1     bool is_empty(const string &s) { return s.empty(); }

 1 bool have_upper(const string &s)
 2 {
 3     for (auto c : s)
 4     {
 5         if (isupper(c))
 6             return true;
 7     }
 8     return false;
 9 }
10 
11 void to_lower(string &s)
12 {
13     for (auto &c : s)
14     {
15         if (isupper(c))
16             c = tolower(c);
17     }
18 }
19 
20 int main()
21 {
22     string str{ "Hello World" };
23     bool a = have_upper(str);
24     cout << a << endl;
25     to_lower(str);
26     cout << str << endl;
27     system("pause");
28     return 0;
29 }