1.for循环inta,b,gcd;scanf(%d%d,a,b);//设输入b不为0for(gcda%b;gcd!0;gcda%b){ab;bgcd;}gcdb;printf(GCD is: %d\n,gcd);2.while循环inta0,b0;scanf(%d %d,a,b);if(b0){printf(%d\n,a);}else{intr;while((r(a%b))!0){ab;br;}printf(%d\n,b);}return0;}