It's a decimal floating point specifier with a precision sub-specifier.
this post was submitted on 25 Sep 2023
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Example with pi.
#define PI 3.1415926
int main() {
printf("%.2f", PI); // prints 3.14
return 0;
}
%.2f% means it will format to two decimal places max. So 5.877 will format as 5.88 and 1 will format as 1.00.
man printf
This is the way
If you want multi-line code, you need to put it like this:
For these kinds of questions, your best friend is the documentation. In particular, a man 'printf(3)' yields:
Format of the format string
The format string is a character string, beginning and ending in its initial shift state, if any. The format string is composed of zero or more directives: ordinary characters (not %), which are copied unchanged to the output stream; and conversion specifications, each of which results in fetching zero or more subsequent arguments. Each conversion specification is introduced by the character %, and ends with a conversion specifier. In between there may be (in this order) zero or more flags, an optional minimum field width, an optional precision and an optional length modifier.
The overall syntax of a conversion specification is:
%[$][flags][width][.precision][length modifier]conversion
Wouldn't man 3 printf do the same thing without the quotes?
Yup that definitely does the same thing.
If anyone else is wondering why the 3 is there, it's because usually you won't find just one printf. You have the printf user command, the printf function from the standard C library, and POSIX manual entries for both the printf user command and C function. The id number is then an identifier for the corresponding section of the printf entry, and you can list all of them by doing a man -f printf.
The id number is then an identifier for the corresponding section of the printf entry,
Nit: 3 is the manual section in which to look for the named entry (aka page), not a section of the entry.
Wrote it in an awkward way but yeah I meant to say the section where you can find the corresponding entry 😬
Awesome, I think I'm gonna consider aliasing man to man -f lol. Can you think of any compelling reason not to?
Actually, nevermind, I misunderstood you. -f just lists the pages, it doesn't print all of their content.
Wait, you can use man on C functions?
On libc functions yes. Maybe on some from other libs, if they provide man pages.
That's nice.
Yup! Try also man malloc 😁
Nice :)
You can if you have those man pages installed.
You might also enjoy man ascii, man operator, or even man intro.
Unfortunately, there are still some gaps:
$ man love
No manual entry for loveBack in my day, MS-DOS let you use HELP on QBASIC commands.
This formats the number with 2 decimals behind the dot.
%.2f will format your number rounded to two decimal places. So if you had 1 / 3 it would come out as 0.33 instead of 0.333333
% is the placeholder for the value
.2 tells it 'two spaces after the decimal'
f tells it that the placeholder is a float