# if

## Description

The if statement checks for a condition and executes the proceeding statement or set of statements if the condition is 'true'.

## Syntax

if (condition) { //statement(s) }

## Parameter Values

• condition: a boolean expression (i.e., can be true or false).

## Example Code

The brackets may be omitted after an if statement. If this is done, the next line (defined by the semicolon) becomes the only conditional statement.

if (x > 120) digitalWrite(LEDpin, HIGH); if (x > 120) digitalWrite(LEDpin, HIGH); if (x > 120) {digitalWrite(LEDpin, HIGH);} if (x > 120) { digitalWrite(LEDpin1, HIGH); digitalWrite(LEDpin2, HIGH); } // all are correct

※ NOTES AND WARNINGS:

The statements being evaluated inside the parentheses require the use of one or more operators shown below.

### Comparison Operators:

x == y (x is equal to y) x != y (x is not equal to y) x < y (x is less than y) x > y (x is greater than y) x <= y (x is less than or equal to y) x >= y (x is greater than or equal to y)

Beware of accidentally using the single equal sign (e.g. if (x = 10) ). The single equal sign is the assignment operator, and sets x to 10 (puts the value 10 into the variable x). Instead use the double equal sign (e.g. if (x == 10) ), which is the comparison operator, and tests whether x is equal to 10 or not. The latter statement is only true if x equals 10, but the former statement will always be true.

This is because C++ evaluates the statement if (x=10) as follows: 10 is assigned to x (remember that the single equal sign is the (assignment operator)), so x now contains 10. Then the 'if' conditional evaluates 10, which always evaluates to TRUE, since any non-zero number evaluates to TRUE. Consequently, if (x = 10) will always evaluate to TRUE, which is not the desired result when using an 'if' statement. Additionally, the variable x will be set to 10, which is also not a desired action.