Regular expression matching everything except a given regular expression

Question

I am trying to figure out a regular expression which matches any string that doesn\'t start with mpeg. A generalization of this is matching any string which doesn\'t start w

Answer 1

don't lose your mind with regex.

if len(mystring) >=4 and mystring[:4]=="mpeg":
    print "do something"

or use startswith() with "not" keyword

if len(mystring)>=4 and not mystring.startswith("mpeg")