// // EvilNum is a little program that tests if a given Integer is Evil or Odious. // // Created by Ronen Gil on 11/10/2018. // #include // cout, cin, endl. #include // string, to_string, stoi. using namespace std; string dec2Bin(long); long countOnes(string); bool isEvil(string); int main(int argc, const char * argv[]) { string input = " "; bool flag = false; long num, i; cout << "An Evil Number is a number that has an even number of \'1\'s in it's Binary representation." << endl; cout << "A number that is not Evil is Odious;" << endl; //cout << "More info at: https://en.wikipedia.org/wiki/Evil_number" << endl; cout << "Use this program to check if a Number is Evil or Odious." << endl; while (!flag || input == "0") // Let's make sure we have an integer greater then 0. This loop doesn't work in this playground!! Enter Integers only! { cout << "Enter a hole number greater then 0:" << endl; cin >> input; switch (input[0]) { // The first character. case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9': flag = true; break; default: flag = false; break; } for (i = 1; i < input.size(); i++) // a loop to iterate the hole input. { if (flag) // Only if the characters before are all digits { switch (input[i]) { // The rest of the input. case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9': flag = true; break; default: flag = false; break; } } } if (!flag || input == "0") // there is a character in the input that is not a digit, or the input is "0". { cout << endl << input << " is NOT a hole number greater then 0!" << endl; } } num = stoi(input); // We have an integer. cout << endl << endl << num; isEvil(dec2Bin(num)) ? cout << " is an Evil Number!" << endl : cout << " is an Odious Number!" << endl; cout << "The Binary representation of " << num << " is: " << dec2Bin(num) << endl; cout << "The number of \'1\'s in it is: " << countOnes(dec2Bin(num)); cout << endl; return 0; } string dec2Bin(long dec) // Converts an Integer to a Binary string. { string bin = ""; while (dec > 0) { bin = to_string(dec % 2) + bin; dec /= 2; } return bin; } long countOnes(string bin) // Counts '1's in a Binary string. { long countOfOnes = 0, i; for (i = 0; i < bin.size(); i++) { if (bin[i] == '1') countOfOnes ++; } return countOfOnes; } bool isEvil(string bin) // Tests is a Binary string is Evil or Odious. { bool isevil; (countOnes(bin) % 2) == 0 ? isevil = true : isevil = false; return isevil; }

Evil Numbers.cpp