• 1Parameters
• 2Return value
• 3Complexity
• 4Notes
• 5Example
• 6References
• 7See also

Matches acharacter or a sequence ofcharacters.

• If a width specifier is used, matches exactlywidth characters (the argument must be a pointer to an array with sufficient room).
• Unlike %s and %[, does not append the null character to the array.

Matches a sequence of non-whitespace characters (astring).

• If width specifier is used, matches up towidth or until the first whitespace character, whichever appears first.
• Always stores a null character in addition to the characters matched (so the argument array must have room for at leastwidth+1 characters).

Matches a non-empty sequence of character fromset of characters.

• If the first character of the set is^, then all characters not in the set are matched.
• If the set begins with] or^] then the] character is also included into the set.
• It is implementation-defined whether the character- in the non-initial position in the scanset may be indicating a range, as in[0-9].
• If width specifier is used, matches only up towidth.
• Always stores a null character in addition to the characters matched (so the argument array must have room for at leastwidth+1 characters).

Matches adecimal integer.

• The format of the number is the same as expected bystrtol with the value10 for thebase argument.

Matches aninteger.

• The format of the number is the same as expected bystrtol with the value​0​ for thebase argument (base is determined by the first characters parsed).

Matches an unsigneddecimal integer.

• The format of the number is the same as expected bystrtoul with the value10 for thebase argument.

Matches an unsignedoctal integer.

• The format of the number is the same as expected bystrtoul with the value8 for thebase argument.

Matches an unsignedhexadecimal integer.

• The format of the number is the same as expected bystrtoul with the value16 for thebase argument.

Returns thenumber of characters read so far.

• No input is consumed. Does not increment the assignment count.
• If the specifier has assignment-suppressing operator defined, the behavior is undefined.

Matches afloating-point number.

• The format of the number is the same as expected bystrtof.

Matches implementation defined character sequence defining apointer.

• printf family of functions should produce the same sequence using%p format specifier.

For every conversion specifier other thann, the longest sequence of input characters which does not exceed any specified field width and which either is exactly what the conversion specifier expects or is a prefix of a sequence it would expect, is what's consumed from the stream. The first character, if any, after this consumed sequence remains unread. If the consumed sequence has length zero or if the consumed sequence cannot be converted as specified above, the matching failure occurs unless end-of-file, an encoding error, or a read error prevented input from the stream, in which case it is an input failure.

All conversion specifiers other than[,c, andn consume and discard all leading whitespace characters (determined as if by callingisspace) before attempting to parse the input. These consumed characters do not count towards the specified maximum field width.

The conversion specifierslc,ls, andl[ perform multibyte-to-wide character conversion as if by callingmbrtowc with anmbstate_t object initialized to zero before the first character is converted.

The conversion specifierss and[ always store the null terminator in addition to the matched characters. The size of the destination array must be at least one greater than the specified field width. The use of%s or%[, without specifying the destination array size, is as unsafe asgets.

The correct conversion specifications for thefixed-width integer types (int8_t, etc) are defined in the header<inttypes.h> (althoughSCNdMAX,SCNuMAX, etc is synonymous with%jd,%ju, etc).

There is asequence point after the action of each conversion specifier; this permits storing multiple fields in the same “sink” variable.

When parsing an incomplete floating-point value that ends in the exponent with no digits, such as parsing"100er" with the conversion specifier%f, the sequence"100e" (the longest prefix of a possibly valid floating-point number) is consumed, resulting in a matching error (the consumed sequence cannot be converted to a floating-point number), with"r" remaining. Some existing implementations do not follow this rule and roll back to consume only"100", leaving"er", e.g.,glibc bug 1765.

If a conversion specification is invalid, the behavior is undefined.