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The GNU Awk User's Guide

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5.4 Controlling Numeric Output with print

When the print statement is used to print numeric values, awk internally converts the number to a string of characters and prints that string. awk uses the sprintf function to do this conversion (see section String Manipulation Functions). For now, it suffices to say that the sprintf function accepts a format specification that tells it how to format numbers (or strings), and that there are a number of different ways in which numbers can be formatted. The different format specifications are discussed more fully in Format-Control Letters.

The built-in variable OFMT contains the default format specification that print uses with sprintf when it wants to convert a number to a string for printing. The default value of OFMT is "%.6g". The way print prints numbers can be changed by supplying different format specifications as the value of OFMT, as shown in the following example:

$ awk 'BEGIN {
>   OFMT = "%.0f"  # print numbers as integers (rounds)
>   print 17.23, 17.54 }'
-| 17 18

According to the POSIX standard, awk's behavior is undefined if OFMT contains anything but a floating-point conversion specification. (d.c.)

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  Copyright 2003   by The Free Software Foundation     Updated Jun 2003