C ++ STL（标准模板库）中的std :: string
字符串作为数据类型
在C语言中，我们知道字符串基本上是一个以\0结尾的字符数组。因此，要对字符串进行操作，我们定义了字符数组。但是在C++中，标准库为我们提供了将字符串用作基本数据类型（如整数）的便利。
示例
Like we define and declare,
int i=5;
Same way, we can do for a string like,
String s= "NHOOO";请记住，需要在“”下定义一个字符串变量（文字）。“a”是字符，而“a”是字符串。
可以对字符串执行的基本操作
访问字符串字符
返回字符串大小
相比
级联
需要的头文件：
#include <string>
Or
#include <bits/stdc++.h>C++程序演示std::string的示例
#include <bits/stdc++.h>
using namespace std;
int main(){
string s;
//reading & printing
cout<<"Enter your string\n";
cin>>s;
cout<<"Sting you entered is: "<<s<<endl;
//打印尺寸/长度
cout<<"length of the "<<s<<" is = "<<s.length()<<endl;
//添加两个字符串
string s1="Include";
string s2="Help";
cout<<"s1+s2: "<<s1+s2<<endl;
//比较
if(s1==s2)
cout<<s1<<" and "<<s2<<" are equal"<<endl;
else
cout<<s1<<" and "<<s2<<" are not equal"<<endl;
//访问字符
cout<<"character at 0 index in "<<s<<" is = "<<s[0]<<endl;
cout<<"character at 1 index in "<<s<<" is = "<<s[1]<<endl;
cout<<"character at 5 index in "<<s<<" is = "<<s[5]<<endl;
return 0;
}输出结果
Enter your string NHOOO Sting you entered is: NHOOO length of the NHOOO is = 11 s1+s2: NHOOO Include and Help are not equal character at 0 index in NHOOO is = I character at 1 index in NHOOO is = n character at 5 index in NHOOO is = d