将段落中的第一个句子大写

Question

I am using WordPress and WP-O-Matic to automatically pull contents from different feeds. The contents are in all caps making the posts in the WordPress blog looks crappy. I tried using different techniques, but none of them seem to work flawlessly.

Here are some examples I tried:
How to uppercase the first letter in a sentence in php
How to capitalize first letter of first word in a sentence?

I am currently using this piece of code, but its not working like it should:

function fwisc_content($content) {
if ( is_single() ) {
global $post;
$string = get_the_content($post->ID);
$sentences = preg_split('/([.?!]+)/', $string, -1, PREG_SPLIT_NO_EMPTY|PREG_SPLIT_DELIM_CAPTURE);
$new_string = '';
foreach ($sentences as $key => $sentence) {
    $new_string .= ($key & 1) == 0?
        ucfirst(strtolower(trim($sentence))) :
        $sentence.' ';
}
return trim($new_string); 

} else { 
    return $content;
}
}
add_action( 'the_content', 'fwisc_content' );

The problem is this code removes all the <p></p> tags making the whole post looks like a single paragraph.

Here is what I need to do:
Sample Input:

<p>THIS IS THE FIRST SENTENCE. THIS IS THE SECOND SENTENCE! THIS IS THE THIRD SENTENCE.. THIS IS THE FOURTH SENTENCE! IS THIS THE FIFTH SENTENCE?</p>
<p>THIS IS THE FIRST SENTENCE. THIS IS THE SECOND SENTENCE! THIS IS THE THIRD SENTENCE.. THIS IS THE FOURTH SENTENCE! IS THIS THE FIFTH SENTENCE?</p>

Expected Output:

<p>This is the first sentence. This is the second sentence! This is the third sentence.. This is the fourth sentence! Is this the fifth sentence?</p>
<p>This is the first sentence. This is the second sentence! This is the third sentence.. This is the fourth sentence! Is this the fifth sentence?</p>

Please help

Answer 1

Try out the following code:

<style>
    p:first-letter
    {
    text-transform: uppercase;
    }
</style>
<?php
function upperFirstWord($str) {
    return preg_replace('/([.!?])\s*(\w)/e', "strtoupper('\\1 \\2')", ucfirst(strtolower($str)));
}

echo upperFirstWord("<p>THIS IS THE FIRST SENTENCE. THIS IS THE SECOND SENTENCE! THIS IS THE THIRD SENTENCE.. THIS IS THE FOURTH SENTENCE! IS THIS THE FIFTH SENTENCE?</p><p>THIS IS THE FIRST SENTENCE. THIS IS THE SECOND SENTENCE! THIS IS THE THIRD SENTENCE.. THIS IS THE FOURTH SENTENCE! IS THIS THE FIFTH SENTENCE?</p>");
?>

Hope this will help. Thank you :-)