C++学习笔记之string容器、vector容器

#include <iostream>
using namespace std;
#include <string>
//以下参数为const char* 类型与string类型的函数参数可以相互替换
void test01()
{
//一、string构造函数

string s1;//1.默认构造

const char* str1 = "max";
string s3(str1);//2.使用字符串进行初始化构造
cout << "s3 =" << s3 << endl;

string s4(s3);//3.使用一个string对象初始化另一个string对象
cout << "s4 =" <<s4 <<endl;

string s5(7, 'x');
cout << "s5=" <<s5<< endl;

//二.赋值方式
const char* str2 = "min";
s5 = str2;//char*类型字符串 赋值给当前的字符串
cout << "s5=" << s5 << endl;

s5 = s4;//把字符串s赋给当前的字符串
cout << "s5=" << s5 << endl;

s5 = 'a';//字符赋值给当前的字符串
cout << "s5=" << s5 << endl;

s5 = str2;//char*类型字符串 赋值给当前的字符串
s5 = "hello,world";
cout << "s5=" << s5 << endl;

s5.assign(str2);//把字符串s赋给当前的字符串
cout << "s5=" << s5 << endl;

s5.assign(str2,2);//把字符串s的前n个字符赋给当前的字符串
cout << "s5=" << s5 << endl;

s5.assign(s4);//把字符串s赋给当前字符串
cout << "s5=" << s5 << endl;

s5.assign(2, 's');//用n个字符c赋给当前字符串
cout << "s5=" << s5 << endl;

 //三、字符串拼接


s5 += "rr";//string& operator+=(const char* str);重载+=操作符
cout << "s5=" << s5 << endl;

s5 += 'a';//string& operator+=(const char c); //重载+=操作符
cout << "s5=" << s5 << endl;

s5 += s4;//string& operator+=(const string& str); //重载+=操作符
cout << "s5=" << s5 << endl;

string str11 = "I LOVE ";
    str11.append("my country");//string& append(const char *s); //把字符串s连接到当前字符串结尾
cout << "str11=" << str11 << endl;

str11.append("tooooo",2);//string& append(const char *s, int n); //把字符串s的前n个字符连接到当前字符串结尾
cout << "str11=" << str11 << endl;

string str12 = "1";
str11.append(str12);//string& append(const string &s); //同operator+=(const string& str)
cout << "str11=" << str11 << endl;

string str13 = "2223333";//string& append(const string &s, int pos, int n); //字符串s中从pos开始的n个字符连接到字符串结尾
str11.append(str13,3,3);
cout << "str11=" << str11 << endl;

//四、查找和替换

//find查找是从左往后，rfind从右往左;
// find找到字符串后返回查找的第一个字符位置，找不到返回-1;
// replace在替换时，要指定从哪个位置起，多少个字符，替换成什么样的字符串
string str111="yue shi gu xiang ming";
int pos1 = str111.find("ng");//int find(const string& str, int pos = 0) const;查找str第一次出现位置,从pos位置开始查找
cout << "pos1=" << pos1 << endl;
int pos4 = str111.find("ng",0,1);//int find(const char* s, int pos, int n) const; //从pos位置查找s的前n个字符第一次位置
cout << "pos4=" << pos4 << endl;
int pos2 = str111.rfind("ng"); //int rfind(const string& str, int pos = npos) const;查找str最后一次位置, 从pos开始查找
cout << "pos2=" << pos2 << endl;
int pos3 = str111.rfind("ng",21,1); //int rfind(const char* s, int pos, int n) const; //从pos查找s的前n个字符最后一次位置
cout << "pos3=" << pos3 << endl;

cout << "替换前str111=" << str111 << endl;
str111.replace(0,7,"moon is");//替换从pos开始n个字符为字符串str
cout << "替换后str111=" << str111 << endl;

//五、字符串比较

//字符串对比主要是用于比较两个字符串是否相等
string str555 = "hello";
string str556 = "hello";
int pos557=str555.compare(str556);//int compare(const string &s) const;返回值为0，二者相等
int pos558 = str555.compare("hello");//int compare(const char *s) const;
cout <<"pos557=" << pos557 << endl;
cout <<"pos558=" << pos558 << endl;

//六、字符串存取

//string字符串中单个字符存取有两种方式，利用 [ ] 或 at
string str666 = "hello world";
for (int i = 0; i < str666.size(); i++)
{
cout<<"str666=" << str666[i] << " ";
}
cout << endl;
for (int i = 0; i < str666.size(); i++)
{
cout<<"str666" << str666.at(i) << " ";
}
cout << endl;
//字符修改
str666[0] = 'x';
str666.at(1) = 'x';
cout <<"str666" << str666 << endl;

//七、字符串插入与删除
// 
//插入和删除的起始下标都是从0开始
string str777 = "hello world";
str777.insert(2,"llll"); //string& insert(int pos, const char* s); //插入字符串
cout << "str777=" << str777 << endl;

str777.insert(8, 3, 'x');//string& insert(int pos, int n, char c); //在指定位置插入n个字符c
cout << "str777=" << str777 << endl;

str777.erase(8,3);
str777.erase(2,4);//string& erase(int pos, int n = npos); //删除从Pos开始的n个字符
cout << "str777=" << str777 << endl;

//八、string子串
// 
//从字符串中获取想要的子串
string str888 = "hello world";
string str889=str888.substr(0, 5); //string substr(int pos = 0, int n = npos) const; //返回由pos开始的n个字符组成的字符串
cout << "str889=" << str889 << endl;
}
int main() {
test01();
}

2.vector容器