Conditional statements in PHP are used to perform different
actions based on different conditions.
Conditional Statements
Very often when you write code, you want to perform different actions for
different decisions. You can use conditional statements in your code to do this.
In PHP we have two conditional statements:
- if (...else) statement - use this statement if you want to execute
a set of code when a condition is true (and another if the condition is not
true)
- switch statement - use this statement if you want to select one of
many sets of lines to execute
The If Statement
If you want to execute some code if a condition is true and another code if a
condition is false, use the if....else statement.
Syntax
if (condition)
code to be executed if condition is true;
else
code to be executed if condition is false;
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Example
The following example will output "Have a nice weekend!" if the current day
is Friday, otherwise it will output "Have a nice day!":
<html>
<body>
<?php
$d=date("D");
if ($d=="Fri")
echo "Have a nice weekend!";
else
echo "Have a nice day!";
?>
</body>
</html>
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If more than one line should be executed when a condition is true, the
lines should be enclosed within curly braces:
<html>
<body>
<?php
$x=10;
if ($x==10)
{
echo "Hello<br />";
echo "Good morning<br />";
}
?>
</body>
</html>
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The Switch Statement
If you want to select one of many blocks
of code to be executed, use the Switch statement.
Syntax
switch (expression)
{
case label1:
code to be executed if expression = label1;
break;
case label2:
code to be executed if expression = label2;
break;
default:
code to be executed
if expression is different
from both label1 and label2;
}
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Example
This is how it works: First we have a single expression (most often a
variable), that is evaluated once. The value of the expression is then compared
with the values for each case in the structure. If there is a match, the block
of code associated with that case is executed. Use break to prevent the
code from running into the next case automatically. The default statement is
used if none of the cases are true.
<html>
<body>
<?php
switch ($x)
{
case 1:
echo "Number 1";
break;
case 2:
echo "Number 2";
break;
case 3:
echo "Number 3";
break;
default:
echo "No number between 1 and 3";
}
?>
</body>
</html>
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