Trouble understanding some open source code

I'm trying to understand this open source code I found here: http://www.lysator.liu.se/~johol/fwm...MapGenerator.c.

I cannot figure out how to pass arguments to the program. I know I need to set the QUERY_STRING env var, but I don't see how. If I set it to a key value pair, the strcmp won't work. But if I just set the key well... there will be no value for the key and it still won't work!

Has anyone seen something like this before and have any idea how to pass args in?

Are you running this from the command line, or from within another program?

Code:

---

$ cat foo.c
#include<stdio.h>
#include<stdlib.h>
int main()
{
    char *Args = getenv("QUERY_STRING");
    if ( Args ) {
        printf("Got %s\n", Args );
    }
    return 0;
}
$ gcc foo.c
$ QUERY_STRING="this or that" ./a.out
Got this or that

---

I'm running from command line. I know how to set QUERY_STRING as an env var, but I don't get how the strcmps can work. See the 1st strcmp. It checks to see if Args is exactly equal to "Height". If it is, it then moves the character pointer forward past the "Height" text and reads in the rest of the string as the height value. How can that be possible? If there were more characters after "Height", the strcmp check would fail.

As far as I understand it from a quick glance.

If you pass "Height=15" as the environment var.
Args contain "Height=15"
In main the prog searches for '=' and replaces it with 0.
Args contains only "Height" and the strcmp(Args, "Height") will work
After that Args get incremented and points to "15" and sscanf will read 15 into Height.

For someone with some spare time it would be worthwhile to rewrite it in C++.