What is the meaning of \x00 , \x04 in PHP

Question

i have some codes having the \\x00 and \\x04 hex codes, what does it means?

$str= implode(\"\\x00\",          


        

Answer 1

\xHH is an escape sequence that describes the byte with that hexadecimal value.

So \x00 describes the byte with the value 0, \x04 the byte with the value 4. Note that this escape sequence is only interpolated in double quoted strings.