When working in PHP there are times when I want to see what a string is in HEX – a lot of times there are invisible characters that or non-printing strings that can throw your program or script for a loop.
If you save the string to a text file, you can use a hex editor utility, like
hexdump to take a look at the hex codes of the ASCII characters:
$ echo abcd > test.txt $ hexdump test.txt 0000000 61 62 63 64 0a 0000005 $
Now for the PHP version:
header('Content-type: text/plain; charset=utf-8'); $ascii = 'abcd'; $hex = unpack('H*',$ascii); // you can print out the hex result of the ascii conversion: print_r($hex); # Array # ( #  => 61626364 # ) // or for a nicer display you can add spaces between every two characters // and wrap the column every 6 characters (change to fit your needs) echo wordwrap(implode(' ', str_split($hex, 2)), 6); # 61 62 # 63 64