printf.3s (2010 09)

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printf(3S) printf(3S)

NAME

printf(), fprintf(), sprintf(), snprintf() - print formatted output

SYNOPSIS

#include <stdio.h>

int printf(const char *__restrict format, /* [arg,] */ ...);

int fprintf(FILE *__restrict stream, const char *__restrict format,

/* [arg,] */ ...);

int sprintf(char *__restrict s, const char *__restrict format,

/* [arg,] */ ...);

int snprintf(char *__restrict s, size_t maxsize,

const char *__restrict format, /* [arg,] */ ...);

DESCRIPTION

printf() places output on the standard output stream stdout .

fprintf() places output on the named output stream .

sprintf() places "output", followed by the null character (

\0), in consecutive bytes starting at *

s. It is

the user’s responsibility to ensure that enough storage is available.

snprintf() behaves like sprintf(), except that it limits the number of characters written to the

destination buffer to maxsize, including the terminating null character.

Each function converts, formats, and prints its arg s under control of the format . format is a character

string containing two types of objects: plain characters that are copied to the output stream, and conver-

sion speciﬁcations, each of which results in fetching zero or more args. The results are undeﬁned if there

are insufﬁcient args for the format. If the format is exhausted while arg s remain, excess args are

ignored.

Each conversion speciﬁcation is introduced by the character

% or %n$, where n is a decimal integer in the

range 1 through

{NL_ARGMAX} (NL_ARGMAX is deﬁned in <limits.h>). The %n

$ construction indi-

cates that this conversion should be applied to the nth argument, rather than to the next unused one.

An argument can be referenced by a

%n$ speciﬁcation more than once. The two forms of introducing a

conversion speciﬁcation, % and %n$, cannot be mixed within a single format string. When numbered

argument speciﬁcations are used, specifying the Nth argument requires that all the leading arguments,

from the ﬁrst to the (N-1)th, are speciﬁed in the format string. The results of mixing numbered and

unnumbered argument speciﬁcations in a format string are undeﬁned.

After the

% or %n$, the following appear in sequence:

1. Zero or more ﬂags, which modify the meaning of the conversion speciﬁcation.

2. An optional string of decimal digits to specify a minimum ﬁeld width in bytes. If the converted

value has fewer characters than the ﬁeld width, it is be padded on the left (or right, if the left-

adjustment ﬂag (

-), described below, has been given) to the ﬁeld width. If the ﬁeld width is

preceded by a zero, the string is right adjusted with zero-padding on the left (see the leading-

zero ﬂag, 0, described below).

3. A precision that gives the minimum number of digits to appear for the

d, i, o, u, x,orX

conversions, the number of digits to appear after the radix character for the a, e, and f

conversions, the maximum number of signiﬁcant digits for the g conversion, or the maximum

number of bytes to be printed from a string in the s conversion. The precision takes the form

of a period followed by a decimal digit string; a null digit string is treated as zero.

4. Zero or more of the following optional character speciﬁcations:

• an optional

h, specifying that a following d, i, o, u, x,orX conversion character applies

to a short integer arg

• an optional

h specifying that a following n conversion character applies to a pointer to a

short integer arg

• an optional

hh specifying that a following d, i, o, u, x or X conversion speciﬁer applies to

a signed char or unsigned char argument (the argument will have been promoted accord-

ing to the integer promotions, but its value will be converted to short or unsigned short

before printing)

HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1

Summary of content (6 pages)

PAGE 1
printf(3S) printf(3S) NAME printf(), fprintf(), sprintf(), snprintf() - print formatted output SYNOPSIS #include int printf(const char *__restrict format, /* [arg,] */ ...); int fprintf(FILE *__restrict stream, const char *__restrict format, /* [arg,] */ ...); int sprintf(char *__restrict s, const char *__restrict format, /* [arg,] */ ...); int snprintf(char *__restrict s, size_t maxsize, const char *__restrict format, /* [arg,] */ ...
PAGE 2
printf(3S) printf(3S) • an optional hh specifying that a following n conversion specifier applies to a pointer to a signed char argument • an optional hL specifying that a following a, e, f, or g conversion wide-character applies to a type extended which is the 80-bit IEEE-754 double-extended type in the Itanium architecture • an optional j specifying that a following d, i, o, u, x or X conversion specifier applies to an intmax_t or uintmax_t argument • an optional j specifying that a following n
PAGE 3
printf(3S) printf(3S) blank If the first character of a signed conversion is not a sign, a blank is prefixed to the result. This implies that if the blank and + flags both appear, the blank flag is ignored. # This flag specifies that the value is converted to an "alternate form". For c, d, i, s, n, and u conversions, the flag has no effect. For o conversion, it increases the precision to force the first digit of the result to be a zero. For x or X conversion, a nonzero result is prefixed by 0x or 0X.
PAGE 4
printf(3S) printf(3S) • Otherwise, use style e formatting with formatting precision equal to n - 1. Except if c = 0, then the digit-sequence in the exponent-part will have the value q (rather than 0), and that the exponent is always expressed with the minimum number of digits required to represent its value (the exponent never contains a leading zero).
PAGE 5
printf(3S) printf(3S) The a, e, f, and g conversions will print inf for infinity and nan for both quiet and signaling NaN values. The A, E, F, and G conversions will print INF for infinity and NAN for both quiet and signaling NaN values. For a and A conversions (on Itanium(R)-based systems), the value is correctly rounded to a hexadecimal floating point number with the given precision.
PAGE 6
printf(3S) printf(3S) [EFBIG] An attempt was made to write to a file that exceeds the process’s file size limit or the maximum file size (see ulimit (2)). [EINTR] A signal was caught during the write() system call. [EIO] The process is in a background process group and is attempting to write to its controlling terminal, TOSTOP is set, the process is neither ignoring nor blocking the SIGTTOU signal, and the process group of the process is orphaned.