Matches a fixed number of characters. If you specify a maximum field
width (see below), that is how many characters will be matched;
otherwise, %c matches one character. This conversion does not
append a null character to the end of the text it reads, as does the
%s conversion. It also does not skip whitespace characters, but
reads precisely the number of characters it was told to, or generates a
matching error if it cannot.
d
Matches an optionally signed decimal integer, containing the
following sequence:
An optional plus or minus sign (+ or -).
One or more decimal digits.
Note that %d and %i are not synonymous for scanf,
as they are for printf.
e
Matches an optionally signed floating-point number, containing the
following sequence:
An optional plus or minus sign (+ or -).
A floating-point number in decimal or hexadecimal format.
The decimal format is a sequence of one or more decimal digits,
optionally containing a decimal point character (usually .),
followed by an optional exponent part, consisting of a character
e or E, an optional plus or minus sign, and a sequence of
decimal digits.
The hexadecimal format is a 0x or 0X, followed by a
sequence of one or more hexadecimal digits, optionally containing a
decimal point character, followed by an optional binary-exponent part,
consisting of a character p or P, an optional plus or
minus sign, and a sequence of digits.
E
Same as e.
f
Same as e.
g
Same as e.
G
Same as e.
i
Matches an optionally signed integer, containing the following sequence:
An optional plus or minus sign (+ or -).
A string of characters representing an unsigned integer.
If the string begins with 0x or 0X, the number is
assumed to be in hexadecimal format, and the rest of the string must contain
hexadecimal digits.
Otherwise, if the string begins with 0, the number is
assumed to be in octal format (base eight), and the rest of the
string must contain octal digits.
Otherwise, the number is assumed to be in decimal format, and the rest
of the string must contain decimal digits.
Note that %d and %i are not synonymous for scanf,
as they are for printf. You can print integers in this syntax
with printf by using the # flag character with the %x
or %d output conversions. (See printf.)
s
Matches a string of non-whitespace characters. It skips initial
whitespace, but stops when it meets more whitespace after it has read
something. It stores a null character at the end of the text that it
reads, to mark the end of the string. (See String overflows with scanf, for a warning about using this conversion.)
x
Matches an unsigned integer in hexadecimal format. The string matched
must begin with 0x or 0X, and the rest of the string must
contain hexadecimal digits.
X
Same as x.
[
Matches a string containing an arbitrary set of characters. For
example, %12[0123456789] means to read a string with a maximum
field width of 12, containing characters from the set 0123456789
-- in other words, twelve decimal digits. An embedded -
character means a range of characters; thus %12[0-9] means the
same thing as the last example. Preceding the characters in the square
brackets with a caret (^) means to read a string not
containing the characters listed. Thus, %12[^0-9] means to read
a twelve-character string not containing any decimal digit.
(See String overflows with scanf, for a warning about using this
conversion.)
%
Matches a percent sign. Does not correspond to an argument, and does
not permit flags, field width, or type modifier to be specified (see
below).
In between the percent sign (%) and the input conversion
character, you can place some combination of the following modifiers, in
sequence. (Note that the percent sign conversion (%%) doesn't
use arguments or modifiers.)
An optional * flag. This flag specifies that a match should be made
between the conversion specifier and an item in the input stream, but
that the value should not then be assigned to an argument.
An optional a flag, valid with string conversions only.
This is a GNU extension to scanf that requests allocation of a
buffer long enough to safely store the string that was
read. (See String overflows with scanf, for information on how to use
this flag.)
An optional ' flag. This flag specifies that the number read will be grouped
according to the rules currently specified on your system. For example,
in the United States, this usually means that 1,000 will be read
as one thousand.
An optional decimal integer that specifies the maximum field width.
The scanf function will stop reading characters from the input stream
either when this maximum is reached, or when a non-matching character is read,
whichever comes first. Discarded initial whitespace does not count toward
this width; neither does the null character stored by string input conversions
to mark the end of the string.
An optional type modifier character from the following table.
(The default type of the corresponding argument is int * for the
%d and %i conversions, unsigned int * for %x
and %X, and float * for %e and its synonyms. You can use these
type modifiers to specify otherwise.)
h
Specifies that the argument to which the value read should be assigned is
of type short int * or unsigned short int *. Valid for the
%d and %i conversions.
l
For the %d and %i conversions, specifies that the argument
to which the value read should be assigned is of type long int *
or unsigned long int *. For the %e conversion and its
synonyms, specifies that the argument is of type double *.
L
For the %d and %i conversions, specifies that the argument
to which the value read should be assigned is of type long long int *
or unsigned long long int *. On systems that do not have
extra-long integers, this has the same effect as l.
For the %e conversion and
its synonyms, specifies that the argument is of type long double
*.
ll
Same as L, for the %d and %i conversions.
q
Same as L, for the %d and %i conversions.
z
Specifies that the argument to which the value read should be assigned
is of type size_t. (The size_t type is used to specify
the sizes of blocks of memory, and many functions in this chapter use
it.) Valid for the %d and %i conversions.
