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Python Library Reference |  |
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Python Library Reference | |
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String objects have one unique built-in operation: the %
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.
The right argument should be a tuple with one item for each argument
required by the format string; if the string requires a single
argument, the right argument may also be a single non-tuple
object.2.5 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.2.6 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. For example:
>>> count = 2 >>> language = 'Python' >>> print '%(language)s has %(count)03d quote types.' % vars() Python has 002 quote types.
In this case no * specifiers may occur in a format (since they
require a sequential parameter list).
Additional string operations are defined in standard module string and in built-in module re.
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Python Library Reference | |
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