2.11BSD/man/cat3/fprintf.0
PRINTF(3S) UNIX Programmer's Manual PRINTF(3S)
NAME
printf, fprintf, sprintf, vfprintf, vsprintf - formatted
output conversion
SYNOPSIS
#include <stdio.h>
char *printf(format [, arg ] ... )
char *format;
char *fprintf(stream, format [, arg ] ... )
FILE *stream;
char *format;
int sprintf(s, format [, arg ] ... )
char *s, *format;
#include <varargs.h>
char *vprintf(format, args)
char *format;
va_list args;
char *vfprintf(stream, format, args)
FILE *stream;
char *format;
va_list args;
int vsprintf(s, format, args)
char *s, *format;
va_list args;
DESCRIPTION
_P_r_i_n_t_f places output on the standard output stream stdout.
_F_p_r_i_n_t_f places output on the named output _s_t_r_e_a_m. _S_p_r_i_n_t_f
places `output' in the string _s, followed by the character
`\0'. Alternate forms, in which the arguments have already
been captured using the variable-length argument facilities
of _v_a_r_a_r_g_s(3), are available under the names _v_p_r_i_n_t_f,
_v_f_p_r_i_n_t_f, and _v_s_p_r_i_n_t_f.
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 _a_r_g _p_r_i_n_t_f.
Each conversion specification is introduced by the character
%. The remainder of the conversion specification includes
in the following order
Printed 11/26/99 August 10, 1988 1
PRINTF(3S) UNIX Programmer's Manual PRINTF(3S)
o+ a minus sign `-' which specifies _l_e_f_t _a_d_j_u_s_t_m_e_n_t of the
converted value in the indicated field;
o+ an optional digit string specifying a _f_i_e_l_d _w_i_d_t_h; 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;
o+ an optional period, followed by an optional digit
string giving a _p_r_e_c_i_s_i_o_n which specifies the number of
digits to appear after the decimal point, for e- and
f-conversion, or the maximum number of characters to be
printed from a string;
o+ the character l specifying that a following d, o, x, or
u corresponds to a long integer _a_r_g;
o+ 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 _a_r_g supplies the field
width or precision.
The conversion characters and their meanings are
dox The integer _a_r_g is converted to signed decimal,
unsigned octal, or unsigned hexadecimal notation
respectively.
f The float or double _a_r_g 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
specification for the argument. If the precision is
missing, 6 digits are given; if the precision is expli-
citly 0, no digits and no decimal point are printed.
e The float or double _a_r_g is converted in the style
`[-]d.ddde+_dd' where there is one digit before the
decimal point and the number after is equal to the pre-
cision specification for the argument; when the preci-
sion is missing, 6 digits are produced.
g The float or double _a_r_g is printed in style d, in style
f, or in style e, whichever gives full precision in
minimum space.
c The character _a_r_g is printed.
Printed 11/26/99 August 10, 1988 2
PRINTF(3S) UNIX Programmer's Manual PRINTF(3S)
s _A_r_g 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 _a_r_g is converted to decimal and
printed (the result will be in the range 0 through MAX-
UINT, where MAXUINT equals 4294967295 on a VAX-11 and
65535 on a PDP-11).
% Print a `%'; no argument is converted.
In no case does a non-existent or small field width cause
truncation of a field; padding takes place only if the
specified field width exceeds the actual width. Characters
generated by _p_r_i_n_t_f are printed as by _p_u_t_c(3S).
RETURN VALUE
The functions all return the number of characters printed,
or -1 if an error occurred.
EXAMPLES
To print a date and time in the form `Sunday, July 3,
10:02', where _w_e_e_k_d_a_y and _m_o_n_t_h 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(3S), scanf(3S)
BUGS
Very wide fields (>300 characters) fail.
Only _s_p_r_i_n_t_f and _v_s_p_r_i_n_t_f return a count of characters
transferred.
The functions still supports %_D, %_O, %_U and %_X. Do not use
these formats, as they will be disappearing real soon now.
Printed 11/26/99 August 10, 1988 3