regex - Regular expression that doesn't accept single 0 but does accept 10 -

i have regular expression:

^[ 0-9a-z] [ 0-9]{4}[0-9][/ ][ 0-9a-z]$

and works fine, have exclude 0 in construct [ 0-9]{4}[0-9] in way.

the string a 0/a should not match

the string a 10/a should match

so have check if first occurrence of number in second group 0 or not.

how can that? if or not clear, so.

so have check if first occurrence of number in second group 0 or not.

i think need negative lookahead:

^[ 0-9a-z] (?! *0)[ 0-9]{4}[0-9][/ ][ 0-9a-za-z]$            ^^^^^^^ 

see regex demo.

since [ 0-9]{4}[0-9] matches 4 digits or spaces (there may 4 spaces) , [0-9] matches digit obligatorily, (?! *0) make sure pattern above not match spaces followed 0.