Remember that the function "main" takes optional parameters, these being common:

int main( int ac, char *av[] )

A.The variable "av" is a pointer to the command line, which can then be broken up with calls to "strtok"

B.The variable "av" has the name of the program plus the other words from the command line.

C. If there were no command line parameters, "av[0]" is NULL.

D.The value in "av[0]" is the first parameter after the program name that was typed on the command line.

E. The variable "ac" is the number of command line arguments minus one

command line arguments are used when we want to pass some parameters to the main() function from outside the program . The first argument is an integer which gives the count of the parameters . next argument is a char array which contains name of the program and other command line arguments which we need to pass to the program. We can read those parameters from that character array. In the given statement int main(int ac,char *av[]) ac indicates argument count and av char array holds the actual arguments av[0] points to the name of program and from av[1] ,they points to the actual arguments that being passed