PHP If...ElseStatements

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

PHP Conditional Statements

When you are writing code, you often need to perform different actions for different decisions. You can use conditional statements in your code to accomplish this task.

In PHP, the following conditional statements are provided:

• if statement- Executes code when the condition is true
• if...else statement- Executes a block of code when the condition is true, and another block of code when the condition is not true
• if...elseif....else statement- Executes a block of code when one of several conditions is true
• switch statement- Executes a block of code when one of several conditions is true

PHP - if Statement

The if statement is used toexecute code only when the specified condition is true.。

Syntax

if (条件) {
    条件成立时要执行的代码;
}

If the current time is less than 20, the following example will output "Have a good day!":

PHP - if...else Statement

Execute a block of code when the condition is true, and another block of code when the condition is not true, use the if....else statement.

Syntax

if (条件) {
    条件成立时执行的代码;
} else {
    条件不成立时执行的代码;
}

If the current time is less than 20, the following example will output "Have a good day!", otherwise it will output "Have a good night!":

PHP - if...elseif....else Statement

To execute a block of code when one of several conditions is true, use the if....elseif...else statement.

Syntax

if (条件) {
    if 条件成立时执行的代码;
} elseif (条件) {
    elseif 条件成立时执行的代码;
} else {
    条件不成立时执行的代码;
}

If the current time is less than 10, the following example will output "Have a good morning!"; if the current time is not less than 10 and is less than 20, it will output "Have a good day!"; otherwise it will output "Have a good night!":

PHP - switch Statement

The switch statement will be explained in the next chapter.