I read an article (forgot the URL), which said that argv[argc] is a NULL pointer (contains \0). To check whether if its true I wrote this code, yeah it exist. What I don't understand is, why does the OS include this NULL pointer at argv[argc]. Is it useful for something else also?
int
main (int argc, char **argv){
while (*argv)
printf ("%s\n", *argv++);
return 0;
}
The C Standard 5.1.2.2.1/2 second mark says explicitly
argv[argc] shall be a null pointer.
The C++ Standard 3.6.1/2 also says explicitly
The value of argv[argc] shall be 0.
The Standard (C99 5.1.2.2.1p2) mandates that:
If they are declared, the parameters to the main function shall obey the following constraints:
— The value of argc shall be nonnegative.
— argv[argc] shall be a null pointer.
...
The rationale for this is to provide a redundant check for the end of the argument list, on the basis of common practice (ref: Rationale for the ANSI C programming language (1990), 2.1.2.2).
