printf

From 7e0f021a9aec35fd8e6725e87e3313b101d26f5e Mon Sep 17 00:00:00 2001 From: Tobias Klauser Date: Sun, 27 Jan 2008 11:37:44 +0100 Subject: Initial import (2.0.2-6) --- reference/C/MAN/printf.htm | 362 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 362 insertions(+) create mode 100644 reference/C/MAN/printf.htm (limited to 'reference/C/MAN/printf.htm') diff --git a/reference/C/MAN/printf.htm b/reference/C/MAN/printf.htm new file mode 100644 index 0000000..cb8bf95 --- /dev/null +++ b/reference/C/MAN/printf.htm @@ -0,0 +1,362 @@ +printf + +
+
+
+
+PRINTF(3)           Linux Programmer's Manual           PRINTF(3)
+
+
+NAME
+       printf,  fprintf,  sprintf,  vprintf, vfprintf, vsprintf -
+       formatted output conversion
+
+SYNOPSIS
+       #include <stdio.h>
+
+       int printf( const char *format, ...);
+       int fprintf( FILE *stream, const char *format, ...);
+       int sprintf( char *str, const char *format, ...);
+
+       #include <stdarg.h>
+
+       int vprintf( const char *format, va_list ap);
+       int vfprintf( FILE *stream, const  char  *format,  va_list
+       ap);
+       int vsprintf( char *str, char *format, va_list ap);
+
+DESCRIPTION
+       The  printf  family of functions produces output according
+       to a format as described below.  Printf and vprintf  write
+       output  to stdout, the standard output stream; fprintf and
+       vfprintf write output to the given output stream; sprintf,
+       and  vsprintf  write  to  the character string str.  These
+       functions write the output under the control of  a  format
+       string  that  specifies how subsequent arguments (or argu-
+       ments accessed via the variable-length argument facilities
+       of  stdarg(3)  are  converted for output.  These functions
+       return the number of characters printed (not including the
+       trailing `\0' used to end output to strings).
+
+       The  format string is composed of zero or more directives:
+       ordinary characters (not %), which are copied unchanged to
+       the  output stream; and conversion specifications, each of
+       which results in fetching zero or  more  subsequent  argu-
+       ments.  Each conversion specification is introduced by the
+       character  %.   The  arguments  must  correspond  properly
+       (after  type  promotion)  with  the  conversion specifier.
+       After the %, the following appear in sequence:
+
+       o      Zero or more of the following flags:
+
+              #      specifying that the  value  should  be  con-
+                     verted  to an ``alternate form''.  For c, d,
+                     i, n, p, s, and u conversions,  this  option
+                     has  no effect.  For o conversions, the pre-
+                     cision of the number is increased  to  force
+                     the  first character of the output string to
+                     a zero (except if a zero  value  is  printed
+                     with  an explicit precision of zero).  For x
+                     and X conversions, a non-zero result has the
+                     string  `0x'  (or  `0X'  for  X conversions)
+                     prepended to it.  For e, E, f, g, and G con-
+                     versions,  the  result will always contain a
+
+
+
+BSD MANPAGE              29 November 1993                       1
+
+
+
+
+
+PRINTF(3)           Linux Programmer's Manual           PRINTF(3)
+
+
+                     decimal point, even if no digits  follow  it
+                     (normally,  a  decimal  point appears in the
+                     results of those conversions only if a digit
+                     follows).  For g and G conversions, trailing
+                     zeros are not removed  from  the  result  as
+                     they would otherwise be.
+
+              0      specifying  zero  padding.   For all conver-
+                     sions  except  n,  the  converted  value  is
+                     padded  on  the  left with zeros rather than
+                     blanks.  If a  precision  is  given  with  a
+                     numeric  conversion  (d,  i, o, u, i, x, and
+                     X), the 0 flag is ignored.
+
+              -      (a negative field width flag) indicates  the
+                     converted  value  is  to be left adjusted on
+                     the field boundary.  Except  for  n  conver-
+                     sions,  the converted value is padded on the
+                     right with blanks, rather than on  the  left
+                     with  blanks or zeros.  A - overrides a 0 if
+                     both are given.
+
+                     (a space) specifying that a blank should  be
+                     left  before a positive number produced by a
+                     signed conversion (d, e, E, f, g, G, or  i).
+
+              +      specifying  that  a  sign  always  be placed
+                     before a number produced by a signed conver-
+                     sion.   A  +  overrides  a space if both are
+                     used.
+
+       o      An optional decimal digit string specifying a mini-
+              mum  field width.  If the converted value has fewer
+              characters than the field width, it will be  padded
+              with  spaces  on  the  left (or right, if the left-
+              adjustment flag has been given)  to  fill  out  the
+              field width.
+
+       o      An  optional  precision,  in  the  form of a period
+              (`.')  followed by an optional  digit  string.   If
+              the digit string is omitted, the precision is taken
+              as zero.  This gives the minimum number  of  digits
+              to appear for d, i, o, u, x, and X conversions, the
+              number of digits to appear after the  decimal-point
+              for  e, E, and f conversions, the maximum number of
+              significant digits for g and G conversions, or  the
+              maximum  number  of characters to be printed from a
+              string for s conversions.
+
+       o      The optional character h, specifying that a follow-
+              ing d, i, o, u, x, or X conversion corresponds to a
+              short int or unsigned short int argument, or that a
+              following  n conversion corresponds to a pointer to
+              a short int argument.
+
+
+
+BSD MANPAGE              29 November 1993                       2
+
+
+
+
+
+PRINTF(3)           Linux Programmer's Manual           PRINTF(3)
+
+
+       o      The optional character l (ell)  specifying  that  a
+              following d, i, o, u, x, or X conversion applies to
+              a pointer to a long int or unsigned long int  argu-
+              ment,  or that a following n conversion corresponds
+              to a pointer to a long int argument.
+
+       o      The character L specifying that a following  e,  E,
+              f,  g, or G conversion corresponds to a long double
+              argument.
+
+       o      A character that specifies the type  of  conversion
+              to be applied.
+
+       A  field  width or precision, or both, may be indicated by
+       an asterisk `*' instead of a digit string.  In this  case,
+       an  int argument supplies the field width or precision.  A
+       negative field width is treated as a left adjustment  flag
+       followed  by  a positive field width; a negative precision
+       is treated as though it were missing.
+
+       The conversion specifiers and their meanings are:
+
+       diouxX The int (or appropriate variant) argument  is  con-
+              verted  to signed decimal (d and i), unsigned octal
+              (o, unsigned decimal (u, or unsigned hexadecimal (x
+              and X) notation.  The letters abcdef are used for x
+              conversions; the letters ABCDEF are used for X con-
+              versions.  The precision, if any, gives the minimum
+              number of digits that must appear; if the converted
+              value  requires  fewer  digits, it is padded on the
+              left with zeros.
+
+       DOU    The long int argument is converted to signed  deci-
+              mal, unsigned octal, or unsigned decimal, as if the
+              format had been ld, lo, or lu respectively.   These
+              conversion  characters  are  deprecated,  and  will
+              eventually disappear.
+
+       eE     The double argument is rounded and converted in the
+              style  [-]d.dddedd  where there is one digit before
+              the decimal-point character and the number of  dig-
+              its after it is equal to the precision; if the pre-
+              cision is missing, it is taken as 6; if the  preci-
+              sion  is  zero, no decimal-point character appears.
+              An E conversion uses the letter E (rather  than  e)
+              to  introduce  the  exponent.   The exponent always
+              contains at least two digits; if the value is zero,
+              the exponent is 00.
+
+       f      The  double  argument  is  rounded and converted to
+              decimal notation in the style [-]ddd.ddd, where the
+              number  of digits after the decimal-point character
+              is equal to the precision  specification.   If  the
+              precision  is  missing,  it  is  taken as 6; if the
+
+
+
+BSD MANPAGE              29 November 1993                       3
+
+
+
+
+
+PRINTF(3)           Linux Programmer's Manual           PRINTF(3)
+
+
+              precision  is  explicitly  zero,  no  decimal-point
+              character  appears.  If a decimal point appears, at
+              least one digit appears before it.
+
+       g      The double argument is converted in style  f  or  e
+              (or  E for G conversions).  The precision specifies
+              the number of significant digits.  If the precision
+              is missing, 6 digits are given; if the precision is
+              zero, it is treated as 1.  Style e is used  if  the
+              exponent  from  its  conversion  is less than -4 or
+              greater than or equal to the  precision.   Trailing
+              zeros  are  removed from the fractional part of the
+              result; a decimal point appears only if it is  fol-
+              lowed by at least one digit.
+
+       c      The  int argument is converted to an unsigned char,
+              and the resulting character is written.
+
+       s      The ``char *'' argument is expected to be a pointer
+              to  an  array  of  character  type  (pointer  to  a
+              string).  Characters from the array are written  up
+              to (but not including) a terminating NUL character;
+              if a precision is specified, no more than the  num-
+              ber  specified  are  written.   If  a  precision is
+              given, no null character need be  present;  if  the
+              precision  is not specified, or is greater than the
+              size of the array, the array must contain a  termi-
+              nating NUL character.
+
+       p      The  ``void *'' pointer argument is printed in hex-
+              adecimal (as if by %#x or %#lx).
+
+       n      The number of characters written so far  is  stored
+              into  the  integer  indicated  by the ``int *'' (or
+              variant) pointer argument.   No  argument  is  con-
+              verted.
+
+       %      A  `%'  is  written.  No argument is converted. The
+              complete conversion specification is `%%'.
+
+       In no case does a non-existent or small field width  cause
+       truncation  of  a  field; if the result of a conversion is
+       wider than the field width, the field is expanded to  con-
+       tain the conversion result.
+
+
+EXAMPLES
+       To  print  a  date  and  time in the form `Sunday, July 3,
+       10:02', where weekday and month are pointers to strings:
+              #include <stdio.h>
+              fprintf(stdout, "%s, %s %d, %.2d:%.2d\n",
+                   weekday, month, day, hour, min);
+
+       To print to five decimal places:
+
+
+
+BSD MANPAGE              29 November 1993                       4
+
+
+
+
+
+PRINTF(3)           Linux Programmer's Manual           PRINTF(3)
+
+
+              #include <math.h>
+              #include <stdio.h>
+              fprintf(stdout, "pi = %.5f\n", 4 * atan(1.0));
+
+       To allocate a 128 byte string and print into it:
+              #include <stdio.h>
+              #include <stdlib.h>
+              #include <stdarg.h>
+              char *newfmt(const char *fmt, ...)
+              {
+                        char *p;
+                        va_list ap;
+                        if ((p = malloc(128)) == NULL)
+                             return (NULL);
+                        va_start(ap, fmt);
+                        (void) vsnprintf(p, 128, fmt, ap);
+                        va_end(ap);
+                        return (p);
+              }
+
+
PRINTF(3) Linux Programmer's Manual PRINTF(3) +

NAME +

SYNOPSIS +

DESCRIPTION +

BSD MANPAGE 29 November 1993 1 +

PRINTF(3) Linux Programmer's Manual PRINTF(3) +

BSD MANPAGE 29 November 1993 2 +

PRINTF(3) Linux Programmer's Manual PRINTF(3) +

BSD MANPAGE 29 November 1993 3 +

PRINTF(3) Linux Programmer's Manual PRINTF(3) +

EXAMPLES +

BSD MANPAGE 29 November 1993 4 +

PRINTF(3) Linux Programmer's Manual PRINTF(3) +

SEE ALSO +

STANDARDS +

BUGS +

BSD MANPAGE 29 November 1993 5 +
