printf, fprintf, sprintf, snprintf, vprintf, vfprintf, vsprintf,
vsnprintf - formatted output conversion
int printf(const char *format [, arg] ...);
int fprintf(FILE *stream, const char *format [, arg] ...);
int sprintf(char *s, const char *format [, arg] ...);
int snprintf(char *s, size_t n, const char *format [, arg] ...);
int vprintf(const char *format, va_list args);
int vfprintf(FILE *stream, const char *format, va_list args);
int vsprintf(char *s, const char *format, va_list args);
int vsnprintf(char *s, size_t n, const char *format, va_list args);
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'. Snprintf (Minix-vmd only) is
like sprintf except that no more than n-1 characters are written to s
followed by a `\0'.
The v*printf functions can be used to make functions like the first four
by using the stdarg(3) method to process the argument.
Each of these functions converts, formats, and prints its arguments after
the first under control of the first argument. The first argument is a
character string which contains two types of objects: plain characters,
which are simply copied to the output stream, and conversion
specifications, each of which causes conversion and printing of the next
Each conversion specification is introduced by the character %. The
remainder of the conversion specification includes in the following order
o Zero or more of following flags:
o a `#' character specifying that the value should be converted to an
``alternate form''. For c, d, s, and u conversions, this option has
no effect. For o conversions, the precision of the number is
increased to force the first character of the output string to a
zero. For x(X) conversion, a non-zero result has the string 0x(0X)
prepended to it. For e, E, f, g, and G conversions, the result will
always contain a decimal point, even if no digits follow the point
(normally, a decimal point only appears in the results of those
conversions if a digit follows the decimal point). For g and G
conversions, trailing zeros are not removed from the result as they
would otherwise be.
o a minus sign `-' which specifies left adjustment of the converted
value in the indicated field;
o a `+' character specifying that there should always be a sign placed
before the number when using signed conversions.
o a space specifying that a blank should be left before a positive
number during a signed conversion. A `+' overrides a space if both
o 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;
o an optional period `.' which serves to separate the field width
from the next digit string;
o an optional digit string specifying a precision 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
o the character l specifying that a following d, o, x, or u
corresponds to a long integer arg.
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 arg supplies the field width or precision.
The conversion characters and their meanings are
dox The integer arg is converted to decimal, octal, or hexadecimal
X Like x, but use upper case instead of lower case.
f The float or double arg is converted to decimal notation 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
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 decimal point and the number
after is equal to the precision 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.
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
u The unsigned integer arg is converted to decimal and printed.
% 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 printf are printed by putc(3).
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));
putc(3), scanf(3), ecvt(3), stdarg(3).