freeCodeCamp/guide/english/cplusplus/the-if-statement/index.md

title
C++ If Statement

The IF statement.

What does an if statement do?

• The if statement evaluates the test expression present inside the parenthesis.

• The if statement uses relational and logical operators to make logical expressions.

  ---

  The general form of if statement:

  if (Test Expression / Condition)
  {
    // Block of statements if test expression is True
  }

If there is only one statement after the if statement the '{ }' are not necessarily required . But if there are more number of statements after if statement, then it is mandatory to put all those statements in '{}'.

If the value of the test expression is true, then the block of code inside the if statement is executed.

If the value of the test expression is false, then the block of code inside the if statement is skipped and your code continues.

Example if statement:

  int a = 10;
  
  // true statement
  if (a < 20)
  {
    // execute this block of code
  }

  // false statement
  if (a < 0)
  {
    // Skip this block of code.
  }

Example In C++ :

  // Program to check if number entered by the user is positive
  // If negative, the block of code is skipped

  #include <iostream>
  using namespace std;

  int main()
  {
    int no ;
    cout << "Enter a number: ";
    cin >> no;

    // if statement to check if the number is positive
    if ( no > 0)
    {
      cout << "You have entered a positive number: " << no << endl;
    }

    // If number is not positive, then if statement is skipped a program continues
    cout << "This step is always printed" << endl;

    return 0;
  }

Output:

OUTPUT 1:

Enter a number: 5
You have entered a positive number: 5
This step is always printed 

This is the output when the number entered is positive.

OUTPUT 2:

Enter a number:  -1
This step is always printed

This is the output when the number entered is negative.

Try the code yourself ! :)

CONGRATULATIONS . This is the end of the article on the IF statement

Good Luck to all of you

Happy Coding ! :)

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