Parameters

format

C string that contains the text to be written tostdout.
It can optionally contain embeddedformat specifiers that are replaced by the values specified in subsequent additional arguments and formatted as requested.

Aformat specifier follows this prototype:[see compatibility note below]
%[flags][width][.precision][length]specifier

Where thespecifier character at the end is the most significant component, since it defines the type and the interpretation of its corresponding argument:

specifier	Output	Example
dori	Signed decimal integer	392
u	Unsigned decimal integer	7235
o	Unsigned octal	610
x	Unsigned hexadecimal integer	7fa
X	Unsigned hexadecimal integer (uppercase)	7FA
f	Decimal floating point, lowercase	392.65
F	Decimal floating point, uppercase	392.65
e	Scientific notation (mantissa/exponent), lowercase	3.9265e+2
E	Scientific notation (mantissa/exponent), uppercase	3.9265E+2
g	Use the shortest representation:%e or%f	392.65
G	Use the shortest representation:%E or%F	392.65
a	Hexadecimal floating point, lowercase	-0xc.90fep-2
A	Hexadecimal floating point, uppercase	-0XC.90FEP-2
c	Character	a
s	String of characters	sample
p	Pointer address	b8000000
n	Nothing printed. The corresponding argument must be a pointer to asigned int. The number of characters written so far is stored in the pointed location.
%	A% followed by another% character will write a single% to the stream.	%

Theformat specifier can also contain sub-specifiers:flags,width,.precision andmodifiers (in that order), which are optional and follow these specifications:

flags	description
-	Left-justify within the given field width; Right justification is the default (seewidth sub-specifier).
+	Forces to preceed the result with a plus or minus sign (+ or-) even for positive numbers. By default, only negative numbers are preceded with a- sign.
(space)	If no sign is going to be written, a blank space is inserted before the value.
#	Used witho,x orX specifiers the value is preceeded with0,0x or0X respectively for values different than zero. Used witha,A,e,E,f,F,g orG it forces the written output to contain a decimal point even if no more digits follow. By default, if no digits follow, no decimal point is written.
0	Left-pads the number with zeroes (0) instead of spaces when padding is specified (seewidth sub-specifier).

width	description
(number)	Minimum number of characters to be printed. If the value to be printed is shorter than this number, the result is padded with blank spaces. The value is not truncated even if the result is larger.
*	Thewidth is not specified in theformat string, but as an additional integer value argument preceding the argument that has to be formatted.

.precision	description
.number	For integer specifiers (d,i,o,u,x,X):precision specifies the minimum number of digits to be written. If the value to be written is shorter than this number, the result is padded with leading zeros. The value is not truncated even if the result is longer. Aprecision of0 means that no character is written for the value0. Fora,A,e,E,f andF specifiers: this is the number of digits to be printedafter the decimal point (by default, this is 6). Forg andG specifiers: This is the maximum number of significant digits to be printed. Fors: this is the maximum number of characters to be printed. By default all characters are printed until the ending null character is encountered. If the period is specified without an explicit value forprecision,0 is assumed.
.*	Theprecision is not specified in theformat string, but as an additional integer value argument preceding the argument that has to be formatted.

Thelength sub-specifier modifies the length of the data type. This is a chart showing the types used to interpret the corresponding arguments with and withoutlength specifier (if a different type is used, the proper type promotion or conversion is performed, if allowed):

	specifiers
length	d i	u o x X	f F e E g G a A	c	s	p	n
(none)	int	unsigned int	double	int	char*	void*	int*
hh	signed char	unsigned char					signed char*
h	short int	unsigned short int					short int*
l	long int	unsigned long int		wint_t	wchar_t*		long int*
ll	long long int	unsigned long long int					long long int*
j	intmax_t	uintmax_t					intmax_t*
z	size_t	size_t					size_t*
t	ptrdiff_t	ptrdiff_t					ptrdiff_t*
L			long double

Note regarding thec specifier: it takes anint (orwint_t) as argument, but performs the proper conversion to achar value (or awchar_t) before formatting it for output.

Note: Yellow rows indicate specifiers and sub-specifiers introduced by C99. See<cinttypes> for the specifiers for extended types.

...(additional arguments)

Depending on theformat string, the function may expect a sequence of additional arguments, each containing a value to be used to replace aformat specifier in theformat string (or a pointer to a storage location, forn).
There should be at least as many of these arguments as the number of values specified in theformat specifiers. Additional arguments are ignored by the function.

Return Value

Example

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14
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/* printf example */#include <stdio.h>int main(){   printf ("Characters: %c %c \n",'a', 65);   printf ("Decimals: %d %ld\n", 1977, 650000L);   printf ("Preceding with blanks: %10d \n", 1977);   printf ("Preceding with zeros: %010d \n", 1977);   printf ("Some different radices: %d %x %o %#x %#o \n", 100, 100, 100, 100, 100);   printf ("floats: %4.2f %+.0e %E \n", 3.1416, 3.1416, 3.1416);   printf ("Width trick: %*d \n", 5, 10);   printf ("%s \n","A string");return 0;}

Characters: a ADecimals: 1977 650000Preceding with blanks:       1977Preceding with zeros: 0000001977Some different radices: 100 64 144 0x64 0144floats: 3.14 +3e+000 3.141600E+000Width trick:    10A string

Compatibility

See also

puts

Write string to stdout(function)

scanf

Read formatted data from stdin(function)

fprintf

Write formatted data to stream(function)

fwrite

Write block of data to stream(function)