Why does `(c*)|(cccd)` match `ccc`, not `cccd`?

Your regex ((c*)|(cccd)) is saying match either one of two things:\n\n\n0 or unlimited c's\nThe literal sequence cccd\n\n\nBecause regular expressions are greedy, it consumes the ccc string as the match, so that is what you're returning. It will first try what ever comes first (in this case c*, and if it is able to make a match, then it will.\n\nTo correct to what you want, try the regex: (cccd)|(c*). With this:\n\n>>> mo = re.match('(cccd)|(c*)', 'cccd')\n>>> mo.group(0)\n'cccd'\n\n\nExample is here: https://regex101.com/r/aU8pE7/1",

Regex patterns are evaluated from left to right. Put the pattern which has higher precedence as first (to the left of |) and the lower precedence as second (to the right of |). Note that the second pattern was not allowed to match the text which was already matched by the first pattern. That is, regex engine by default won't do overlapping matches. To make the regex engine to do overlapping match then you need to put your pattern inside a capturing group and again put the capturing group inside a positive lookaround assertion (positive lookahead and positive lookbehind).\n\nmo = re.match('(cccd)|(c*)', 'cccd')\n",