PHP Decision Making
and Looping:
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.
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>
The elseIf Statement
If you want to execute some code if one of several
conditions are true use the elseif statement
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=="Sat")
echo "Have a nice weekend!";
elseif
($d=="Sun")
echo "Have a nice Sunday!";
else
echo "Have a nice day!";
?>
</body>
</html>
The Switch Statement
If you want to select one of many blocks of code to be
executed, use the Switch statement.
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 lables match then statement will 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>
PHP Loop Types:
The for loop
statement
The for statement is used when you know how many times you
want to execute a statement or a block of statements.
Example
The following example makes five iterations and changes the
assigned value of two variables on each pass of the loop:
<html>
<body>
<?php
$a = 0;
$b = 0;
for( $i=0; $i<5; $i++ )
{
$a += 10;
$b += 5;
}
echo ("At the end of
the loop a=$a and b=$b" );
?>
</body>
</html>
This will produce following result:
At the end of the loop a=50 and b=25
The while statement
The while statement will execute a block of code if and as
long as a test expression is true.
This example decrements a variable value on each iteration
of the loop and the counter increments until it reaches 10 when the evaluation
is false and the loop ends.
<html>
<body>
<?php
$i = 0;
$num = 50;
while( $i < 10)
{
$num--;
$i++;
}
echo ("Loop stopped
at i = $i and num = $num" );
?>
</body>
</html>
This will produce following result:
Loop stopped at i = 10 and num = 40
The do...while loop
statement
The do...while statement will execute a block of code at
least once - it then will repeat the loop as long as a condition is true.
Example
The following example will increment the value of i at least
once, and it will continue incrementing the variable i as long as it has a
value of less than 10:
<html>
<body>
<?php
$i = 0;
$num = 0;
do
{
$i++;
}while( $i < 10 );
echo ("Loop stopped
at i = $i" );
?>
</body>
</html>
This will produce following result:
Loop stopped at i = 10
The foreach loop
statement
The foreach statement is used to loop through arrays. For
each pass the value of the current array element is assigned to $value and the
array pointer is moved by one and in the next pass next element will be
processed.
Syntax
foreach (array as value)
{
code to be
executed;
}
Example
Try out following example to list out the values of an
array.
<html>
<body>
<?php
$array = array( 1, 2, 3,
4, 5);
foreach( $array as $value
)
{
echo "Value is $value \n";
}
?>
</body>
</html>
This will produce following result:
Value is 1
Value is 2
Value is 3
Value is 4
Value is 5
The break statement
The PHP break keyword is used to terminate the execution of
a loop prematurely.
Example
In the following example condition test becomes true when
the counter value reaches 3 and loop terminates.
<html>
<body>
<?php
$i = 0;
while( $i < 10)
{
$i++;
if( $i == 3 )break;
}
echo ("Loop stopped
at i = $i" );
?>
</body>
</html>
This will produce following result:
Loop stopped at i = 3
The continue
statement
The PHP continue keyword is used to halt the current
iteration of a loop but it does not terminate the loop.
Example
In the following example loop prints the value of array but
for which condition becomes true it just skip the code and next value is
printed.
<html>
<body>
<?php
$array = array( 1, 2, 3,
4, 5);
foreach( $array as $value
)
{
if( $value == 3 )continue;
echo "Value is $value <br
/>";
}
?>
</body>
</html>
This will produce following result
Value is 1
Value is 2
Value is 4
Value is 5
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