typedef

#include <stdlib.h>
#include <stdio.h>
typedef int INT;
typedef int *P; //P is a pointer which point to int type
typedef int (*Add)(int,int);
typedef int *(*Mul)(int,int);

int myAdd(int a,int b){
        return a+b;
}
int useAdd(Add add,int a,int b){
        return add(a,b);
}

int *myMul(int a,int b){
        int *p;
        int r=a*b;
        p=&r;
        return p;
}
void useMul(Mul mul,int a,int b){
        int *p;
        p=mul(a,b);
        printf("mul result=%d\n",*p);
}
int main(void){
        /* scenario one */
        INT i=10;
        printf("i=%d\n",i);

        /* scenario two */
        int a=10;
        P z=&a;
        printf("%d\n",*z);

        /* scenario three */
        int r=useAdd(myAdd,10,20);
        printf("r=%d\n",r);

        /* scenario four */
        useMul(myMul,10,2);


        exit(0);
}