Left padding a string with blanks (no truncation:
$padded = sprintf("%${pad_len}s", $text);
# Right padding a string with blanks (no truncation):
$padded = sprintf("%-${pad_len}s", $text);
# Left padding a number with 0 (no truncation): 
$padded = sprintf("%0${pad_len}d", $num);
# Right padding a string with blanks using pack (will truncate):
$padded = pack("A$pad_len",$text);

##</code><code>##

$padded = $pad_char x ( $pad_len - length( $text ) ).$text;
$padded = $text . $pad_char x ($pad_len - length($text));

##</code><code>##

substr($text, 0, 0)=$pad_charx($pad_len-length($text));
$text .= $pad_char x ($pad_len - length($text));