内存拷贝探究

函数原型：

errno_t memcpy_s(
   void *dest,
   size_t numberOfElements,
   const void *src,
   size_t count 
);

参数：

dest

新的缓冲区。

numberOfElements

目标缓冲区的大小。

src

要复制的缓冲区。

count

字符数。的副本。

测试代码：

// memcpyTest.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include "string" //strlen()需要的头文件

int _tmain(int argc, _TCHAR* argv[])
{
	//-----memcpyPchar_Test_Begin-----------------------------
	// Populate a2 with squares of integers
	char *psourcechar = "aaa";
	char *ptargetchar = /*NULL*/new char[6]; //内存拷贝，需要保证target目标有空间，且要保证空间的大小

	// Tell memcpy to copy 10 ints (40 bytes)(the size of a1)
	memcpy(ptargetchar,psourcechar,sizeof(ptargetchar));    
	ptargetchar[strlen(psourcechar)]='\0';

	printf("%s ", ptargetchar);

	printf("\n");
	//-----memcpyPchar_Test_End-----------------------------

	

	//-----memcpy_Test_Begin-----------------------------
	int memcpya1[10], memcpya2[100], i;

	// Populate a2 with squares of integers
	for (i = 0; i < 100; i++)
	{
		memcpya2[i] = i*i;
	}

	// Tell memcpy to copy 10 ints (40 bytes)(the size of a1)
	memcpy(memcpya1,memcpya2,sizeof(memcpya1) );    
	
	for (i = 0; i < 10; i++)
		printf("%d ", memcpya1[i]);

	printf("\n");
	//-----memcpy_Test_End-----------------------------


	//-----memcpy_s_Test_Begin-----------------------------
	int a1[10], a2[100], j;
	errno_t err;

	// Populate a2 with squares of integers
	for (j = 0; j < 100; j++)
	{
		a2[j] = j*j;
	}

	// Tell memcpy_s to copy 10 ints (40 bytes), giving
	// the size of the a1 array (also 40 bytes).
	err = memcpy_s(a1, sizeof(a1), a2, 10 * sizeof (int) );    
	if (err)
	{
		printf("Error executing memcpy_s.\n");
	}
	else
	{
		for (j = 0; j < 10; j++)
			printf("%d ", a1[j]);
	}
	printf("\n");
	//-----memcpy_s_Test_End-----------------------------

	return 0;
}