What does "%.*s" mean in printf?

I got a code snippet in which there is a

printf("%.*s\n")

what does the `%.*s` mean?

I don't think the code above is correct but (according to this description of [`printf()`](

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)) the `.*` means


> The width is not specified in the format string, but as an additional integer value argument preceding the argument that has to be formatted.'

So it's a string with a passable width as an argument.

See:

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> `.*` The precision is not specified in the format string, but as an additional integer value argument preceding the argument that has to be formatted.
>
> `s` String of characters

You can use an asterisk (`*`) to pass the width specifier/precision to [`printf()`](

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), rather than hard coding it into the format string, i.e.

void f(const char *str, int str_len)
{
printf("%.*s\n", str_len, str);
}

More detailed [here](

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).


> integer value or `*` that specifies minimum field width. The result is padded with space characters (by default), if required, on the left when right-justified, or on the right if left-justified. In the case when * is used, the width is specified by an additional argument of type int. If the value of the argument is negative, it results with the - flag specified and positive field width. (Note: This is the minimum width: The value is never truncated.)


> `.` followed by integer number or *, or neither that specifies precision
> of the conversion. In the case when * is used, the precision is
> specified by an additional argument of type int. If the value of this
> argument is negative, it is ignored. If neither a number nor * is
> used, the precision is taken as zero. See the table below for exact
> effects of precision.

So if we try both conversion specification

#include <stdio.h>

int main() {
int precision = 8;
int biggerPrecision = 16;
const char *greetings = "Hello world";

printf("|%.8s|\n", greetings);
printf("|%.*s|\n", precision , greetings);
printf("|%16s|\n", greetings);
printf("|%*s|\n", biggerPrecision , greetings);

return 0;
}

we get the output:

|Hello wo|
|Hello wo|
| Hello world|
| Hello world|