How to correctly limit the content and strip HTML?

I have been using this code for a long time :

$temp_arr_content = explode(
    " ",
    substr(
        strip_tags(
            get_the_content()
        ),
        0,
        720
    )
);
$temp_arr_content[count( $temp_arr_content ) - 1] = "";
$display_arr_content = implode( " ", $temp_arr_content );
echo $display_arr_content;
if( strlen( strip_tags( get_the_content() ) ) > 0 )
    echo "...";

To limit my content to 720 characters and strip html from it
However, today I used it again in my new theme but I noticed that it also outputs the HTML codes (the HTML code is not working, but shows up in the content) .

I have also used this code in my theme :

$excerpt = get_the_excerpt();
echo string_limit_words( $excerpt, 55 );

and this code on my Function.php :

function string_limit_words( $string, $word_limit ) {
    $words = explode( ' ', $string, ( $word_limit + 1 ) );
    if( count( $words ) > $word_limit )
        array_pop( $words );
    return implode( ' ', $words );
}

to limit words and strip HTML , however, when I change 55 to 150 the code does not work and it still shows 55 words.
can someone please help me resolve this issue ?
thanks

First, I wouldn’t modify the string/word length of the content. Semantically, you’re dealing with an excerpt, so let’s focus on that.

Second, to limit the number of words returned for the excerpt, simply filter excerpt_length:

<?php
function wpse52673_filter_excerpt_length( $length ) {
    // Return (integer) value for
    // word-length of excerpt
    return 150;
}
add_filter( 'excerpt_length', 'wpse52673_filter_excerpt_length' );
?>

The added benefit of using the_excerpt() is that, for auto-generated excerpts, no HTML is parsed. So, if you don’t use user-defined excerpts, you’re done.

However, if you do use user-generated excerpts, but still want to strip HTML tags, simply remove any or all of the following filters that are applied to the_excerpt:

add_filter( 'the_excerpt',     'wptexturize'      );
add_filter( 'the_excerpt',     'convert_smilies'  );
add_filter( 'the_excerpt',     'convert_chars'    );
add_filter( 'the_excerpt',     'wpautop'          );
add_filter( 'the_excerpt',     'shortcode_unautop');

To remove one, simply call, e.g.:

remove_filter( 'the_excerpt', 'wptexturize' );