Programmer interview golden code interview question 01.01. determine whether the character is unique

Here is bool Array methods

#include <iostream>
#include<string>
using namespace std;
class Solution {
    
public:
	bool isUnique(string astr) {
    
		bool charRecord[100] = {
     false };// All use false To initialize 
		for (int i = 0; i<int(astr.length()); i++){
    
			if (charRecord[astr[i] - 'a'] == true)
				return false;
			else
				charRecord[astr[i] - 'a'] = true;
		}
		return true;
	}
};
void main(){
    
	string a = "aa"; //C++ Much stricter , Double quotes represent strings 、 Single quotation marks indicate the character 
	Solution object_f;
	bool b = object_f.isUnique(a);
	cout << b << endl;
}

The method of bit operation takes less memory . First write the main content , Layer upon layer , Or you'll forget .