Description
The printf() function writes data formated as specified in the string fmt
, to the standard output stream.
Fmt
All characters in fmt
are printed as is, except for formating directives starting with %
. Each of these directives correspond to one argument in the variable argument list. In addition to the %
, a directive contain optional flags and a conversion type.
These are the conversion types:
code | conversion | data type |
---|---|---|
d | signed decimal | int |
i | signed decimal | int |
u | unsigned decimal | int |
o | octal | int |
x | hexadecimal lower case | int |
X | hexadecimal upper case | int |
f | decimal notation | double |
F | decimal notation | double |
e | e notation | double |
E | e notation | double |
g | decimal or e notation | double |
G | decimal or e notation | double |
c | character | char |
s | string | char * |
P | address | void * |
Usage example:
#include<stdio.h> int main() { int n=5; printf("n=%d\n", n); return 0; }
Full program, strictly conforming; public domain; past reviewers: {{{past-reviewers--no-line-breaks}}}; current reviews: {{{later-reviews--"none"-or-empty}}}
Return value
If successful, the printf() function returns the number of written characters. To indicate an error, -1 is returned.
Prototype
Declared in stdio.h
The C89/C99 prototype is:
int printf(const char *fmt, ...);