How to use switch statement in PHP (example analysis)

In the previous article, I brought you "5 minutes to master PHP's if else syntax and NULL data type". This article introduces the basic statement of PHP's if-else in detail. , today we continue to look at a statement that is more efficient than if-else, which is PHP's switch statement. I hope to be helpful!

PHP switch statement

The switch statement is similar to the if-else statement. They both perform different actions based on different conditions, but if-else The efficiency of statement judgment is low. We have a better way, which is the switch statement. If we want to be able to use the switch statement, we must first know its basic syntax format.

The switch statement consists of an expression and multiple case tags. The example is as follows:

switch (表达式) {
     case 条件1:
        动作1;
         break;
     case 条件2:
         动作2;
         break;
     default://未满足条件1、条件2而剩余的条件
         动作3;
}

When the switch statement is executed, the expression will be calculated once , and then compare the value in the expression with the value in the case in sequence. If they are equal, the corresponding action or statement will be executed. If they are not equal, the comparison will continue to the next case, and so on until the switch statement. End or encounter break.

Generally speaking, there will be a default value at the end of the switch statement, which is default in the above formula. If no matching conditions are found in the previous case, it will be executed. The default statement is default. This is somewhat similar to the else statement.

At the same time, we should also pay attention to some things when using switch statements:

• The number of case statements can continue to increase. However, there must be a space between the case label and the value after the case label. Do not write a semicolon (;) after the case, followed by a colon (:).

• Do not write the judgment interval after the case, such as ($a > 2 or $a == 3)

• Switch in the variable It is best to be an integer or a string, not a Boolean type, because Boolean judgment is more suitable for if...else..

• If the break in each case is removed, then each The code blocks in each case will be executed in sequence.

• The switch statement does not need to be written as default, but in order to develop good habits, it is recommended to retain the default statement.

• The difference from the if statement is that curly braces must be added after the switch statement.

<?php
$a ="好好学习";
switch ($a)
{
case "福如东海":
    echo "福如东海，寿比南山";
    break;
case "好好学习":
    echo "好好学习，天天向上";
    break;
case "一夫当关":
    echo "一夫当关，万夫莫开";
    break;
default:
    echo "nothing";
}
?>

Output result:

#Output: Study hard and make progress every day; use the switch statement to match the expression with the conditions case action output.

Another example:

<?php
 $dir=&#39;nothing&#39;;
 switch ($dir) {
     case &#39;west&#39;:
         echo &#39;西&#39;;
         break;
     case &#39;east&#39;:
         echo &#39;东&#39;;
         break;
     case &#39;north&#39;:
         echo &#39;北&#39;;
         break;
     case &#39;sourth&#39;:
         echo &#39;南&#39;;
         break;
     default:
         echo &#39;未知&#39;;
         break;
 }
 ?>

Output result:

Since no matching conditions were found in the previous case, then The default statement, which is default, will be executed. Therefore, the output result is default: unknown.

Recommended learning: "PHP Video Tutorial"

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