%.*s data formatter in sprintf? how it works?

[cfolk]

Hi All,

I was going through some C faqs online edition , where I saw a strange data formatter %.*s which I came across for first time , I would like to know how it works!

This question is in "comp.lang.c FAQ list · Question 13.2" which gives answer for "Why does strncpy not always place a '\0' terminator in the destination string?".



[HTML]"You can get around the problem by using strncat instead of strncpy. If the destination string starts out empty (that is, if you do *dest = '\0' first), strncat does what you probably wanted strncpy to do:

*dest = '\0';
strncat(dest, source, n);

This code copies up to n characters, and always appends a \0.

Another possibility is

sprintf(dest, "%.*s", n, source)

(though, strictly speaking, this is only guaranteed to work for n <= 509)."[/HTML]

Best regards..
Anil

[gpraghuram]

Basically the * says the number of characters placing for the following value.

Raghu

[arnaudk]

A * enables you to specify a variable field width outside the format string: printf("%.*s",2,"Hello") prints the first 2 characters: "He"