34.【C/C++ string大汇总，不看定后悔】（二）

#include <iostream>
using namespace std;
#include <string>
int main()
{
 string s = "abcd";
 if (s.empty())
 {
  cout << "该字符串为空" << endl;
 }
 else
 {
  cout << "该字符串不为空" << endl;
 }
 return 0;
}

#include <iostream>
using namespace std;
#include <string>
int main()
{
 string s = "abcd";
 s.clear(); // 对字符串进行清空处理
 if (s.empty())
 {
  cout << "该字符串为空" << endl;
 }
 else
 {
  cout << "该字符串不为空" << endl;
 }
 return 0;
}

#include <iostream>
using namespace std;
#include <string>
int main()
{
 string s1 = "hello";
 s1.at(0); // at()函数
 cout << "字符串s1的地1个是多少:" << s1.at(0) << endl;
 return 0;
}

#include <iostream>
#include <string.h>
using namespace std;
int main()
{
 string s1,s2,s4,s5,s6,s7,s8;
 int s3;
 s1 = "hello cctv.com byebye";
 cout << "原数组为:" << s1 << endl;
 s2=s1.substr(6, 8); // 从第几个开始，进行提取几个，
 cout <<"通过数数得:"<< s2 << endl;
 s3 = s1.find("cctv.com",0); // 找谁， 从第几个元素找
 s4 = s1.substr(s3, 8);
 cout <<"通过找到得:"<< s4 << endl;
 s5 = s1.replace(0, 5, "李威涛"); //从第几个开始，前几个字符换成后面的 
 cout << "通过replace进行添加:" << s5 << endl;
 s6 = s1.insert(0, "勇敢的"); //第几个开始 ，插入谁
 cout << "通过插入进行添加:" << s6 << endl;
 s7 = s1.insert(0, 3, 'v'); // 第几个开始，插入几个，插入谁
 cout << "插入字符为:" << s7 << endl;
 s1 = s1 + " 888";
 cout << s1 << endl;
 s8 = s1.erase(0, 5); //第几个开始， 删除几个
  cout << "删除:" << s8 << endl;
}