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(gawk.info)Control Letters

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Format-Control Letters
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   A format specifier starts with the character `%' and ends with a
"format-control letter"--it tells the `printf' statement how to output
one item.  The format-control letter specifies what _kind_ of value to
print.  The rest of the format specifier is made up of optional
"modifiers" that control _how_ to print the value, such as the field
width.  Here is a list of the format-control letters:

`%c'
     This prints a number as an ASCII character; thus, `printf "%c",
     65' outputs the letter `A'. (The output for a string value is the
     first character of the string.)

`%d, %i'
     These are equivalent; they both print a decimal integer.  (The
     `%i' specification is for compatibility with ISO C.)

`%e, %E'
     These print a number in scientific (exponential) notation; for
     example:

          printf "%4.3e\n", 1950

     prints `1.950e+03', with a total of four significant figures,
     three of which follow the decimal point.  (The `4.3' represents
     two modifiers, discussed in the next node.)  `%E' uses `E' instead
     of `e' in the output.

`%f'
     This prints a number in floating-point notation.  For example:

          printf "%4.3f", 1950

     prints `1950.000', with a total of four significant figures, three
     of which follow the decimal point.  (The `4.3' represents two
     modifiers, discussed in the next node.)

`%g, %G'
     These print a number in either scientific notation or in
     floating-point notation, whichever uses fewer characters; if the
     result is printed in scientific notation, `%G' uses `E' instead of
     `e'.

`%o'
     This prints an unsigned octal integer.

`%s'
     This prints a string.

`%u'
     This prints an unsigned decimal integer.  (This format is of
     marginal use, because all numbers in `awk' are floating-point; it
     is provided primarily for compatibility with C.)

`%x, %X'
     These print an unsigned hexadecimal integer; `%X' uses the letters
     `A' through `F' instead of `a' through `f'.

`%%'
     This isn't a format-control letter but it does have meaning--the
     sequence `%%' outputs one `%'; it does not consume an argument and
     it ignores any modifiers.

   *Note:* When using the integer format-control letters for values
that are outside the range of a C `long' integer, `gawk' switches to the
`%g' format specifier. Other versions of `awk' may print invalid values
or do something else entirely.  (d.c.)