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     PRINTF(3S)                                             PRINTF(3S)

     NAME
          printf, fprintf, sprintf - formatted output conversion

     SYNOPSIS
          #include <stdio.h>

          printf(format [, arg ] ...  )
          char *format;

          fprintf(stream, format [, arg ] ...  )
          FILE *stream;
          char *format;

          sprintf(s, format [, arg ] ...  )
          char *s, format;

     DESCRIPTION
          Printf places output on the standard output stream stdout.
          Fprintf places output on the named output stream. Sprintf
          places `output' in the string s, followed by the character
          `\0'.

          Each of these functions converts, formats, and prints its
          arguments after the first under control of the first argu-
          ment.  The first argument is a character string which con-
          tains two types of objects: plain characters, which are sim-
          ply copied to the output stream, and conversion specifica-
          tions, each of which causes conversion and printing of the
          next successive arg printf.

          Each conversion specification is introduced by the character
          %.  Following the %, there may be

          -    an optional minus sign `-' which specifies left
               adjustment of the converted value in the indicated
               field;

          -    an optional digit string specifying a field width; if
               the converted value has fewer characters than the field
               width it will be blank-padded on the left (or right, if
               the left-adjustment indicator has been given) to make
               up the field width; if the field width begins with a
               zero, zero-padding will be done instead of blank-
               padding;

          -    an optional period `.'  which serves to separate the
               field width from the next digit string;

          -    an optional digit string specifying a precision which
               specifies the number of digits to appear after the

     PRINTF(3S)                                             PRINTF(3S)

               decimal point, for e- and f-conversion, or the maximum
               number of characters to be printed from a string;

          -    the character l specifying that a following d, o, x, or
               u corresponds to a long integer arg. (A capitalized
               conversion code accomplishes the same thing.)

          -    a character which indicates the type of conversion to
               be applied.

          A field width or precision may be `*' instead of a digit
          string.  In this case an integer arg supplies the field
          width or precision.

          The conversion characters and their meanings are

          dox  The integer arg is converted to decimal, octal, or hex-
               adecimal notation respectively.

          f    The float or double arg is converted to decimal nota-
               tion in the style `[-]ddd.ddd' where the number of d's
               after the decimal point is equal to the precision spec-
               ification for the argument.  If the precision is miss-
               ing, 6 digits are given; if the precision is explicitly
               0, no digits and no decimal point are printed.

          e    The float or double arg is converted in the style
               `[-]d.ddde±dd' where there is one digit before the dec-
               imal point and the number after is equal to the preci-
               sion specification for the argument; when the precision
               is missing, 6 digits are produced.

          g    The float or double arg is printed in style d, in style
               f, or in style e, whichever gives full precision in
               minimum space.

          c    The character arg is printed.  Null characters are
               ignored.

          s    Arg is taken to be a string (character pointer) and
               characters from the string are printed until a null
               character or until the number of characters indicated
               by the precision specification is reached; however if
               the precision is 0 or missing all characters up to a
               null are printed.

          u    The unsigned integer arg is converted to decimal and
               printed (the result will be in the range 0 to 65535).

          %    Print a `%'; no argument is converted.

          In no case does a non-existent or small field width cause

     PRINTF(3S)                                             PRINTF(3S)

          truncation of a field; padding takes place only if the spec-
          ified field width exceeds the actual width.  Characters gen-
          erated by printf are printed by putc(3).

          Examples
          To print a date and time in the form `Sunday, July 3,
          10:02', where weekday and month are pointers to null-
          terminated strings:

               printf("%s, %s %d, %02d:%02d", weekday, month, day,
                    hour, min);

          To print pi to 5 decimals:

               printf("pi = %.5f", 4*atan(1.0));

     SEE ALSO
          putc(3), scanf(3), ecvt(3)

     BUGS
          Very wide fields (>128 characters) fail.