What does else mean in php

PHP is a server scripting language commonly used to generate dynamic content in web development. In PHP, if/else conditional statements are widely used to determine the flow of the program.

else is a keyword in if/else conditional statements, used to perform alternative operations when the conditions are not met. When the expression of the if conditional statement is false, the program will continue to execute the code in the next else statement block.

For example, the following is sample code for using if/else statements in PHP:

$score = 85;

if ($score >= 90) {
  echo "优秀";
} else {
  echo "良好";
}

In this example, the value of the $score variable is 85. If the value of $score is greater than or equal to 90, the program will output "excellent"; otherwise, the program will output "good". Because the value of $score is 85, the program will execute the else statement block.

In addition to the else keyword, if/else conditional statements have other keywords. The elseif keyword is used to add multiple conditional branches after the original if statement block. The switch statement is used to select one of the branches for execution based on the value of the variable.

In PHP, the else statement block usually performs an alternative action, such as outputting an error message, or taking other actions. Developers can use conditional statements in if/else statements according to specific needs. For example, here is another example of using if/else statements in PHP, where the program outputs a welcome message when the username and password entered are correct, otherwise it outputs an error message:

$username = $_POST['username'];
$password = $_POST['password'];

if ($username == 'admin' && $password == '123456') {
  echo "欢迎登录！";
} else {
  echo "用户名或密码错误，请重试。";
}

In this example, the program will Different operations are performed based on whether the username and password entered by the user match the preset values. If the user name and password are correct, the program will output "Welcome to log in!"; otherwise, the program will output "The user name or password is incorrect, please try again.".

In short, else is the keyword of if/else conditional statement in PHP, which is used to perform alternative operations when the if condition is not met. Developers can use conditional statements in if/else statements to handle different situations according to specific needs.

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