Is it possible to define variables in a wordpress shortcode, and then call the shortcode using a specific variable?

Question

This is my first go at making my own shortcode.

What I am trying to do

I have 11 different outputs for star ratings I want to be able to use in posts. I want to wrap it all into one shortcode, and be able to call the specific rating I want. I imagine something like this:

[star_rating grade="3"]

That would produce 3 out of five stars.

What I know

I have figured out how to accomplish this using a separate function and shortcode for each grade, but it seems very redundant.

What I have

This is what I have managed to get so far:

function star_rating_5_func( $atts ) {
    $a = shortcode_atts( array(
        '5' => '<i class="fa fa-star"></i><i class="fa fa-star"></i><i class="fa fa-star"></i><i class="fa fa-star"></i><i class="fa fa-star"></i>'

    ), $atts );

    return "{$a['5']}";

}
add_shortcode( 'star_rating_5', 'star_rating_5_func' );

function star_rating_4_5_func( $atts ) {
    $a = shortcode_atts( array(
        '4_5' => '<i class="fa fa-star"></i><i class="fa fa-star"></i><i class="fa fa-star"></i><i class="fa fa-star"></i><i class="fa fa-star-half-o"></i>'

    ), $atts );

    return "{$a['4_5']}";

}
add_shortcode( 'star_rating_4_5', 'star_rating_4_5_func' );

This produces a five star rating for [star_rating_5] and a 4.5 star rating for [star_rating_4_5].

I'm not very fluent in php, so its a lot of copy and paste at this point. I know you can define variables, and it seems I should be able to simply call a specific one to get the output I want.

Is this possible?

[star_rating grade="3"] -EXAMPLE

Answer 1

I think you are looking for this-

function star_rating( $atts ) {
$max = 5;
$atts = shortcode_atts(
    array(
        'grade' => $max, // default
    ), $atts );

$star_icons = '';

$full_star = floor( $atts['grade'] );
for( $i=1; $i<=$full_star; $i++ ) {
    $star_icons .= '<i class="fa fa-star"></i>';
}

$half_star = 0;
if( (int) $atts['grade'] != $atts['grade'] ){
    $half_star = 1;
    $star_icons .= '<i class="fa fa-star-half-o"></i>';
}

//considering you want to show empty stars as well
$empty_star = $max - $half_star - $full_star;
for( $i=1; $i<=$empty_star; $i++ ) {
    $star_icons .= '<i class="fa fa-star-o"></i>';
}

return $star_icons;

}
add_shortcode( 'star_rating', 'star_rating' );

Note:

1. all fraction numbers are considered as 1 half-star. I mean, 2.5 and 2.6 will produce same output.
2. these type of stuffs should be handled with CSS.
3. Tested and working.

Answer 2

Your shortcode should look something like that

function se224467_shotcode_star_rating( $atts ) {

    $a = shortcode_atts( array(
        'grade' => 5,
    ), $atts );

    $full_stars = floor( $a['grade'] );

    // full stars
    $output = str_repeat( '<i class="fa fa-star"></i>', $full_stars );

    // if not a whole number append a halt
    if ( floatval($full_stars) !== floatval( $a['grade'] ) ) {
        $output .= '<i class="fa fa-star-half-o"></i>';
    }

    return $output;
}

add_shortcod( 'star_rating', 'se224467_shotcode_star_rating' );

I haven't tested it. You should be able to pass floats like [star_rating grade=3.5]. In fact anything but a whole number will get you a half star. This won't account for empty stars. See mukto90 answer for those.

Hope you get the idea.

Also consult the Codex about Shortcode API - Handling Attributes