STL 小白学习（2） string

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

 //初始化操作
 void test01() {
     //初始化操作
     string s1;
     string s2(, 'a');
     string s3("abc");
     string s4(s3);

     cout << s1 << endl;
     cout << s2 << endl;
     cout << s3 << endl;
     cout << s4 << endl;

 }
 //赋值操作
 void test02() {
     //赋值操作
     string s1;
     string s2("appasd");
     s1 = "";
     cout << s1 << endl;
     s1 = s2;
     cout << s1 << endl;
     s1 = 'a';
     cout << s1 << endl;

     //成员方法 assign
     s1.assign("jsk");
     cout << s1 << endl;

 }

 //取值操作
 void test03() {
     //取值操作
     string s1 = "abashjdsa";

     //重载[]操作符
     for (int i = ; i < s1.size(); i++) {
         cout << s1[i] << " ";
     }
     cout << endl;

     //也提供了成员方法
     for (int i = ; i < s1.size(); i++) {
         cout << s1.at(i) << " ";
     }
     cout << endl;

     //区别
     //[] 访问越界直接挂
     //at(i) 抛出异常
     try {
         cout << s1.at()<<endl;
     }
     catch (...) {
         cout << "越界 Error...！" << endl;
     }

 }
 //拼接操作
 void test04() {
     //+= 重载
     string s = "";
     cout << s << endl;
     s += "";
     cout << s << endl;
     string s2 = "abc";
     s += s2;
     cout << s << endl;
     //append 成员函数重载
     string s3 = "";
     s.append(s3);
     cout << s << endl;
     //等号重载
     string s4 = s + s3;
     cout << s4 << endl;

 }

 //string 查找与替换
 void test05() {
     string s = "fgabcdefg";
     //s.find 查找第一次出现的位置
     int pos = s.find("z");
     cout << "pos: " << pos << endl;//没有 return -1
     //s.rfind 查找最后一次出现的位置
     pos = s.rfind('g');
     cout << "pos: " << pos << endl;

 }
 //替换
 void test06() {
     //替换
     string s = "abcdefg";
     s.replace(, , ""); //将0位置开始的2个 ab替换成1111
     cout << s << endl;
 }
 //比较
 void test07() {
     //比较 相等返回0
     string s1 = "abcd";
     string s2 = "abc4";

     if (s1.compare(s2) == ) {
         cout << "相等" << endl;
     }
     else {
         cout << "不相等！" << endl;
     }

 }
 //字串操作
 void test08() {
     string s = "abcsdsfsadas";
     string substring = s.substr(, );//取s的从1位置开始的3个字符的字串
     cout << substring << endl;

 }
 //插入 删除
 void test09() {
     string s = "asfasddfsa";
     s.insert(, "");//在s[1]位置前插入123
     cout << s << endl;
     s = "";
     s.erase(, );//删除 s[0]开始的4个字符
     cout << s << endl;
 }
 int main() {
     test09();
 }