Difference between (*++argv)[0] and while(c = *++argv[0])

Question

I have the following snippet of code:

int main(int argc, char *argv[])
{   

     char line[MAXLINE];
     long lineno = 0;
     int c, except = 0, number =          


        

Answer 1

yes, you are correct.

while(--argc > 0 && (*++argv)[0] == '-')

is scanning the array (of length argc) of command line arguments one by one looking for those starting with a - option prefix. For each of those:

while(c = *++argv[0])

is scanning through the set of switch characters that follow the first - in the current argument (i.e. t and n in -tn, until it hits the string null terminator \0, which terminates the while loop, since it evaluates as false.

This design allows both

myApp -t -n

and

myApp -tn

to both work and be understood as having the options t and n.