Fabio wrote:
>I am coding a small utility for system administrator. The following command
>line options will be accepted:
>
>$apstat
>$apstat -t 1
>$apstat -n 1
>$apstat -t 2 -n 2
>$apstat -v
>$apstat -t 1 -v
>$apstat -v -t 1 -n 2
>unaccepted command line options:
>$apstat -t
>$apstat -n
>$apstat -t <<non integer value>>
>$apstat -n <<non integer value>>
with the getopt function, a colon after a flag will designate that an argument
is required. For example,
while(-1 != (choice = getopt(argc, argv, "t:n:vh")))
{
... stuff
}
would require that t and n require and argument while v and h do not. This
means that the following
command lines would be accepted:
apstat
apstat -t 1
apstat -t a
while the line apstat -t would not be accepted. If getopt encounters an option
not in the list, or if
a required argument is missing then the character `?' is returned. The
argument is returned in the
buffer `optarg'. So in your case I would do this:
while(-1 != (choice = getopt(argc, argv, "t:n:vh")))
{
switch(choice)
{
case 't':
if(IsInteger(optarg))
_t = atoi(optarg);
else
printf("Argument of t flag must be an integer");
break;
case 'n':
if(IsInteger(optarg))
_n = atoi(optarg);
else
printf("Argument of n flag must be an integer");
break
case 'v':
// Print version information??
break;
case '?':
case 'h':
// display help information
break;
}
}
In the above, I assume the existance of an IsInteger function with the
signature,
bool IsInteger(const char*);
Because I do most of my programming using C++ my implementation of IsInteger is:
bool IsInteger(const char* cp)
{
const char* ep = cp + strlen(cp);
return(std::find_if(cp, ep, std::not1(std::ptr_fun(isdigit))) == ep);
}
but the idea is the same in C - check to see if each element on optarg is an
integer
and return true if its is.
George
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