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The scanf functions deal with formatted input
conversion.
fscanf reads from stream under
control of format, and assigns converted values
through subsequent arguments, each of which must be a
pointer. It returns when format is
exhausted. fscanf returns EOF if end of file or an error occurs before any
conversion; otherwise it returns the number of input items
converted and assigned.
The format string usually contains conversion specifications, which are used to direct interpretation of input. The format string may contain:
%), which are expected to
match the next non-white space character of the input stream.%, an
optional assignment suppression character *, an
optional number specifying a maximum field width, an optional
h, l, or L indicating the
width of the target, and a conversion character.*, as in %*s,
however, the input field is simply skipped; no assignment is
made. An input field is defined as a string of non-white
space characters; it extends either to the next white space
character or until the field width, if specified, is
exhausted. This implies that scanf will read
across line boundaries to find its input, since newlines are white
space. (White space characters are blank, tab, newline,
carriage return, vertical tab, and formfeed.)
The conversion character indicates the interpretation of the input field. The corresponding argument must be a pointer. The legal conversion characters are shown below.
The conversion characters d, i,
n, o, u, and x may be
preceded by h if the argument is a pointer to
short rather than int, or by l
(letter ell) if the argument is a pointer to
long. The conversion characters e,
f, and g may be preceded by l if a
pointer to double rather than float is in
the argument list, and by L if a pointer to a
long double.
| CHARACTER | INPUT DATA; ARGUMENT TYPE | |
|---|---|---|
d |
decimal integer; int * |
|
i |
integer; int *. The integer may be in octal
(leading 0) or hexadecimal (leading 0x or
0X). |
|
o |
octal integer (with or without leading zero); int
*. |
|
u |
unsigned decimal integer; unsigned int *. |
|
x |
hexadecimal integer (with or without leading 0x or
0X); int *. |
|
c |
characters; char *. The next input
characters are placed in the indicated array, up to the number
given by the input field width; the default is 1. No
'\0' is added. The normal skip over white space
characters is suppressed in this case; to read the next non-white
space character, use %1s. |
|
s |
string of non-white space characters (not quoted); char
*, pointing to an array of characters large enough to hold
the string and terminating '\0' that will be
added. |
|
e, f, g |
floating-point number; float *. The input
format for float's is an optional sign, a string of
numbers possibly containing a decimal point, and an optional
exponent field containing an E or e
followed by a possibly signed integer. |
|
p |
pointer value as printed by printf("%p");
void *. |
|
n |
writes into the argument the number of characters read so far
by this call; int *. No input is read. The
converted item count is not incremented. |
|
[...] |
matches the longest non-empty string of input characters from
the set between brackets; char *. A
'\0' is added. []...]
includes ] in the set. |
|
[^...] |
matches the longest non-empty string of input characters
not from the set between brackets; char *.
A '\0' is added.
[^]...] includes ] in the
set. |
|
% |
literal %; no assignment is made. |
scanf(...) is identical to
fscanf(stdin,...).sscanf(s,...) is equivalent to
scanf(...) except that the input characters are
taken from the string s.| Table of Contents | Previous | Next |
Last modified: Wed May 03 13:09:25 2000