Thread: need help with C and a "command line?"

I am using Microsoft Visual Studio C++ 6.0 and I have a simple little code ( "dbl_out") that I can't figure out how to invoke. I can open up a workspace, a .c file, build/compile and run this program and it works, however my problem is... How do I invoke this program using redirection. My book says that it can do it four different ways: dbl_out, dbl_out < infile, dbl_out >utfile, and dbl_out <infile >outfile. What the heck does this mean? Are there other ways to get this program to work besides pressing the execute button in MSVS? Can anyone deliver insight?

Code:

#include <stdio.h>

int main (void)
{
	char c;

	while (scanf ("%c", &c) == 1) {
		printf ("%c", c);
		printf ("%c", c);
	}
	return 0;
}