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PHP conditional statements: In this article, we are going to learn about the various conditional statements in PHP programming language with examples.
Submitted by Kongnyu Carine, on May 20, 2019

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:

	//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:

    //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:

    //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:

// defining variables
$number1 = 40;
$number2 = 12;

if ($number1 != $number2) {
    echo 'number1 is different from number2';
    echo '
';
    if ($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,

//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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