What argument to use in query_posts to get posts with given letter?

Put this in your functions.php:

add_filter('query_vars', 'letter_queryvar' );
function letter_queryvar( $qvars )
{
  $qvars[] = 'letter';
  return $qvars;
}

add_filter('posts_where', 'letter_where' );
function letter_where( $where )
{
    global $wp_query;
    global $wpdb;

    if( isset( $wp_query->query_vars['letter'] )) {

       $where .= " AND $wpdb->posts.post_title LIKE '".$wp_query->query_vars['letter']."%'";
    }
    return $where;
}

Now You can query posts like this:

query_posts('letter=A');

The code returns Posts with titles that begins with the letter A.
If you want Posts where the post content begins with the letter A change this:

$where .= " AND $wpdb->posts.post_title LIKE '".$wp_query->query_vars['letter']."%' ";

to this:

$where .= " AND $wpdb->posts.post_content LIKE '".$wp_query->query_vars['letter']."%' ";

Thank you, thank you, but It doesn’t work.

Try it with the code from my last post (just above yours).

Sorry, my question was not right. I want to get all posts whose titles begin with a specific letter, so basically the code that you gave me first.
But doesn’t work.

Does it return any posts or none when you query the loop?

For testing try putting this after query_posts.

query_posts('letter=A');
global $wp_query;
echo '<pre>';
print_r($wp_query);
echo '</pre>';

Can you see if “letter” is in the “query_vars” Array.

Can you paste and submit the full code of the template file where you query the loop into a pastebin.com and post the link to it here? see the Forum Rules for posting code and using the pastebin.

Here’s what the output of print_r is:

WP_Query Object
(
[query_vars] => Array
(
[letter] => A
…..

The code in my template is:

<?php
query_posts('letter=A');
while (have_posts()) : the_post();
 echo 'test';
endwhile;
?>

try that with:

<?php
query_posts('letter=A');
while (have_posts()) : the_post();
 the_title();
endwhile;
?>

No, nothing ??

So it returns nothing?
You do have post titles that start with an A?

Very strange because this works on my site.

Yeah nothing. I have only 2 posts that start with an A (Atmosphere, Amber).
If I put query_posts(‘category_name=test’), it gets the posts from test category.

I have wordpress 3.2.1 by the way.

Maybe you have a older version.

No, I have the same WordPress version.

Are there multiple loops in your template file? Can you put the full template file in a pastebin.