%
operator (modulo) with a string left argument interprets this string
as a C sprintf format string to be applied to the right argument, and
returns the string resulting from this formatting operation.
Unless the format string requires exactly one argument, the right
argument should be a tuple of the correct size. The following format
characters are understood: %, c, s, i, d, u, o, x, X, e, E, f, g, G.
Width and precision may be a * to specify that an integer argument
specifies the actual width or precision. The flag characters -, +,
blank, # and 0 are understood. The size specifiers h, l or L may be
present but are ignored. The %s conversion takes any Python
object and converts it to a string using str() before
formatting it. The ANSI features %p and %n
are not supported. Since Python strings have an explicit length,
%s conversions don't assume that '*0' is the end of
the string.
For safety reasons, floating point precisions are clipped to 50;
%f conversions for numbers whose absolute value is over 1e25
are replaced by %g conversions.(1)
All other errors raise exceptions.
If the right argument is a dictionary (or any kind of mapping), then
the formats in the string must have a parenthesized key into that
dictionary inserted immediately after the % character, and
each format formats the corresponding entry from the mapping. E.g.
>>> count = 2
>>> language = 'Python'
>>> print '%(language)s has %(count)03d quote types.' % vars()
Python has 002 quote types.
>>>
Additional string operations are defined in standard module
string and in built-in module regex.