字符串的反转五种方法

#include<iostream>
#include<string>
using namespace std;

char *reverse1(  char *str, int len)
{
if(len<=1)       //边界条件
return str;
char temp = *str;
*str = *(str+len-1);
*(str+len-1) = temp;
return (reverse1( str+1, len-2)-1);
}

char *reverse2( const char *str)
{
char *temp = new char[strlen(str)+1];
strcpy(temp, str);    //会复制\0
int len = strlen(str);
for( int i=0; i<len/2; i++)
{
char ch = temp[i];
temp[i] = temp[len-i-1];
temp[len-i-1] = ch;
}
//	temp[len] = '\0';
return temp;
}

char *reverse3( const char *str)
{
char *temp = new char[strlen(str)+1];
strcpy(temp, str);
int len = strlen(str);
char *head = temp;
char *rear = temp+len-1;
while(head<rear)
{
char ch = *head;
*head = *rear;
*rear = ch;
++head;
--rear;
}
//	temp[len] = '\0';
return temp;
}

char *reverse4( const char *str)
{
char *temp = new char[strlen(str)+1];
strcpy(temp, str);
int len = strlen(str);
char *head = temp;
char *rear = temp+len-1;
while(head<rear)
{
*head = *head+*rear;
*rear = *head-*rear;
*head = *head-*rear;
++head;
--rear;
}
return temp;
}

char *reverse5( const char *str)
{
char *temp = new char[strlen(str)+1];
strcpy(temp, str);
int len = strlen(str);
char *head = temp;
char *rear = temp+len-1;
while(head<rear)
{
*head^=*rear;
*rear^=*head;
*head^=*rear;
++head;
--rear;
}
return temp;
}
int main()
{
char str[7] = "123456";
cout<<reverse2(str)<<endl;
cout<<reverse3(str)<<endl;
cout<<reverse4(str)<<endl;
cout<<reverse5(str)<<endl;
cout<<reverse1(str, 6)<<endl;
return 0;
}