PHP STATEMENT (CONTROL STRUCTURE)-IF-ELSE-SWITCH
Concept:
The if statement specifies a block of code to be executed if a condition is true:
Syntax:
if (condition) { block of code to be executed if the condition is true
}
}
Example:
<?php
<?php
$color="red";
if($color=="red")
{
echo "color is red";
}
?>
output:
color is red
?>
output:
color is red
Concept:
The else statement specifies a block of code to be executed if the condition is false:
Syntax:
if (condition) { block of code to be executed if the condition is true
} else {
block of code to be executed if the condition is false
}
} else {
block of code to be executed if the condition is false
}
IF ELSE EXAMPLE :
<?php
$color="red";
if($color=="red")
{
echo "color is red";
}
else
{
echo "not red color";
}
?>
PHP - The if...else-if ....else Statement :
Use the if....elseif...else statement to specify a new condition to test, if the first condition is false.
Concept:
The else if statement specifies a new condition if the first condition is false:
Syntax:
if (condition1) { block of code to be executed if condition1 is true
} else if (condition2) { block of code to be executed if the condition1 is false and condition2 is true
} else { block of code to be executed if no condition matched means condtion1 is false and condition2 is false.
}
} else if (condition2) { block of code to be executed if the condition1 is false and condition2 is true
} else { block of code to be executed if no condition matched means condtion1 is false and condition2 is false.
}
Example :
<?php
$color="red";
if($color=="red")
{
echo "color is red";
}
else if($color=="orange")
{
echo "color is orange";
}
else
{
echo "No color:";
}
?>
output:
color is red
or we can do in this manner too:
<?php
$arr = array("Excellent"=>"Green","Good"=>"blue");
$grade ="Good";
if(array_key_exists($grade,$arr))
echo $arr[$grade];
?>
The PHP switch Statement:
Use the switch statement to select one of many blocks of code to be executed.
Concept:
This is how it works:
- The switch expression is evaluated once.
- The value of the expression is compared with the values of each case.
- If there is a match, the associated block of code is executed.
· Break keyword, it breaks out of the switch block.
· This will stop the execution of more code and case testing inside the block.
· When a match is found, and the job is done, it's time for a break. There is no need for more testing.
· The default keyword specifies the code to run if there is no case match
Syntax:
switch(expression)
{
case n1:
code block to be executed if case n1 is matched.
break;
case n2:
code block to be executed if case n2 is matched.
break;
default:
default code block to be execute if no case matched
case n1:
code block to be executed if case n1 is matched.
break;
case n2:
code block to be executed if case n2 is matched.
break;
default:
default code block to be execute if no case matched
break;
}
}
Example :
<?php
$color="white";
switch($color)
{
case "red":
echo "color is red";
break;
case "blue":
echo "color is blue";
break;
case "orange":
echo "color is orange";
break;
default:
echo "no color";
break;
}
?>
==============================================================================================================================================
some other practice on statement simple example on nested if :
<?php
$a=50;
$b=40;
$c=30;
if($a>$b)
{
if($a>$c)
{
echo "a is greater";
}
}
if($b>$a)
{
if($b>$c)
{
echo "b is greater";
}
}
if($c>$a)
{
if($c>$b)
{
echo "c is greater ";
}
}
?>
output:
a is greater
==============================================================================================================================================
some other practice on statement simple example on nested if :
<?php
$a=50;
$b=40;
$c=30;
if($a>$b)
{
if($a>$c)
{
echo "a is greater";
}
}
if($b>$a)
{
if($b>$c)
{
echo "b is greater";
}
}
if($c>$a)
{
if($c>$b)
{
echo "c is greater ";
}
}
?>
output:
a is greater
============================================================================================================================================== SIMPLE APPLICATION FOR PRACTICE USING SWITCH SIMPLE CALCULATOR :
(1)write code for form.html:
<html>
<head>
<title>simple calculator</title>
</head>
<body>
<form action="cal.php" method="post">
enter value of a<input type="text" name="a">
enter value of b<input type="text" name="b">
<select name="cal">
<option value="add">Addition</option>
<option value="sub">Subtraction</option>
<option value="mul">Multiplication</option>
</select>
<input type="submit" name="submit" value="cal">
</form>
</body>
</html>
(2)write code for "cal.php" :
<?php
$cal=$_POST["cal"];
$a=$_POST["a"];
$b=$_POST["b"];
if($cal=="add")
{
$c=$a+$b;
echo"it is addition".$c;
}
else if($cal=="sub")
{
$c=$a-$b;
echo"it is subtraction".$c;
}
else if($cal=="mul")
{
$c=$a*$b;
echo"it is multiplication".$c;
}
else
{
echo"no calculation";
}
?>
OUTPUT:
AFTER CLICK ON CAL BUTTON ..
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