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
several condition are 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.
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.
|
if (condition)
code
to be executed if condition is true;
else
code
to be executed if condition is false;
|
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>
|
If more than one line
should be executed if a condition is true/false, the lines should be enclosed
within curly braces:
|
<html>
<body>
<?php
$d=date("D");
if ($d=="Fri")
{
echo
"Hello!<br />";
echo
"Have a nice weekend!";
echo
"See you on Monday!";
}
?>
</body>
</html>
|
If you want to execute some
code if one of several conditions are true use the elseif statement
|
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;
|
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>
|
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.
|
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;
}
|
The switch statement
works in an unusual way. First it evaluates given expression then seeks a label
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 labels
match 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>
|
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