2024 Can memcpy given value as source address in c

Can memcpy given value as source address in c

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August undefined, 2024

WebFeb 16, 2013 · As such, it has no address which could be given as parameter to memcpy or another function that expects a memory location. If you want to do this, you need to have a real constant (such as const int ), as suggested in the other answers. WebJun 18, 2016 · The type of the expression msg.data is different from the type of the expression &msg.data, but the values are identical. Since this is C++, the behavior is …

How to copy arrray to array using memcpy () in C

WebOct 11, 2024 · When you refer to the address of a pointer, this normally means the pointer's own location in memory, not the value it holds (which also is an address). – Andreas Wenzel Oct 11, 2024 at 4:55 1 @N001: If you follow the advice I gave in my first comment, does your program then work as intended? Both printed pointer values are the same, then. WebJun 21, 2014 · The memcpy function copies n characters from the object pointed to by s2 into the object pointed to by s1. If copying takes place between objects that overlap, the … new writings in sf

C++ memcpy return value - Stack Overflow

WebApr 8, 2024 · Also remember that argument in C are passed by value, meaning the value is copied into the argument variable. Modifying the argument variable (like assigning to it) … WebOct 21, 2014 · But memcpy () is about copying memory objects, not values. An object resides at a given address, and contains a given value. Taking n gives the value, … WebMar 12, 2016 · As Paul Ogilvie correctly explained, memcpy deals with user space addresses. As such they are virtual addresses, not necessarily physical addresses. Yet there is a possibility for very large areas with very specific alignment characteristics to optimize memcpy by requesting the OS to remap some of the destination virtual … new writing submissions

c - memcpy() vs memmove() - Stack Overflow

c - Is it safe to memcpy to the exact same region? - Stack Overflow

WebNov 27, 2024 · No, you can't [portably] use memset for that purpose, unless the desired target value is 0.memset treats the target memory region as an array of bytes, not an array of ints.. A fairly popular hack for filling a memory region with a repetitive pattern is actually based on memcpy.It critically relies on the expectation that memcpy copies data in … WebOct 25, 2015 · Save it to a .c file, like test.c, and compile it using gcc, like this: It will (most likely) behave differently. Try replacing memcpy with strncpy and see what happen. I hope the example is useful. With memcpy, the destination cannot overlap the source at all. With memmove it can. new writing structuresWebFeb 16, 2013 · Your constant (macro) is really just a literal. As such, it has no address which could be given as parameter to memcpy or another function that expects a … milad e sherif 2023

"WebApr 29, 2004 · Optimizing Memcpy improves speed. Knowing a few details about your system-memory size, cache type, and bus width can pay big dividends in higher performance. The memcpy () routine in every C … " - Can memcpy given value as source address in c

Can memcpy given value as source address in c

WebSo the answer is no; the check is not necessary (or yes; you can pass zero). Share Improve this answer Follow edited Sep 22, 2012 at 10:42 answered Sep 20, 2010 at 13:32 Mike Seymour 248k 28 442 637 1 Would a pointer be considered "valid" for purposes of such a function if it pointed to the location following the last element of an array? WebJun 4, 2013 · I need a function that stores data into a void pointer. Here is a simple example of it: void saveData (void* data) { char inputData [] = "some data"; memcpy ( (char*)data, inputData, sizeof (inputData)); } However I get segmentation errors when I do this, even though it compiles just fine. My function argument has to be a void pointer because I ...

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WebAug 12, 2015 · In Win32 API programming it's typical to use C struct s with multiple fields. Usually only a couple of them have meaningful values and all others have to be zeroed out. This can be achieved in either of the two ways: STRUCT theStruct; memset ( &theStruct, 0, sizeof ( STRUCT ) ); or. STRUCT theStruct = {}; WebFeb 29, 2016 · You can just cast the char* to an int* and work with that seeing as you know you always have a valid 8-byte region to write to. char *data; …

WebOct 3, 2024 · 2 Answers. Sorted by: 5. It's how memcpy works: it takes a pointer to data it will copy. Your data is pointer to float, so you need to pass pointer to pointer to float: #include int main () { float f = 20.0f; float* pf = &f; char data [sizeof (pf)]; memcpy (data, &pf, sizeof (data)); } Share. WebApr 17, 2012 · I am trying to read two integers, stored consecutively, from a memory block (i have a pointer void *block pointing to the contents of the block) using memcpy. The first one is read just fine using: memcpy (&test, block, sizeof (int)); I try to read the second using: memcpy (&test, block + sizeof (int), sizeof (int)); (Of course i am having ...

WebJan 7, 2016 · memcpy () is used to copy a block of memory from a location to another. It is declared in string.h // Copies "numBytes" bytes from address "from" to address "to" void * memcpy (void *to, const void *from, size_t numBytes); Below is a sample C program to … Before memset(): GeeksForGeeks is for programming geeks. After memset(): … WebThe C library function void *memcpy (void *dest, const void *src, size_t n) copies n characters from memory area src to memory area dest. Declaration Following is the …

WebMar 18, 2016 · C standard library often supports this technique, memcpy being another example. A possible use case might be something along the lines of char *clone_buffer (const char *buffer, size_t size) { return memcpy (new char [size], buffer, size); } If memcpy did not return the destination buffer pointer, we'd probably have to implement the above as

WebNov 20, 2014 · If you have allocated using malloc you must state the size of the array. int * src = malloc (ARRAY_LENGTH*sizeof (*src)); int * dst1 = malloc … new writing task 2 topics 2021WebAug 3, 2015 · @PSkocik "Character type" is a term-of-art in the C standard which encompasses both single char objects and arrays of them (and probably some other stuff I don't remember off the top of my head). Regardless, the point is that char[4] and int are not compatible types and therefore you cannot use int* to access memory declared as … new writing scotland 40WebJan 21, 2016 · Define you own memcpy to copy to this address space : void my_memcpy( ptr8 addr_dest, const void * src, int len ) { memcpy( my_destination_memory + … new writing south brightonWebOct 2, 2024 · memcpy only copies from the beginning of an array if that's what address you pass it. The name of an array a is synonymous with the address of the first element &a [0], so if you do memcpy (dest, src, size), then the copy will be from the start of the array src. milad horriat winnipegWebMar 28, 2013 · As a basic type safety check it makes sure the sizes of source and destination elements are the same. That's evaluated at compilation time as well. … new writing theatre ukWebNov 3, 2012 · First, memcpy () doesn't succeed or fail in the normal sense. It just copies the data, which might cause a fault/exception if it reads outside the source array or writes outside the destination array, and it might also read or write outside one of those arrays without causing any fault/exception and just silently corrupting data. milad frounchiWebJul 11, 2013 · Understanding the source code of memcpy () 00018 void *memcpy (void *dst, const void *src, size_t len) 00019 { 00020 size_t i; 00021 00022 /* 00023 * memcpy … new writtle street