a better version of (void *)i. ", "!"? /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. Find centralized, trusted content and collaborate around the technologies you use most. I would like to know the reason. Remembering to delete the pointer after use so that we don't leak. But to just truncate the integer value and not having to fix all the wrong uses of uint32_t just yet, you could use static_cast(reinterpret_cast(ptr)). Run this code to find how Java handles division and what casting can do to the results. For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. Your strategy will not work for stack-allocated objects, be careful!! Connect and share knowledge within a single location that is structured and easy to search. Boolean algebra of the lattice of subspaces of a vector space? This thread has been closed and replies have been disabled. You are just making it bigger by tricking the compiler and the ABI. Can my creature spell be countered if I cast a split second spell after it? Passing negative parameters to a wolframscript, Generating points along line with specifying the origin of point generation in QGIS. For example, a variable of type long (64-bit integer) can store any value that an int (32-bit integer) can store. 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). pthread passes the argument as a void*. You can use a 64 bits integer instead howerver I usually use a function with the right prototype and I cast the function type : Referring to N1570 7.20.1.4/p1 (Integer types capable of holding object pointers): The following type designates a signed integer type with the property 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. Many errors come from warnings. If you are going to pass the address you typically need to exert some more control over the lifetime of the object. 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. 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. Write values of different data types in sequence in memory? this way you won't get any warning. Next, when doing pointer arithmetic, the addition operation will use the pointer's type to determine how many bytes to add to it when incrementing it. Unfortunately, that hardware is 64-bit and the code contains many instances of pointer arithmetic that expects pointers to be 32-bit, i.e. How create a simple program using threads in C? Don't do that. From the question I presume the OP does. Based on the design of this function, which modification is right. Thanks for pointing that out. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. You might want to typedef, You should change your code to handle this. In some reference type conversions, the compiler cannot determine whether a cast will be valid. It seems both static_cast and dynamic_cast can cast a base class Connect and share knowledge within a single location that is structured and easy to search. I saw on a couple of recent posts people saying that casting the return 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. The program will not compile without the cast. You can use any other pointer, or you can use (size_t), which is 64 bits. Converting a void* to an int is non-portable way that may work or may not! Making statements based on opinion; back them up with references or personal experience. even though the compiler doesn't know you only ever pass myFcn to pthread_create in conjunction with an integer. If not, check the pointer size on your platform, define these typedefs accordingly yourself and use them. Please unaccept the answer you have chosen as it is wrong (as the comments below it say) and will lead to bugs. 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. Windows has 32 bit long only on 64 bit as well.
The content you requested has been removed. Could a subterranean river or aquifer generate enough continuous momentum to power a waterwheel for the purpose of producing electricity? Surely the solution is to change the type of ids from int to type that is sufficiently large to hold a pointer. Short story about swapping bodies as a job; the person who hires the main character misuses his body. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Two MacBook Pro with same model number (A1286) but different year. Can I use the spell Immovable Object to create a castle which floats above the clouds? Solution 1. comment:4 by Kurt Schwehr, 8 years ago r28216 removes OGDIDataset:: GetInternalHandle from trunk It is commonly called a pointer to T and its type is T*. Save this piece of code as mycast.hpp and add -include mycast.hpp to your Makefile. cast to void *' from smaller integer type 'int-tdecu credit scoretdecu credit score Alternatively, if you choose to castthe ptr variableto (size_t) instead, then you don't need to worry about the pointer typeanymore. @DietrichEpp can you explain what is race condition with using. 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. I don't understand why the following two cases produce different Hi, I've this question: suppose we have two differently typed pointers: But, sure, in that specific case you can pass a local variable address, type casting integer to void* [duplicate]. Is "I didn't think it was serious" usually a good defence against "duty to rescue"? ", "? My code is all over the place now but I appreciate you all helping me on my journey to mastery! 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 use the address-of operator & to do that. I think the solution 3> should be the correct one. Question is, how do I explain this to Clang? some reading around on it and why it is sometimes used. 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. (Also, check out how it prints "5" twice), passing a unique pointer to each thread wont race, and you can get/save any kind of information in the th struct. 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). In both cases, converting the pointer to an integer type that's too small to represent all pointer values is a bug. 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, Short story about swapping bodies as a job; the person who hires the main character misuses his body. there How should an excellent flowchart be drawn? 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. The most general answer is - in no way. 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. Terrible solution. In C (int)b is called an explicit conversion, i.e. 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 396k 35 399 609 1 Yeah, the tutorial is doing it wrong. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. Why did US v. Assange skip the court of appeal? void* -> integer -> void* rather than integer -> void* -> integer. You are right! Storage management is an important module of database, which can be subdivided into memory management and external memory management. How to set, clear, and toggle a single bit? Episode about a group who book passage on a space ship controlled by an AI, who turns out to be a human who can't leave his ship? Can I use my Coinbase address to receive bitcoin? Use #include to define it. A nit: in your version, the cast to void * is unnecessary. What are the advantages of running a power tool on 240 V vs 120 V? If the types are from the same inheritance tree, then you should either use dynamic_casts or even better, you should benefit from dynamic dispatching.. dynamic_cast is slightly better, but still should be avoided. property that any valid pointer to void can be converted to this type, error: comparison between pointer and integer ('int' and 'string' (aka 'char *')), CS50 Caesar program is working but check50 says it isn't. 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. 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. How do I work around the GCC "error: cast from SourceLocation* to int loses precision" error when compiling cmockery.c? Nov 14 '05
You can insert some debugging/logging logic to Reinterpret_cast if necessary. If the sizes are different then endianess comes into play. This option of Python is missing in matplotlibcpp within Visual Studio -> works only in b/w ! How do I force make/GCC to show me the commands? Can I use my Coinbase address to receive bitcoin? The pointer doesn't actually point to anything, but it's the result of an earlier cast from an integer to a pointer (e.g. Thanks for contributing an answer to Stack Overflow! This method will not work on 64 bit Big Endian platform, so it unnecessarily breaks portability. Say I want to make This code is a bit odd (but a void* can certainly host a int on all architectures on which GDAL can be compiled), and certainly unused by anyone, so you could just remove the GetInternalHandle () implementation as well if you prefer. Why don't we use the 7805 for car phone chargers? Asking for help, clarification, or responding to other answers. i32 -> u32) is a no-op Casting from a larger integer to a smaller integer (e.g. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. -1, Uggh. Therefore, after you declare i as an int, you cannot assign the string "Hello" to it, as the following code shows: However, you might sometimes need to copy a value into a variable or method parameter of another type. What I am trying to do in that line of code is check to make sure each character in my string is alphabetical. u32 -> u8) will truncate Casting from a smaller integer to a larger integer (e.g. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, "what happen when typcating normal variable to void* or any pointer variable?" Where can I find a clear diagram of the SPECK algorithm? It's not them. My blogs h2 and other tags are in these manner. 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;. Visit Microsoft Q&A to post new questions. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. I agree that you should bite the bullet and fix the code to use the correct integer type. 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. Which ability is most related to insanity: Wisdom, Charisma, Constitution, or Intelligence? Convert integers, floating-point values and enum types to enum types. If you really need such trickery, then consider one of dedicated types, which are intptr_t and uintptr_t. The preprocessor will replace your code by this: This is unlikely what you are trying to do. 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. What is this brick with a round back and a stud on the side used for? Does it effect my blogs SEO rankings? To perform a cast, specify the type that you are casting to in parentheses in front of the value or variable to be converted. 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). To learn more, see our tips on writing great answers. What is this brick with a round back and a stud on the side used for? Going through them one by one would be very tedious and since this is an experimental project anyway, I'm happy to settle for a "hackish" workaround. Find centralized, trusted content and collaborate around the technologies you use most. For example, if the pointers in a system are stored in 16 bits, but integers are stored in 8 bits, a total of 8 bits would be lost in the . Wrong. So,solution #3 works just fine. He also rips off an arm to use as a sword. Find centralized, trusted content and collaborate around the technologies you use most. or, Array with multiple data types? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Canadian of Polish descent travel to Poland with Canadian passport. I usually have all automatic conversion warnings effective when developing in C, and I use explicit casting in order to suppress a specific . To avoid truncating your pointer, cast it to a type of identical size. Why did US v. Assange skip the court of appeal? How can I control PNP and NPN transistors together from one pin? Explicitly call a single-argument constructor or a conversion operator. Why don't we use the 7805 for car phone chargers? 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. Find centralized, trusted content and collaborate around the technologies you use most. But then you need to cast your arguments inside your thread function which is quite unsafe cf. for (i=0, j=0; j header from libstdc++ 5.4.0 with clang 7.0.1 for ARM. Casting arguments inside the function is a lot safer. Offline ImPer Westermark over 12 years ago in reply to Andy Neil Except that you sometimes stores an integer in the pointer itself. Since the culprit is probably something like -Wall which enables many warnings you should keep on, you should selectively disable this single warning. Which ability is most related to insanity: Wisdom, Charisma, Constitution, or Intelligence? Get the address of a callback function to call dynamically in C++, error: call of overloaded function ambiguous, error: cast from to unsigned int loses precision [-fpermissive]. This is not even remotely "the correct answer". 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. The only. 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). Why did DOS-based Windows require HIMEM.SYS to boot? In the realm of Android development, two languages have consistently stood out: Java and Kotlin. The only exception is exotic systems with the SILP64 data model, where the size of int is also 64 bits. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. As a result, it is possible to silently convert from one pointer type to another without the compiler diagnosing the problem by storing or casting a pointer to void * and then storing or casting it to the final type. What is the difference between const int*, const int * const, and int const *? From: Hans de Goede <[email protected]> To: Mark Gross <[email protected]> Cc: Hans de Goede <[email protected]>, Andy Shevchenko <[email protected]>, [email protected], kernel test robot <[email protected]> Subject: [PATCH] platform/x86: hp-wmi: Fix cast to smaller integer type warning Date: Mon, 23 Jan 2023 14:28:24 +0100 [thread overview] Message-ID: <20230123132824. . Is a downhill scooter lighter than a downhill MTB with same performance? Making statements based on opinion; back them up with references or personal experience. Instead of using a long cast, you should cast to size_t. Did the drapes in old theatres actually say "ASBESTOS" on them? A boy can regenerate, so demons eat him for years. Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey.
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