PHP Decision
Making
The if,
elseif ...else and switch statements are used to take
decision based on the different condition.
You can use conditional statements in your code to
make your decisions. PHP supports following three decision making 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
·
elseif statement −
is used with the if...else statement to execute a set of code if one of
the several condition is true
·
switch statement −
is used if you want to select one of many blocks of code to be executed, use
the Switch statement. The switch statement is used to avoid long blocks of if..elseif..else
code.
The If...Else
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;
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>
It will produce the following result −
The ElseIf Statement
If you want to execute some code if one of the
several conditions are true use the elseif statement
Syntax
if (condition)
code to
be executed if condition is true;
elseif (condition)
code to
be executed if condition is true;
else
code to
be executed if condition is false;
Example
The following example will output "Have a nice
weekend!" if the current day is Friday, and "Have a nice
Sunday!" if the current day is Sunday. Otherwise, it will output
"Have a nice day!" −
<html>
<body>
<?php
$d = date("D");
if ($d == "Fri")
echo "Have a nice weekend!";
elseif
($d == "Sun")
echo "Have a nice Sunday!";
else
echo "Have a nice day!";
?>
</body>
</html>
It will produce the following result −
The Switch
Statement
If you want to select one of many blocks of code to
be executed, use the Switch statement.
The switch statement is used to avoid long blocks
of if..elseif..else code.
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;
}
Example
The switch statement works in an
unusual way. First it evaluates given expression then seeks a lable to match the resulting value. If a matching value is
found then the code associated with the matching label will be executed or if
none of the lable matches then statement will execute
any specified default code.
<html>
<body>
<?php
$d = date("D");
switch ($d){
case "Mon":
echo "Today is Monday";
break;
case "Tue":
echo "Today is Tuesday";
break;
case "Wed":
echo "Today is Wednesday";
break;
case "Thu":
echo "Today is Thursday";
break;
case "Fri":
echo "Today is Friday";
break;
case "Sat":
echo "Today is Saturday";
break;
case "Sun":
echo "Today is Sunday";
break;
default:
echo "Wonder which day is this ?";
}
?>
</body>
</html>
It will produce the following result −
Today is Monday