//Some basic input type checker //by baptiste prunier #include #include #include using namespace std; bool str_to_double(const string& s, double& d); int main(){ string s; double d; getline(cin,s); if(s.size() == 1){ if(s[0] >= '0' && s[0] <= '9') cout << s << " is a digit" << endl; else{ if((s[0] >= 'a' && s[0] <= 'z') || (s[0] >= 'A' && s[0] <= 'Z')) cout << s << " is a letter" << endl; else cout << s << " is a character" << endl; } }else{ if(!str_to_double(s,d)){ if(d == (int)d) cout << s << " is an integer" << endl; else cout << s << " is a floating number" << endl; }else cout << s << " is a string" << endl; } return 0; } bool str_to_double(const string& s, double& d){ double res; bool error = false; bool dot = false; unsigned long i = 0; int dec = 1; int signe = 1; if(s[0] == '+' || s[0] == '-'){ if(s[0] == '-') signe = -1; ++i; } while(i < s.size() && !error){ if((s[i] == '.' || s[i] == ',') && !dot) dot = true; else if(s[i] >= '0' && s[i] <= '9'){ if(dot){ dec *= 10; res += 1.*(s[i] - '0')/dec; }else res = res*10 + s[i] - '0'; }else error = true; ++i; } if(!error) d = res; return error; }

Basic input type checker