c++ - c ++字符串查找第一个非问题

Question

嗨，我想将字符从一点打印到另一点，例如

string str = "what is o and o this "; //I want to print all the 
                        //characters [ O and O ]
string temp1;
int loc1, loc2;
loc1 = str.find_first_not_of('o');
loc2 = str.find_last_not_of('o');
temp1 = str.substr(loc1, loc2);
cout << temp1 << endl; //this prints out entire string

谁能帮我？？谢谢大家的帮助！！

Answer 1

您应该使用find_first_of/find_last_of函数和substr期望长度的第二个参数，而不是位置：

string str = "what is o and o this "; //I want to print all the 
                        //characters [ O and O ]
string temp1;
int loc1, loc2;
loc1 = str.find_first_of('o');
if( loc1 == string::npos ) return; // symbol not found
loc2 = str.find_last_of('o');
temp1 = str.substr( loc1, loc2 - loc1 + 1 );
cout << temp1 << endl; //this prints out entire string