4.2.6 Examples

Simulating scanf()

Python does not currently have an equivalent to scanf().  Regular expressions are generally more powerful, though also more verbose, than scanf() format strings. The table below offers some more-or-less equivalent mappings between scanf() format tokens and regular expressions.

scanf() Token  Regular Expression 
%c .
%5c .{5}
%d [-+]\d+
%e, %E, %f, %g [-+](\d+(\.\d*)?|\d*\.\d+)([eE]\d+)?
%i [-+](0[xX][\dA-Fa-f]+|0[0-7]*|\d+)
%o 0[0-7]*
%s \S+
%u \d+
%x, %X 0[xX][\dA-Fa-f]

To extract the filename and numbers from a string like

    /usr/sbin/sendmail - 0 errors, 4 warnings

you would use a scanf() format like

    %s - %d errors, %d warnings

The equivalent regular expression would be

    ([^\s]+) - (\d+) errors, (\d+) warnings

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