The match, search, FindAll, finditer differences of the RE in Python

Original address: http://blog.csdn.net/djskl/article/details/44357389

These four methods are a common way to look for a particular substring from a string or to determine whether a string conforms to a pattern.

1, Match re.match (pattern, string[, flags]) starts with the first letter, and if string contains the pattern substring, the match succeeds, returns the Match object, fails returns none, and if the pattern is End With $.2, search re.search (pattern, string[, flags]) if the string contains the pattern substring, the match object is returned, otherwise none is returned, note that if there are multiple pattern substrings in the string, only the first One.3, FindAll Re.findall (pattern, string[, flags]) returns all strings in string that match the pattern, returned as an array.4, Finditer re.finditer (pattern, string[, flags]) returns all strings in string that match the pattern, returning as iterators. If the match succeeds, match ()/Search () returns the Match object, and Finditer () returns an iterator to the match object, which gets the group (), groups, or group (index) methods of the match object to be called. The difference between group (), groups () and group (index) is as follows:>>> ImportRe>>>S= ' 23432werwre2342werwrew '  >>>P= R ' (\d*) ([a-za-z]*) '  >>>M=Re.match (P,s)>>>M.group ()' 23432werwre '  >>>M.group (0)' 23432werwre '  >>>M.group (1)' 23432 '  >>>M.group (2)' Werwre '  >>>M.groups () (' 23432 ',' Werwre ')>>>M=Re.findall (P,s)>>>M [(' 23432 ',' Werwre '), (' 2342 ',' Werwrew '), ("',"')]>>>P=R ' (\d+) '  >>>M=Re.match (P,s)>>>M.group ()' 23432 '  >>>M.group (0)' 23432 '  >>>M.group (1)' 23432 '  >>>M.groups () (' 23432 ',)>>>M=Re.findall (P,s)>>>m [' 23432 ',' 2342 ': Group (): A substring in the string that matches the pattern patterns;0): The result is the same as group (); groups (): A tuple of all groups, group (1) is a successful substring that matches the first group in Patttern, group (2) is the second, and so on, if the index is over the boundary, throw Indexerror;findall (): Return is the array of all groups, that is, the group composed of tuples of the array, the cluster in the string to form a tuple, the measure to form a tuple, These tuples together form a list, which is the return result of FindAll (). Also, if groups is a tuple with only one element, the return result of FindAll is the list of substrings, not the tuple's list. Example S="1113446777"Use regular expressions to divide s into1111,3, -,6,777>>> ImportRe>>>S=' 1113446777 '  >>>M=Re.findall (R ' (\d) \1* ', s)>>> Printm [' 1 ',' 3 ',' 4 ',' 6 ',' 7 ']>>>M=Re.search (R ' (\d) \* ', s)>>>M.group ()>>>M=Re.search (R ' (\d) \1* ', s)>>>M.group ()' 111 '  >>>M.groups () (' 1 ',)>>>M.group (0)' 111 '  >>>M.group (1)' 1 '  >>>M.group (2) Traceback (most recent): File"<stdin>", line1,inch <Module>  Indexerror: No such group>>>M=Re.finditer (R ' (\d) \1* ', s)>>>M.Next(). Group ()' 111 '  >>>M.Next(). Group ()' 3 '  >>>M.Next(). Group ()' a '  >>>M.Next(). Group ()' 6 '  >>>M.Next(). Group ()' 777 '  >>>M.Next(). Group () Traceback (most recent call last): File"<stdin>", line1,inch <Module>  stopiterationAnother example:>>>P= R ' (\d) \1+ ([a-za-z]+) '  >>>S= ' 1111werwrw3333rertert4444 '  >>>P= R ' (\d) \1+ ([a-za-z]*) '  >>> ImportRe>>>Re.findall (P,s) [(' 1 ',' WERWRW '), (' 3 ',' Rertert '), (' 4 ',"')]>>>M=Re.search (P,s)>>>M.group ()' 1111WERWRW '  >>>M.group (1)' 1 '  >>>M.group (2)' WERWRW '  >>>M.groups () (' 1 ',' WERWRW ')>>>M=Re.finditer (P,s)>>>M.Next(). Group ()' 1111WERWRW '  >>>M.Next(). Group ()' 3333rertert '  >>>M.Next(). Group ()' 4444 '  >>>M.Next(). Group () Traceback (most recent call last): File"<stdin>", line1,inch <Module>  stopiteration  

The match, search, FindAll, finditer differences of the RE in Python