printf() usage   -   formatted printing

  printf ( "format-expression", args )                  # parens optional
  printf ("Total: %d bytes (%d files)\n", n1, n2)       # awk example
  Each %specifier in "quoted part" must have a corresponding parameter in
  the arg list. Most common %specifiers are %s(tring) and %d(ecimal).

SPECIFIERS:                                    FLAGS, WIDTH, & PRECISION
==================                             =========================
 c   ASCII character                           %[flag][width][.precis]specif
 d   decimal integer (converts to integer!)
 i   decimal integer (same; POSIX addition)    FLAGS....
 e   floating point ([-]d.precisione[+-]dd)     nil  |    print flush right|
 E   floating point ([-]d.precisionE[+-]dd)      -   |print flush left     |
 f   floating point ([-]6digit.precision)        SP  prefix %d with SPACE
 g   e or f, shortest, trailing 0's removed      +   prefix nums with + or -
 G   E or f, shortest, trailing 0's removed      0   prefix nums with zeroes
 o   unsigned octal value
 s   string                                    WIDTH: width of total field
 x   unsigned hex num, uses a-f for 10-15
 X   unsigned hex num, uses A-F for 10-15      PRECIS: num of decimal places
 %   literal percent sign                      if %f; num of digits if %d,%i

In the following examples, let %S be length(%s) and %D be length(%d or %i)

If WIDTH   > (%S|%D), the output will be padded with spaces.
If WIDTH  <= (%S|%D), the output will be printed in full (not truncated).
If PRECIS => (%S|%D), the output will be printed in full (not truncated).

If PRECIS  < %S, the string will be truncated on the right.
If PRECIS  < %D, the digits will NOT be truncated

Ex:  printf("[%-7s] [%8.3f] [%+8.3i]", "foo", "12.9", "12.9") ==
     [foo    ] [  12.900] [    +012] ==> %f(loating pt), %i(nteger truncated)
         ^^^^   ^^         ^^^^

Ex:  printf("[%8.3s] [%8.6s]", "abcde", "fghij") ==
     [     abc] [   fghij] ==> WIDTH provides padding, PREC limits chars
      ^^^^^      ^^^
Ex:  printf("[%8.3i] [%8.6i]", "12345.67", "123456789") =
     [   12345] [123456789] ==> integers printed in full, decimals truncated
      ^^^

Ex:  printf("%+*.*f", var1, var2, $3)
     Using the * inserts the value of var1 and var2 for width and precision.
--
Summary by Eric Pement