string&vector阅读小测试

来源：互联网发布：淘宝怎么测图编辑：程序博客网时间：2024/04/29 05:29

看c++ primer，测试了几条语法，保存一下代码~
1.初始化string
注：字符串字面量不能直接相加

#include "stdafx.h"#include <string>#include <iostream>using namespace std;int main(){    string f5(5, 'f');    string g5(5, 'g');    //string test="hello"+"!"; 错误！字符串字面量不能直接相加    string str1 = f5 + g5;    string str2(g5 + f5);    if (str1 > str2)        cout << str1;    else        cout << str2;    system("pause");    return 0;}

2.修改string中的值

#include "stdafx.h"#include <string>#include <iostream>using namespace std;int main(){    string str("abc abc");    for (decltype(str.size()) i = 0; i < str.size() &&        !isspace(str[i]); i++)        str[i] = toupper(str[i]);    //运用range for语句改变str中的值时，记得把定义的变量设置为引用，否则无用    for (auto &c : str){        c = tolower(c);    }    for (auto c : str){        cout << c << " ";    }    system("pause");    return 0;}

3.初始化vector

#include "stdafx.h"#include <iostream>#include <vector>using namespace std;typedef vector<int> vint;typedef vector<char> vchar;int main(){    vint v{ 1, 2, 3 }; //输出1 2 3    vint v1(10); //输出0 0 0...    vint v2{ 10 };//输出10    vint v3(10, -1);//输出-1 -1 -1...    vint v4{ 10, -1 };//输出10 -1    vchar vc{ 'a' ,'b','c'};//输出a b c    vint v5;    for (int i = 0; i < 5; i++)        v5.push_back(i);//输出0 1 2 3 4    vint v6(5);//v6已经压入5个0    for (int i = 0; i < 5; i++)        v6.push_back(5);//输出0 0 0 0 0 5 5 5 5 5    v5 = { 9, 9, 9 };//v5输出9 9 9    v6 = v5;//v6输出9 9 9    vint v7;    /*v7为空，此声明严重错误，程序会崩    for (int i = 0; i < 5; i++){        v7[i] = i;    }*/    for (int t; cin>>t;v7.push_back(t));//自行初始化，ctrl+Z结束    for (auto c : v7)        cout << c << endl;    //使用迭代器访问，迭代器和!=是良配    for (auto it = v7.begin(); it != v7.end(); ++it)        cout << *it << " ";    system("pause");    return 0;}

阅读全文

0 0