char buf[1024]; memset(buf, 0, sizeof(buf)); memcpy(buf, &msg, sizeof(msg));

void* src, size_t count);

This function copies a block of memory from a source address to a destination address. It takes three arguments: the destination buffer (buf), the source buffer (src), and the number of bytes to copy (count). It returns a pointer to the destination buffer.

In this specific example, the function is being used to clear the contents of the buf array by setting all its elements to zero. The memset function is called with buf as its first argument, 0 as its second argument (which represents the value to set each byte to), and sizeof(buf) as its third argument (which specifies the number of bytes to set). Then, the memcpy function is called to copy the contents of the src buffer (which is not defined in the provided code) into buf.