What are curtailment bars on an r.c.c. slab? How does this code work: #include<stdio.h> main() {int r,c, sum; for (r=1;r<=3;r=c) {for (c=1;c<=2;c=r) {sum=r+c; printf ("r=%d c=%d sum=%d\n", r,c, sum);} printf ("%d\n", c);}}? Why does it work?