1   //method 1: the constructor of string()
2     char c = 'F';
3     string s = string(1, c);
4     cout << s ;

1  //method 2: stringstream
2     char c1 = 'F';
3     stringstream ss;
4     ss << c1;
5     string s2;
6     ss >> s2;
7     cout << s2;

1     //method 3: sprintf()
2     char c2 = 'F';
3     char s3[] ={};
4     sprintf(s3, "%c", c2);
5     string s4 = string(s3);
6     cout << s4;