编写一程序，将两个字符串连接起来的3种方法

1.用字符数组和自己书写的函数实现

#include<iostream>
using namespace std;
int main(){
char a[100],b[50];
void Strcat(char a[],char b[]);
cout<<"please input first string:"<<endl;
cin>>a;
cout<<"please input second string:"<<endl;
cin>>b;
Strcat(a,b);
cout<<"The new string: "<<a;
cout<<endl;
return 0;
}
void Strcat(char a[],char b[]){
int i,j;
for(i=0;a[i]!='\0';i++);
cout<<"Length of first string:"<<i<<endl;
for(j=0;b[j]!='\0';j++,i++){
a[i]=b[j];
}
cout<<"Length of second string:"<<j<<endl;
}

2.用标准库中的strcat函数

#include<iostream>
#include<string>
using namespace std;
int main(){
char a[100],b[50];
cout<<"please input first string:"<<endl;
cin>>a;
cout<<"please input second string:"<<endl;
cin>>b;
cout<<"Length of first string :"<<strlen(a)<<endl;
cout<<"Length of first string :"<<strlen(b)<<endl;
cout<<"The new string: "<<strcat(a,b);
cout<<endl;
return 0;
}

3.用string方法定义字符串变量

#include<iostream>
#include<string>
using namespace std;
int main(){
string a,b;
cout<<"please input first string:"<<endl;
cin>>a;
cout<<"please input second string:"<<endl;
cin>>b;
cout<<"New string :"<<(a+b)<<endl;
return 0;
}