#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;
}
