What is the use of memcpy in c

memcpy is used to copy memory blocks. Its uses include: 1) performing shallow copies of memory blocks; 2) moving data blocks; 3) initializing memory; 4) copying structures with simple layouts.

Purpose of memcpy

memcpy is a function in the C language standard library that is used to copy memory blocks. Its syntax is as follows:

void *memcpy(void *dest, const void *src, size_t n);

Where:

• dest: target memory address.
• src: Source memory address.
• n: Number of bytes to copy.

The main uses of memcpy are as follows:

Shallow copy

memcpy can be used to perform a shallow copy of a block of memory, which means copying the block content, but other memory pointed to by the pointer will not be copied. This is different from pointer assignment, which creates a new pointer to the same block of memory rather than creating a copy of the new block.

Data Movement

memcpy can be used to move blocks of data in memory, such as adjusting data location after memory allocation or deallocation.

Initializing memory

memcpy can be used to initialize a block of memory to a specific value or pattern, such as initializing all bytes to 0.

Structure Copy

memcpy can be used to copy structures with a simple layout where all members are simple data types (e.g. integers, characters). For structures containing pointer members or complex layouts, specialized copy functions are required.

Example

// 复制 10 个字节从源数组到目标数组
int src[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
int dest[10];
memcpy(dest, src, 10 * sizeof(int));

After doing this, the dest array will contain a copy of the src array.

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