[Programmers] 문자열 다루기 기본

bool solution(string s) {
    int size = s.size();
    bool answer = true;
    if(size != 4 && size != 6)
        answer = false;
    else{
        for(int i=0; i<size; i++){
            if(  s[i] == '0' || s[i] == '1' || s[i] == '2' || s[i] == '3' || s[i] == '4' || s[i] == '5' || s[i] == '6' || s[i] == '7' || s[i] == '8' || s[i] == '9' ){
                continue;
            }else{
                answer = false;
                break;
            }
        }
    }
    return answer;
}

bool solution(string s) {
    if (s.length() != 4 && s.length() != 6)
        return false;
    for (int i = 0; i < s.length(); i++) {
        if (s[i] < 48 || s[i] > 57)
            return false;
    }
    return true;
}