The difference between the short tag and the long tag in PHP

The so-called identifier refers to the name of the variable.

The names of functions and classes are also identifiers.

PHP rules about identifiers:

• Identifiers can be letters, numbers, underscores of any length, and must not start with a number.

• Identifiers in PHP are case-sensitive, but function names are an exception.

• The variable name can be the same as the function name. But it should be avoided as much as possible.

• You cannot create a function with the same name as an existing function.

short tags are only used to output variables or expressions. The general usage is

<?=$a?>
<?=(表达式)?>

which is equivalent to

<?php echo $a?>
<?php echo (表达式)?>

does not support Such as if, for and other structures.
If you write

<?if(...?>

, it will become

<!--if(...-->

, so when writing a program, you must use long tags and insert the output into the html Short markers are sometimes used.

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