C++ Program to Check if a Number Is Positive Or Negative

Methods to Check Number Sign

Given an integer input, the objective is to check whether the given integer is Positive or Negative. In order to do so we have the following methods:

• Method 1: Using Brute Force

  Algorithm

  For a user input num:

  If the num > 0: it is a positive number.

  If the num < 0: it is a negative number.

  Else the number has to be zero itself

  #include <iostream>
  using namespace std;
  
  int main() {
      int num;
      cout << "Enter a number: ";
      cin >> num;
      
      if (num > 0)
          cout << "The number is Positive" << endl;
      else if (num < 0)
          cout << "The number is Negative" << endl;
      else
          cout << "The number is Zero" << endl;
  
      return 0;
  }

  Output:

  Enter a number: -3
  The number is Negative

• Method 2: Using Nested if-else Statements

  Algorithm

  1. Take input from the user

  2. If the number is greater than zero, print "Positive"

  3. Else, check if the number is less than zero

  4. If true, print "Negative"

  5. Otherwise, print "Zero"

  #include <iostream>
  using namespace std;
  
  int main() {
      int num;
      cout << "Enter a number: ";
      cin >> num;
      
      if (num >= 0) {
          if (num == 0)
              cout << "The number is Zero" << endl;
          else
              cout << "The number is Positive" << endl;
      } else {
          cout << "The number is Negative" << endl;
      }
  
      return 0;
  }

  Output:

  Enter a number: 0
  The number is Zero

• Method 3: Using the ternary operator

  Algorithm

  1. Take input from the user

  2. Use the ternary operator to check the number's sign

  3. Print the result accordingly

  #include <iostream>
  #include <string>
  using namespace std;
  
  int main() {
      int num;
      cout << "Enter a number: ";
      cin >> num;
  
      string result = (num > 0) ? "The number is Positive" : 
                     (num < 0) ? "The number is Negative" : 
                                 "The number is Zero";
      cout << result << endl;
  
      return 0;
  }

  Output:

  Enter a number: 5
  The number is Positive