PHP eval()Functions

PHP Misc 参考手册PHP Misc Reference Manual

Examples

Evaluate a string as PHP code:

<?php $string = "beautiful"; $time = "winter"; $str = 'This is a $string $time morning!'; echo $str. PHP_EOL; eval("\$str = \"$str\";"); echo $str; ?>

The above code outputs:

This is a $string $time morning!
This is a beautiful winter morning!


Definition and Usage

The eval() function evaluates a string as PHP code.

The string must be valid PHP code and must end with a semicolon.

Note:The return statement will immediately terminate the evaluation of the string.

Tip:This function is useful for storing code in database text fields for later evaluation.


Syntax

eval(phpcode)

Parameter Description
phpcode Required. Specifies the PHP code to be evaluated.

Technical Details

Return value: Returns NULL unless a return statement is called in the code string, in which case the value passed to the return statement is returned. If there is a parse error in the code string, the eval() function returns FALSE.
PHP Version: 4+


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