hide certain category from single post - php

Question

I need to limit number of categories display in a single post on wordpress using this script
function swift_list_cats($num){
$temp=get_the_category();
$count=count($temp);// Getting the total number of categories the post is filed in.
for($i=0;$i<$num&&$i<$count;$i++){
//Formatting our output.
$cat_string.=''.$temp[$i]->cat_name.'';
if($i!=$num-1&&$i+1<$count)
//Adding a ',' if it’s not the last category.
//You can add your own separator here.
$cat_string.=' | ';
}
echo $cat_string;
}
But I also need to hide some categories. How would I do that?

Answer 1

Simple answer is to return a new count not based on the length of your array so
for($i=0;$i<$num&&$i<$count;$i++){
becomes:
for($i=0;$i<10;$i++){
or use $temp = array_slice(get_the_category(), //ofset 0, //length 10);
Array slice info can be seen here.
If you need to hide some values, this would be far easier to do by adding a hidden column to your database and select values WHERE hidden = 0. However to address your question.You need to know which values you want to hide. Store these in an array and do the following.
function swift_list_cats($num){
$hiddenArray = [12, 105];
//change offset and limit to what you desire removing the slashes and labels
$temp = array_slice(get_the_category(), 0, 10);
$count=count($temp);
$cat_string = '';
for($i=0;$i<$num&&$i<$count;$i++){
if(in_array($temp[i]->cat_ID, $hiddenArray)){
continue;
}
$cat_string.=''.$temp[$i]->cat_name.'';
if($i!=$num-1&&$i+1<$count)
$cat_string.=' | ';
}
echo $cat_string;
}
$hiddenArray is the array you populate with your category IDs that you want hidden