---
title: if
categories: [ "Structure" ]
subCategories: [ "Control Structure" ]
---





= if


// OVERVIEW SECTION STARTS
[#overview]
--
[float]
=== Description
The `if` statement checks for a condition and executes the following statement or set of statements if the condition is 'true'.
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[float]
=== Syntax
[source,arduino]
----
if (condition) {
  //statement(s)
}
----


[float]
=== Parameters
`condition`: a boolean expression (i.e., can be `true` or `false`).

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// OVERVIEW SECTION ENDS




// HOW TO USE SECTION STARTS
[#howtouse]
--

[float]
=== 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.
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[source,arduino]
----
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
----
[%hardbreaks]


[float]
=== Notes and Warnings
The statements being evaluated inside the parentheses require the use of one or more operators shown below.
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*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 (http://arduino.cc/en/Reference/Assignment[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.
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// SEE ALSO SECTION BEGINS
[#see_also]
--

[float]
=== See also

[role="language"]
* #LANGUAGE# link:../else[else]

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// SEE ALSO SECTION ENDS