shortcodes output before content [duplicate]

Possible Duplicate:
problem with short code

Shortcodes are broken.

For those of you playing at home, heres an easy step by step to replicate my problem.

1) Open a fresh WordPress install (3.4.2).

2) Go into twentyeleven/functions.php and add the following:

function test() {
echo '-TEST-';
}
add_shortcode('testshortcode', 'test');

3) Edit the ‘hello world’ post to say:

Welcome to WordPress. This is your first post. Edit or delete it, then start blogging! 
[testshortcode] 
foobar

4) Save and view, my results look like the following:

-TEST-
Welcome to WordPress. This is your first post. Edit or delete it, then start blogging!
foobar

when it should look like this:

Welcome to WordPress. This is your first post. Edit or delete it, then start blogging!
-TEST-
foobar

What on earth is going on here?

Shortcode callbacks have to return, not output. So use the following:

function test() {
    return '-TEST-';
}
add_shortcode( 'testshortcode', 'test' );

More info: http://codex.wordpress.org/Shortcode_API

If you have to use echo you can also do it this way(useful if there’s a lot of markup & it’s difficult working with strings)-

function test() {
    ob_start();
    echo '-TEST-';
    return ob_get_contents();
}
add_shortcode( 'testshortcode', 'test' );