Echo a variable inside a variable - php

Question

I'm trying to figure out how to echo a variable inside a variable.
This code below doesn't obviously work because I'm not echoing the variable
$tweet = get_field('tweet_msg'); //this is getting the string inputted by user in the custom field
$tweet_intent = '<div>TEST </div>';
but when ever I do PHP throws an error saying unexpected echo:
$tweet_intent = '<div style="margin-bottom:15px;">TEST </div>';
Full code:
add_filter( 'the_content', 'prefix_insert_post_ads' );
function prefix_insert_post_ads( $content ) {
$tweet = get_field('tweet_msg');
$tweet_intent = '<div style="margin-bottom:15px;">TEST </div>';
if ( is_single() && ! is_admin() ) {
return prefix_insert_after_paragraph( $tweet_intent, 2, $content );
}
return $content;
}
// Parent Function that makes the magic happen
function prefix_insert_after_paragraph( $insertion, $paragraph_id, $content ) {
$closing_p = '</p>';
$paragraphs = explode( $closing_p, $content );
foreach ($paragraphs as $index => $paragraph) {
if ( trim( $paragraph ) ) { $paragraphs[$index] .= $closing_p;
}
if ( $paragraph_id == $index + 1 ) {
$paragraphs[$index] .= $insertion;
}
} return implode( '', $paragraphs );
}

Answer 1

The problem reside in your <a href> syntax.
Assuming that, after get_field(), the value of $tweet is 'Hello-World', your code:
$tweet_intent = '<div style="margin-bottom:15px;">TEST </div>';
put in $tweet_intent this string:
(...)TEST </div>
└──────────────────────────────────────┘
As you can see, the quotation marks of href are closed before $tweet output.
You have to change your code in this way:
$tweet = get_field( 'tweet_msg' );
$tweet = rawurlencode( $tweet ); // only if encoding is not performed by get_field
$tweet_intent = '
<div style="margin-bottom:15px;">
TEST
</div>';