Question

Suppose I have an array of size 10 characters (memset to 0), which I am passing to strncat as destination, and in source I am passing a string which is say 20 characters in length (null terminated), now should I pass the ‘count’ as 10 or 9?

The doubt is, does strncpy considers the ‘count’ as size of destination buffer or does it just copy 10 characters to the destination and then append a NULL terminating character in the 11th position.

Sorry if the question appears too trivial, but I was unable to make this out from the help documentation of strncpy.

Answer 1

$ man strncat

If src contains n or more characters, strncat() writes  n+1  characters
to  dest  (n  from src plus the terminating null byte).  Therefore, the
size of dest must be at least strlen(dest)+n+1

$