On Fri, 2009-03-13 at 21:01 +0000, tinn...@isbd.co.uk wrote: > I've had this trouble before, how do I find the details of how "in" > works in the documentation. E.g. the details of:- > > if string in bigstring: > > It gets a mention in the "if" section but not a lot. >
>From http://docs.python.org/reference/expressions.html#in The operators in and not in test for collection membership. x in s evaluates to true if x is a member of the collection s, and false otherwise. x not in s returns the negation of x in s. The collection membership test has traditionally been bound to sequences; an object is a member of a collection if the collection is a sequence and contains an element equal to that object. However, it make sense for many other object types to support membership tests without being a sequence. In particular, dictionaries (for keys) and sets support membership testing. For the list and tuple types, x in y is true if and only if there exists an index i such that x == y[i] is true. For the Unicode and string types, x in y is true if and only if x is a substring of y. An equivalent test is y.find(x) != -1. Note, x and y need not be the same type; consequently, u'ab' in 'abc' will return True. Empty strings are always considered to be a substring of any other string, so "" in "abc" will return True. Changed in version 2.3: Previously, x was required to be a string of length 1. For user-defined classes which define the __contains__() method, x in y is true if and only if y.__contains__(x) is true. For user-defined classes which do not define __contains__() and do define __getitem__(), x in y is true if and only if there is a non-negative integer index i such that x == y[i], and all lower integer indices do not raise IndexError exception. (If any other exception is raised, it is as if in raised that exception). -- http://mail.python.org/mailman/listinfo/python-list
