how to trim last character in php code example

Example 1: php remove last character from string if comma

$string = rtrim($string, ',');

Example 2: remove last character from string in php

$arrStr = 'Str1, Str2, str3, ';
echo rtrim($arrStr, ", "); //Str1, Str2, str3
echo substr_replace($arrStr, "", -2); //Str1, Str2, str3
echo substr($arrStr, 0, -2); // Str1, Str2, str3