Question

error C2664: 'swap' : cannot convert parameter 1 from 'char *' to 'class std::basic_string<char,st

error C2664: 'swap' : cannot convert parameter 1 from 'char *' to 'class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > *' Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast出错了，但是不知道怎么改~~求大神！！

#include <iostream>
#include <string>
using namespace std;
int main()
{ void swap(string * , string * ) ;
string str1=" " ;
string str2=" " ;
string str3=" " ;
char *p1=&str1[0],*p2=&str2[0],*p3=&str3[0];
cout<<"请输入3个字符串："<<endl;
gets(p1);
gets(p2);
gets(p3);
if(strcmp(p1,p2)>0) swap(p1,p2);
if(strcmp(p1,p3)>0) swap(p1,p3);
if(strcmp(p2,p3)>0) swap(p2,p3);
cout<<str1<<" "<<str2<<" "<<str3<<endl;
return 0;
}
void swap(string *s1,string *s2)
{string temp;
temp=*s1;
*s1=*s2;
*s2=temp;}

Answer 1

string不能这么用！
char *p1=str1.c_ctr(),*p2=str2.c_ctr,*p3=str3.c_ctr();

这段代码相当不堪，建议用c++的swap算法或 string的swap函数来实现。
#include <string>
#include <iostream>
using namespace std;
int main()
{
string name("这是先前的");
cout<<name<<endl;
string swapname("这是调换后的");
name.swap(swapname);
cout<<name<<endl;
return 0;
}