_id: “0143129a8d” title: string date: 2020-11-27 15:03 update: 2020-11-27 15:03 author: Rainboy video: “” titleEmojiTag: “:tv:”

string的使用

string版的hello world

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

int main(){
    string s1("hello world 1");
    cout << s1 <<endl;
    string s2 = "hello world 2";
    cout << s2 <<endl;
    string s3;
    s3 = "hello world 3";
    cout << s3 <<endl;
    s3 = "hello world 4";
    cout << s3 <<endl;
    return 0;
}

string对象的定义与初始化

string的读入

每一次读到一个空格停止

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

int main(){
    string s1;
    cin >> s1;
    cout << s1 << endl;
}

string的操作

常用操作

代码1

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

int main(){
    
    string s1;
    if( s1.empty())
        cout << "yes,empty"<<endl;
    //s1[1] ='c'; //下标操作：不能赋值给不存在的地方
    s1 = "new string str";//可以
    s1[1] ='c';//下标操作，ok
    return 0;
}

代码2

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

int main(){
    
    string s1(100,0);//初始化100个字符数值为0的字符串
    
    int i;
    for(i=0;i<100;i++)
        s1[i]= 'c';
    cout <<  s1 <<endl;
    
    string::size_type x;
    for(x=0;x<s1.size();x++)
        s1[x]='d';
    cout <<  s1 <<endl;

    return 0;
}

ps

string::size_type

表示的是一种无论string有多长,都能存个其长度的类型.

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

int main(){
    string::size_type len;
    string s1 = "hello world!";
    for(len=0;len<s1.size();len++)
        cout << s1[len] << endl;
    return 0;
}