PHP conditional statements explanation and programs
PHP Conditional Statements
While coding, you may get to a point where your results can
only be gotten when a condition is valid. We make use of conditional statements. Conditional statements are statements
that can only be executed based on the fulfillment of a particular
condition(s).
There are basically 4 different types of conditional statements in PHP,
1) The if
statement
With the if statement your
code only executes only when the condition is true.
Syntax:
if(condition){ //code to be executed when condition is true }
Example:
Let's check if a mark entered is greater than or equal to 80.
If true an
A grade is given.
PHP Code:
<?php
//defining a variable
$mark = 120;
if($mark >= 80){
echo "you have an A";
}
?>
Output
you have an A
2) The
if...else statements
The if...else
statement is used when a condition is satisfied and when it is not
satisfied. So it's used when the condition is either true or false.
Syntax:
if (condition){ //code to be executed when true } else { //code to be executed when false }
Example:
Here, we are going to check if the letter entered is an F
which will display female else we display male.
PHP Code:
<?php
//defining a variable
$gender = 'F';
if ($gender == 'F'){
echo "FEMALE";
}
else { echo "MALE";
}
?>
Output
FEMALE
3) The
if...elseif...else statements
In a situation where you have several conditions, for example
a program to grade students based on their marks with the letters A, B, C, D,
F. the if...elseif...else is
used for this.
Syntax:
if (condition1){ //code 1 to be executed } elseif(condition2) { //code 2 to be executed } else{ //code to be executed if code 1 and code 2 are not true }
Example:
We are going to grade students with the letters A, B, C, D, F
based on their marks on 100.
PHP Code:
<?php
//defining a variable
$marks = 75;
if ($marks>79){
echo "A";
}
elseif($marks<=79&& $marks>60) { echo "B";
}
elseif($marks<=60&& $marks>50) { echo "C";
}
elseif($marks=50) { echo "D";
}
else{
echo "F";
}
?>
Output
B
4) The
nested if...else statements
When you find if...else
statements inside an if...else
statement the statements are nested.
With this statement, you can get alternatives results when a condition is true or false.
Syntax:
if (condition 1 ) { if (condition 2 ) { // code1 to be executed } else { // code 2 to be executed } } else { // code 4 to be executed }
Example:
Let's compare tow numbers using
the nested if statement.
PHP code:
<?php
// defining variables
$number1 = 40;
$number2 = 12;
if ($number1 != $number2) {
echo 'number1 is different
from number2';
echo '<br>';
if ($number1 > $number2) {
echo
'number1 is greater than number2';
} else {
echo
'number2 is greater than number1';
}
} else {
echo 'number1 is equal to
number2';
}
?>
Output
number1
is different from number2
number2
is greater than number1
5) The switch statement
The switch statement is
very similar to the if...else statement. But in the cases where
your conditions are complicated like you need to check a condition with
multiple constant values, a switch statement is preferred to
an if...else. The examples below will help us better understand
the switch statements.
Syntax:
switch (n)
{
case constant1:
// code to be executed if n is equal to
constant1;
break;
case constant2:
// code to be executed if n is equal to
constant2;
break;
.
.
.
default:
// code to be executed if n doesn't match
any constant
}
Example:
Let's rewrite the example of
if…..else statements using switch statements,
<?php
//variable definition
$gender = 'M';
switch ($gender) {
case 'F':
echo
'F is FEMALE';
break;
case 'M':
echo
'M is MALE';
break;
default:
echo
'Invalid choice';
}
?>
Output
M
is MALE
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