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if-else conditional statement

Availability

PHP 4, PHP 5, PHP 7, PHP 8

Usage

Often you’d want to execute a statement if a certain condition is met, and a different statement if the condition is not met. This is what else is for. else extends an if statement to execute a statement in case the expression in the if statement evaluates to false. For example, the following code would display a is greater than b if $a is greater than $b, and a is NOT greater than b otherwise:

<?php
if ($a > $b) {
  echo "a is greater than b";
} else {
  echo "a is NOT greater than b";
}
?>

The else statement is only executed if the if expression evaluated to false, and if there were any elseif expressions - only if they evaluated to false as well.

Note: Dangling else

In case of nested if - else statements, an else is always associated with the nearest if.

<?php
$a = false;
$b = true;
if ($a)
    if ($b)
        echo "b";
else
    echo "c";
?>

Despite the indentation (which does not matter for PHP), the else is associated with the if ($b), so the example does not produce any output. While relying on this behavior is valid, it is recommended to avoid it by using curly braces to resolve potential ambiguities.

– PHP Reference

Example

<?php

if (1 > 2)
  print("1 > 2\n");
else
  print("!(1 > 2)\n");

if (2 > 1)
  print("2 > 1\n");
else
  print("!(2 > 1)\n");

View: Example

Execute:

Result:

!(1 > 2)
2 > 1

Alternative syntax

The following example shows the shortened form for HTML templates.

<?php

if (1 > 2):
  print("1 > 2\n");
else:
  print("!(1 > 2)\n");
endif;

if (2 > 1):
  print("2 > 1\n");
else:
  print("!(2 > 1)\n");
endif;

View: Example

Execute:

Result:

!(1 > 2)
2 > 1

Formatting

The following example shows the all possible formating of the statement (but not all are compliant with the official PHP formatting standards).

<?php

$condition = (1 > 2);

if ($condition)
  print("1 > 2\n");
else
  print("!(1 > 2)\n");

$condition = (2 > 1);

if ($condition)
  print("2 > 1\n");
else
  print("!(2 > 1)\n");

print("\n");

if (1 > 2)
  print("1 > 2\n");
else
  print("!(1 > 2)\n");

if (2 > 1)
  print("2 > 1\n");
else
  print("!(2 > 1)\n");

print("\n");

if (1 > 2) print("1 > 2\n");
else print("!(1 > 2)\n");

if (2 > 1) print("2 > 1\n");
else print("!(2 > 1)\n");

print("\n");

if (1 > 2) {
  print("1 > 2\n");
} else {
  print("!(1 > 2)\n");
}

if (2 > 1) {
  print("2 > 1\n");
} else {
  print("!(2 > 1)\n");
}

print("\n");

// Shortened form for HTML templates:

if (1 > 2):
  print("1 > 2\n");
else:
  print("!(1 > 2)\n");
endif;

if (2 > 1):
  print("2 > 1\n");
else:
  print("!(2 > 1)\n");
endif;

print("\n");

if (1 > 2):  print("1 > 2\n");
else: print("!(1 > 2)\n"); endif;

if (2 > 1):  print("2 > 1\n");
else: print("!(2 > 1)\n"); endif;

print("\n");

View: Example

Execute:

Result:

!(1 > 2)
2 > 1

!(1 > 2)
2 > 1

!(1 > 2)
2 > 1

!(1 > 2)
2 > 1

!(1 > 2)
2 > 1

!(1 > 2)
2 > 1

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