学步园

本机windows系统安装了VS2008环境下，查看xstring文件的源码发现xstring类的c_str(),data()实现如下

	const _Elem *__CLR_OR_THIS_CALL c_str() const
		{	// return pointer to null-terminated nonmutable array
		return (_Myptr());
		}

	const _Elem *__CLR_OR_THIS_CALL data() const
		{	// return pointer to nonmutable array
		return (c_str());
		}

这难道有区别吗？？？

写了个测试代码如下：

#include<stdio.h>
#include<cstring>
#include<string>
using std::string;

int _tmain(int argc, _TCHAR* argv[])
{
	sTopic = "hello world";
	const char* pC_str = sTopic.c_str();
	printf("sTopic.c_str()=%d, sizeof(...)=%d, strlen(...)=%d\n", pC_str, sizeof(sTopic.c_str()), strlen(pC_str) );
	const char* pData = sTopic.data();
	printf("sTopic.data()=%d, sizeof(...)=%d, strlen(...)=%d\n", pData, sizeof(sTopic.data()), strlen(pData) );
	char * pTemp = const_cast<char*>(sTopic.c_str() );
	pTemp[0] = 'a'; 
	printf("modify [0]='a' after const_cast(sTopic.c_str() ) sTopic=%s\n", sTopic.c_str() );
	pTemp = const_cast<char*>(sTopic.data() );
	pTemp[1] = 'b';
	printf("modify [1]='b' after const_cast(sTopic.data() ) sTopic=%s\n", sTopic.c_str() );
	return 0;
}

结果是：

sTopic.c_str()=23859240, sizeof(...)=4, strlen(...)=11
sTopic.data()=23859240, sizeof(...)=4, strlen(...)=11
modify [0]='a' after const_cast(sTopic.c_str() ) sTopic=aello world
modify [1]='b' after const_cast(sTopic.data() ) sTopic=abllo world