已解决
可以实现，如下例：int max(int a,int b);
int(*pmax)(int a, int b);
int x,y,z;
pmax=max;
printf("input two numbers:\n");
scanf("%d%d",&x,&y);
z=(*pmax)(x,y);
int(*pmax)(int a, int b);
int x,y,z;
pmax=max;
printf("input two numbers:\n");
scanf("%d%d",&x,&y);
z=(*pmax)(x,y);