gistfile1.c

#include <stdio.h> // Import the standard I/O library
int main(int m, char**g){ // m is the argument count, g is the argument array
    int i, n, x=1; // x iterates over g, i is used in two for loops, n is used for ADDn and SUBTRACTn
    while(x<m){
        char *f=g[x++], l=*f, *a=g[x++], *b=g[f[1]&2? x++:x]; // f is the function, l is the first character thereof, a is the first operand, b is the second operand. Increment x if required.
        if (l==68) { // DIVIDE
            for(i=0; i<8; i++) putchar(a[i%4]); // Print first four characters twice
            printf(" and ");                    // Print " and "
            for(i=0; i<8; i++) putchar(a[i|4]); // Print second four characters twice
        } else for(i=0; i<8; i++)
            putchar(l&8? (i<4? a:b)[i&2? i|4:i%4]: // INTERSECT
                    l&4? i<4? a[i+4]:b[i-4]: // UNION
                    l&2? (n=f[8]-48, a[i+n<8? i+n:i]): // SUBTRACTn
                         (n=f[3]-48, a[i<n?   i:i-n])); // ADDn
	putchar(10); // Print a newline
	}
}

ACSL #2 codegolfing