Question

What I have and want to do

• I have an input area.

• I have a JS script what reads the input area‘s innerHTML and encodes it using encodeURICompontent then sends the value to evaluate.php?code=+value;

• I have an evaluate.php what GET‘s the code‘s value from the URL and returns an evaluated value using eval($code) to the javascript.

• And at the end it puts the xmlHttp.responseText to a div.

But I get this error when the eval is executed:

Parse error: syntax error, unexpected ‘”‘, expecting T_STRING in /Applications/MAMP/htdocs/Apps/editor/includes/exe.php(5) : eval()’d code on line 1

Evaluate.php

if(isset($_GET["code"])){
    $e = $_GET["code"];
    echo eval($e);
}

The value what I try to evaluate is just:

echo "Hello World!";

Then this is looks like in $_GET["code"] as:

echo \"Hello World!\";

Answer 1

According to PHP’s documentation:

eval() returns NULL unless return is
called in the evaluated code, in which
case the value passed to return is
returned. If there is a parse error in
the evaluated code, eval() returns
FALSE and execution of the following
code continues normally. It is not
possible to catch a parse error in
eval() using set_error_handler().

So I think there may be a problem when you run echo eval($e).

P.S. It’s best practice not to use double quotes in PHP unless a variable is contained within those quotes. For example, use "Hello, $name" and use 'Hello, Bob'.