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If the program was invoked with any command-line arguments, it can
access them through the arguments of main
, argc
and
argv
. (You can give these arguments any names, but the names
argc
and argv
are customary.)
The value of argv
is an array containing all of the
command-line arguments as strings, with the name of the command
invoked as the first string. argc
is an integer that says how
many strings argv
contains. Here is an example of accessing
the command-line parameters, retrieving the program’s name and
checking for the standard --version and --help options:
#include <string.h> /* Declare strcmp
. */
int
main (int argc, char *argv[])
{
char *program_name = argv[0];
for (int i = 1; i < argc; i++)
{
if (!strcmp (argv[i], "--version"))
{
/* Print version information and exit. */
…
}
else if (!strcmp (argv[i], "--help"))
{
/* Print help information and exit. */
…
}
}
…
}