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

自己写一个具有strcat函数功能的函数

实现代码如下：

#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

使用strlen()函数求数组的大小，strcat()函数用来连接字符串

实现代码如下：

#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;	
}