填空题 以下程序的输出结果是______。 #include＜stdio.h＞ funa(int a, int b){return a+b; } funb(int a, int b){return a-b; } sub(int(*t)(), int x, int y){return(*t)(x, y);} main() { int x, (*p)(int, int); p=funa; x=sub(p, 9, 3); x+=sub (funb, 8, 3); printf("%d/n", x);