string.length() 的类型

 1 #include<iostream>
 2 #include<string>
 3 using namespace std;
 4 
 5 int main()
 6 {
 7     string s = "qwertyui";
 8     // cout << typeid(s.length()).name() << endl;
 9 
10     for (int p = 0; p < 10; p++)
11     {
12         if (p - s.length() >= 0)
13         {
14             cout << p << " ";
15         }
16     }
17     cout << endl;
18     system("pause");
19     return 0;
20 }

if (p >= s.length())