Question

I am tring this method to find the common characters in two strings namely, $a and $r, but the first character isn’t getting printed . Moreover the $already collects the common characters and prevents them from being printed for multiple times( I need each character to be printed once only) but it isn’t doing so. Please tell me what errors I am making.

<?php
$a="BNJUBCI CBDIDIBO";
$r="SBKJOJLBOU";
$already="";
for($i=0;$i<strlen($r);$i++)
{
   if (stripos($a,$r[$i])!=FALSE)
   {
        if (stripos($already,$r[$i])==FALSE)
        {
            $already=$already.$r[$i];
            echo "already=".$already."<br>";
            echo $r[$i]."<br>";
        }
   }
}
?>

Answer 1

Use !==FALSE instead of !=FALSE. The problem is that stripos returns 0 if the needle is at the start of the haystack, and 0 is falsy. By using !== you are forcing it to ensure the result is actually false, and not just 0.

This is actually listed in the docs. An “RTM” might be appropriate here.

Warning
This function may return Boolean FALSE, but may also return a non-Boolean value which evaluates to FALSE. Please read the section on Booleans for more information. Use the === operator for testing the return value of this function.