?求大神指教，哪錯了#include<stdio.h>int add(int a,int b){?int c;?c = a+b;return (c);}int sub(int d,int e){?int f;?f = d-e;return (f);}main(){?int a,b,c;?a = 20;?b = 10;??? c = add(a,b);??? printf("%d+%d=%d",a,b,c);??? int d,e,f;?d = 20;?e = 10;??? f = add(d,e);??? printf("%d-%d=%d",d,e,f);}