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eval

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eval -- Evaluate a string as PHP code

Description

mixed eval (string code_str)

eval() evaluates the string given in code_str as PHP code. Among other things, this can be useful for storing code in a database text field for later execution.

There are some factors to keep in mind when using eval(). Remember that the string passed must be valid PHP code, including things like terminating statements with a semicolon so the parser doesn't die on the line after the eval(), and properly escaping things in code_str.

Also remember that variables given values under eval() will retain these values in the main script afterwards.

A return statement will terminate the evaluation of the string immediatley. In PHP 4 you may use return to return a value that will become the result of the eval() function while in PHP 3 eval() was of type void and did never return anything.

Example 1. Eval() example - simple text merge 


<?php
$string = 'cup';
$name = 'coffee';
$str = 'This is a $string with my $name in it.<br>';
echo $str;
eval ("\$str = \"$str\";");
echo $str;
?>

The above example will show: 

This is a $string with my $name in it.
This is a cup with my coffee in it.

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