Can memcpy given value as source address in c

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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 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.

c - Understanding the source code of memcpy() - Stack Overflow

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, … WebNov 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. china moon rover pics

c++ - Can I call memcpy() and memmove() with "number of …

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 … WebMay 28, 2009 · which is actually just the reverse of the memcpy () you did to get the pointer there in the first place. Although, treating the pointer as an int: int addressOfArgTwo = (unsigned int)buff; is also dangerous, if you're moving between 32-bit and 64-bit architectures, as Michael pointed out. Pointers aren't always 32-bit integers. 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 … china moon rover latest

c - memcpy takes virtual address or physical address? - Stack …

Using memcpy to read two integers from a memory block

WebJan 22, 2024 · Some (most) implementations of memcpy() assume that it can copy data in one specific direction which will cause data to be corrupted if areas overlap in the wrong way (e.g. if the implementation uses the "lowest address first" direction and the destination area overlaps and is at a higher address than the source, then writes to the destination ... grainline of fabricWebOct 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. grain line of fabric

"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(): … " - Can memcpy given value as source address in c

Can memcpy given value as source address in c

Using memset for integer array in C - Stack Overflow

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. 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 ...

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WebDec 11, 2010 · In general, memcpy is implemented in a simple (but fast) manner. Simplistically, it just loops over the data (in order), copying from one location to the other. … WebApr 28, 2011 · If you have larger chunk of data to store, use memcpy or memmove with that address to copy data from/to it, like this: #include int main () { const char data …

WebApr 8, 2024 · You can certainly use memcpy (c1->ques, q1->ques, string_size). But it's non-standard for a string copy operation and reduces readability. – selbie Apr 8, 2024 at 3:35 Add a comment 1 In C parameters are passed by value rather than by reference. 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 = {};

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 … WebJun 24, 2015 · no, it's like *ptr = value;. memcpy takes the address of both source and destination. value must have type char * and ptr have type char ** (although you could …

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 …

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 china moon somerset njWebAug 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 … grain line meaningWebJul 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 … grainline on fabricWebJun 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 … china moon taftvilleWebMar 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. … china moon tv showWebNov 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 … china moon south washington ave scranton paWebJan 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 + … china moon rover pictures from earth