C++的string容器-＞基本概念、构造函数、赋值操作、字符串拼接、查找和替换、字符串比较、字符存取、插入和删除、子串

#include<iostream>

using namespace std;

#include <string>

//string的构造函数

/*

-string(); //创建一个空的字符串 例如: string str;

-string(const char* s); //使用字符串s初始化

-string(const string& str); //使用一个string对象初始化另一个string对象

-string(int n, char c); //使用n个字符c初始化

*/

void test01()

{

string s1; //默认构造，创建空字符串，调用无参构造函数

cout << "str1 = " << s1 << endl;

const char* str = "hello world";

string s2(str); //把c_string转换成了string

cout << "s2 = " << s2 << endl;

string s3(s2); //调用拷贝构造函数

cout << "s3 = " << s3 << endl;

string s4(10, 'a');

cout << "s4 = " << s4 << endl;

}

int main()

{

test01();

system("pause");

return 0;

}

#include<iostream>

using namespace std;

#include <string>

//string赋值操作

/*

* string& operator=(const char* s); //char*类型字符串 赋值给当前的字符串

* string& operator=(const string &s); //把字符串s赋给当前的字符串

* string& operator=(char c); //字符赋值给当前的字符串

* string& assign(const char *s); //把字符串s赋给当前的字符串

* string& assign(const char *s, int n); //把字符串s的前n个字符赋给当前的字符串

* string& assign(const string &s); //把字符串s赋给当前字符串

* string& assign(int n, char c); //用n个字符c赋给当前字符串

*/

void test01()

{

string str1;

str1 = "hello world";

cout << "str1 = " << str1 << endl;

string str2;

str2 = str1;

cout << "str2 = " << str2 << endl;

string str3;

str3 = 'a';

cout << "str3 = " << str3 << endl;

string str4;

str4.assign("hello c++");

cout << "str4 = " << str4 << endl;

string str5;

str5.assign("hello c++",5);

cout << "str5 = " << str5 << endl;

string str6;

str6.assign(str5);

cout << "str6 = " << str6 << endl;

string str7;

str7.assign(5, 'x');

cout << "str7 = " << str7 << endl;

}

int main()

{

test01();

system("pause");

return 0;

}

#include<iostream>

using namespace std;

#include <string>

//string字符串拼接

/*

* string& operator+=(const char* str); //重载+=操作符

* string& operator+=(const char c); //重载+=操作符

* string& operator+=(const string& str); //重载+=操作符

* string& append(const char *s); //把字符串s连接到当前字符串结尾

* 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

* string& append(const string &s); //同operator+=(const string& str)

* 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

*/

void test01()

{

string str1 = "我";

str1 += "爱玩游戏";

cout << "str1 = " << str1 << endl;

str1 += ':';

cout << "str1 = " << str1 << endl;

string str2 = "LOL DNF";

str1 += str2;

cout << "str1 = " << str1 << endl;

string str3 = "I";

str3.append(" love ");

str3.append("game abcde", 4);

//str3.append(str2);

str3.append(str2, 4, 3); // 从下标4位置开始 ，截取3个字符，拼接到字符串末尾

cout << "str3 = " << str3 << endl;

}

int main()

{

test01();

system("pause");

return 0;

}

#include<iostream>

using namespace std;

#include <string>

//string查找和替换

/*

* int find(const string& str, int pos = 0) const; //查找str第一次出现位置,从pos开始查找

* int find(const char* s, int pos = 0) const; //查找s第一次出现位置,从pos开始查找

* 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

* int find(const char c, int pos = 0) const; //查找字符c第一次出现位置

* int rfind(const string& str, int pos = npos) const; //查找str最后一次位置,从pos开始查找

* int rfind(const char* s, int pos = npos) const; //查找s最后一次出现位置,从pos开始查找

* 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

* int rfind(const char c, int pos = 0) const; //查找字符c最后一次出现位置

* string& replace(int pos, int n, const string& str); //替换从pos开始n个字符为字符串str

* string& replace(int pos, int n,const char* s); //替换从pos开始的n个字符为字符串s

*/

void test01()

{

//1.查找

string str1 = "abcdefgde";

int pos = str1.find("de");

if (pos == -1)

{

cout << "未找到" << endl;

}

else

{

cout << "pos = " << pos << endl;

}

//rfind和find区别

//rfind从右往左查找 find从左往右查找

pos = str1.rfind("de");

cout << "pos = " << pos << endl;

}

void test02()

{

//2.替换

string str1 = "abcdefgde";

//从1号位置起 3个字符 替换为"1111"

str1.replace(1, 3, "1111");

cout << "str1 = " << str1 << endl;

}

int main()

{

test01();

test02();

system("pause");

return 0;

}

#include<iostream>

using namespace std;

#include <string>

//字符串比较

void test01()

{

string s1 = "hello";

string s2 = "aello";

int ret = s1.compare(s2);

if (ret == 0)

{

cout << "s1 等于 s2" << endl;

}

else if (ret > 0)

{

cout << "s1 大于 s2" << endl;

}

else

{

cout << "s1 小于 s2" << endl;

}

}

int main()

{

test01();

system("pause");

return 0;

}

#include<iostream>

using namespace std;

#include <string>

//string字符存取

void test01()

{

string str = "hello world";

//1.通过[]访问单个字符

for (int i = 0; i < str.size(); i++)

{

cout << str[i] << " ";

}

cout << endl;

//2.通过at方式访问单个字符

for (int i = 0; i < str.size(); i++)

{

cout << str.at(i) << " ";

}

cout << endl;

//修改单个字符

str[0] = 'x';

str.at(1) = 'x';

cout << str << endl;

}

int main()

{

test01();

system("pause");

return 0;

}

#include<iostream>

using namespace std;

#include <string>

//字符串插入和删除

void test01()

{

string str = "hello";

//插入

str.insert(1, "111");

cout << str << endl;

//删除

str.erase(1, 3); //从1号位置开始3个字符

cout << str << endl;

}

int main()

{

test01();

system("pause");

return 0;

}

#include<iostream>

using namespace std;

#include <string>

//string求子串

void test01()

{

string str = "abcdefg";

string subStr = str.substr(1, 3);

cout << "subStr = " << subStr << endl;

//实用操作

string email = "hello@sina.com";

int pos = email.find("@");

string username = email.substr(0, pos);

cout << "username: " << username << endl;

}

int main()

{

test01();

system("pause");

return 0;

}