How do I terminate character string array?

The following example does not work!!!

void main (void) {

int i;
char *workdays[]={"Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "" };

// notice "" - empty string at the end of array

char **work_day;

work_day=workdays;

while (*work_day) printf("%d\n", i++);

exit(1);
}

This example will print numbers from 1 to xxx instead of printing from 1 to 6.

I need explanation why "" at the end of array isn't treated as \n?

Tomislav