/** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. I'll edit accordingly. pointer/reference to a derived class pointer/reference. For example, if youwrite ((int*)ptr + 1), it will add 4 bytes to the pointer, because "ints" are 4 bytes each. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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 usually have all automatic conversion warnings effective when developing in C, and I use explicit casting in order to suppress a specific . reinterpret_cast<void *>(42)). 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. c - type casting integer to void* - Stack Overflow This thread has been closed and replies have been disabled. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. does lazarbeam have a wife; Books. 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. how about using uintptr_t, most of your pointer arithmetic may still works. You can use any other pointer, or you can use (size_t), which is 64 bits. The next Access Europe Meeting is on Wed 3 May 2023. [-Wextra-tokens] (if it doesn't, remove the -fno-diagnostics-show-option flag). Convert integers, floating-point values and enum types to enum types. Technically, these casts should therefore be valid. "Signpost" puzzle from Tatham's collection. I want to learn the difference between the three type cast operators: Hi, To avoid truncating your pointer, cast it to a type of identical size. Can I use my Coinbase address to receive bitcoin? I am an entry level C programmer. for (i=0, j=0; j=sizeof(int). cast to void *' from smaller integer type 'int-tdecu credit scoretdecu credit score Then he wants to convert px to Hello, Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey, Setting a buffer of char* with intermediate casting to int*. 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. 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. 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;. A boy can regenerate, so demons eat him for years. Don't pass your int as a void*, pass a int* to your int, so you can cast the void* to an int* and copy the dereferenced pointer to your int. It seems both static_cast and dynamic_cast can cast a base class rev2023.3.3.43278. return ((void **) returnPtr);} /* Matrix() */. The point is (probably) that the value passed to the thread is an integer value, not really a 'void *'. The most general answer is in no way. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. " is pointer to interface, not interface" confusion, Cast from uint8_t pointer to uint32_t integer compilation error. 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; 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? What is the correct method to cast an int to a void*? 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. LettuceConnectionFactory was destroyed and cannot be used - CSDN Based on the design of this function, which modification is right. 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. What is this brick with a round back and a stud on the side used for? I had this error while trying to cross compile the header from libstdc++ 5.4.0 with clang 7.0.1 for ARM. You need to pass an actual pointer. I hit this same problem in a project without C++11, and worked around it like this: Thanks for contributing an answer to Stack Overflow! Share Improve this answer Follow answered May 6, 2018 at 7:24 Rahul (void *)(long)i, Copyright 2011-2023 SegmentFault. # * # (intptr_t) # # warning: cast to pointer from integer of different size # (intptr_t)IDE # (void*) . error: cast from 'void*' to 'int' loses precision - Stack Overflow Why did US v. Assange skip the court of appeal? 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], Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. As for the stack, I've written a few libraries using pthreds, thus I don't agree that what you describe "is quite often the case". Without RTTI your code will be cleaner | Sandor Dargo's Blog Did the drapes in old theatres actually say "ASBESTOS" on them? Why did US v. Assange skip the court of appeal? Youll be auto redirected in 1 second. The reinterpret_cast makes the int the size of a pointer and the warning will stop. 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. pthread passes the argument as a void*. What are the advantages of running a power tool on 240 V vs 120 V? ", "? @Shahbaz you could but I will not suggest to a C newbie to use globals. How can I control PNP and NPN transistors together from one pin? I guess the other important fact is that the cast operator has higher precedence that the multiplication operator. and how to print the thread id of 2d array argument? Since all pointers on 64-bit Windows are 64 bits, you are growing the data size from 32 bits backto 64 bits. C99 defines the types "intptr_t" and "uintptr_t" which do . If the sizes are different then endianess comes into play. how to cascade 2d int array to 2d void pointer array? Did the Golden Gate Bridge 'flatten' under the weight of 300,000 people in 1987? Casting a pointer to void* and back is valid use of reinterpret_cast<>. I am looking to clean up the Asking for help, clarification, or responding to other answers. 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 does setupterm terminate the program? Why does Acts not mention the deaths of Peter and Paul? It is possible for a cast operation that compiles correctly to fail at run time. A. if(x%2=1)y=x;B. if(sqrt(x)%2)y=x;C. if(x==1)y=x;D. if(x==1)y=&x; Cerror: cast to 'void *' from smaller integer type 'int'. 23.04.27, ICP15005796-233010602002000ICP B2-20201554. Or, they are all wrong. Since the 'size' argument for your function is the number of bytes each element in the array needs, I think casting the pointerto (char*) is appropriate. Unless you have a valid address at that value, you are going to invoke undefined behaviour when try to use that pointer. Examples include conversions from smaller to larger integral types, and conversions from derived classes to base classes. No sense in writing a few dozen lines of extra code just to get a bunch of numbered threads. There's no proper way to cast this to int in general case. char **array; To subscribe to this RSS feed, copy and paste this URL into your RSS reader. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. What were the most popular text editors for MS-DOS in the 1980s? I have a question about casting a function pointer. For a fairly recent compiler (that supports C99) you should not store or represent address as plain int value. Types - D Programming Language How a top-ranked engineering school reimagined CS curriculum (Ep. is there such a thing as "right to be heard"? I saw on a couple of recent posts people saying that casting the return long guarantees a pointer size on Linux on any machine. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. 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. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. How to make compiler not show int to void pointer cast warnings, incompatible pointer types assigning to 'void (*)(void *)' from 'int (int *)'. Yeah, the tutorial is doing it wrong. Why did DOS-based Windows require HIMEM.SYS to boot? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Explanation Only the following conversions can be done with static_cast, except when such conversions would cast away constness or volatility . cwindowccwindowsword[3]={"ab"};_ab charPersondebug, A, A, , "C" ???? Cerror: cast to 'void *' from smaller integer type 'int Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey. it often does reinterpret_cast(ptr). 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. For example, you might have an integer variable that you need to pass to a method whose parameter is typed as double. You are getting warnings due to casting a void* to a type of a different size. 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. 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;. eg. For example, the string cannot be implicitly converted to int. Can you still use Commanders Strike if the only attack available to forego is an attack against an ally? I am compiling this program in linux gcc compiler.. again. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. The preprocesor absolutely will not perform arithmetic. To avoid truncating your pointer, cast it to a type of identical size. (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. Or keep using a C cast even when C++ code compiled as C++. If you write ((char*)ptr + 1), it will advance the pointer 1 byte, because a "char" is 1 byte. Here is my code: I already tried (void*)M_TABLE_SIZE but then I get an error that I cannot use the * operator. rev2023.5.1.43405. This is why you got Error 1 C2036, from your post. Disabling "cast from pointer to smaller type uint32_t" error in Clang What would you do next year when you need to port it to yet another experimental hardware? This is a fine way to pass integers to new pthreads, if that is what you need. 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. MIP Model with relaxed integer constraints takes longer to solve than normal model, why? What does 'They're at four. void* -> integer -> void* rather than integer -> void* -> integer. 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. Asking for help, clarification, or responding to other answers. There's no proper way to cast this to int in general case. Join Bytes to post your question to a community of 472,246 software developers and data experts. 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" (. How can I control PNP and NPN transistors together from one pin? Can I use the spell Immovable Object to create a castle which floats above the clouds? Connect and share knowledge within a single location that is structured and easy to search. "I think what you should do is actually pass the address of the variable to the function" Not necessarily. this way I convert an int to a void* which is much better than converting a void* to an int. Half your pointer will be garbage. You can use a 64 bits integer instead howerver I usually use a function with the right prototype and I cast the function type : 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.
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