Learn PHP if Statements

Conditional statements are used to perform different actions based on different conditions.

PHP Conditional Statements

Very often when you write code, you want to perform different actions for different conditions. You can use conditional statements in your code to do this.
In PHP we have the following conditional statements:

• if statement - executes some code if one condition is true
• if...else statement - executes some code if a condition is true and another code if that condition is false
• if...elseif...else statement - executes different codes for more than two conditions
• switch statement - selects one of many blocks of code to be executed

PHP - The if Statement

The if statement executes some code if one condition is true.

Syntax

             if (condition) {
                // code to be executed if condition is true;
              }

Example

Output "Have a good day!" if 5 is larger than 3:

             if (5 > 3) {
                echo "Have a good day!";
              }

We can also use variables in the if statement:

Example

Output "Have a good day!" if $t is less than 20:

               $t = 14;

                if ($t < 20) {
                  echo "Have a good day!";
                }

PHP - The if...else Statement

The if...else statement executes some code if a condition is true and another code if that condition is false.

Syntax

             if (condition) {
                // code to be executed if condition is true;
              } else {
                // code to be executed if condition is false;
              }

Example

Output "Have a good morning!" if the current time is less than 10, and "Have a good day!" if the current time is less than 20. Otherwise it will output "Have a good night!":

               $t = date("H");

                if ($t < "10") {
                  echo "Have a good morning!";
                } elseif ($t < "20") {
                  echo "Have a good day!";
                } else {
                  echo "Have a good night!";
                }

PHP Shorthand if Statements

Short Hand If

To write shorter code, you can write if statements on one line.

Example

One-line if statement:

               $a = 5;

                if ($a < 10) $b = "Hello";
                
                echo $b

Short Hand If...Else

if...else statements can also be written in one line, but the syntax is a bit different.

Example

One-line if...else statement:

               $a = 13;

                $b = $a < 10 ? "Hello" : "Good Bye";
                
                echo $b;

This technique is known as Ternary Operators, or Conditional Expressions.

PHP Nested if Statement

Nested If

You can use one if statement inside another if statement, this is called a nested if statements.

Example

An if inside an if:

              $a = 13;

                if ($a > 10) {
                  echo "Above 10";
                  if ($a > 20) {
                    echo " and also above 20";
                  } else {
                    echo " but not above 20";
                  }
                }