// Demonstrates structs and union types in C
// Compile: gcc union3.c
// Execute: a.out
//
#include <stdio.h>
#include <string.h>
int main(){
   typedef enum {CASH, CHECK, CREDIT}  payments;


    // Declare a struct, comparable to a record
    // varData is a union which has 4 names for the same field
    struct transaction
    {
        payments kind;
        int amount;
            
        union  // Share space
        {
            //int discount;
            double discount;
            long checkNumber;
            char cardNumber[6];
        } varData;

        char expireDate[4];  // Only for kind=CREDIT
    };
    
     struct transaction myTrans;

    myTrans.kind = CASH;

    myTrans.amount = 3;
    printf("amount is %d\n\n", myTrans.amount);    // 3

    myTrans.varData.discount = 2.5;
    printf("discount should be 2.5 and it is %f\n", myTrans.varData.discount);    // ???

    //  Not type safe

    strcpy(myTrans.expireDate ,"0120");
    printf("ExpireDate for a cash: %s\n", myTrans.expireDate);    // ???

    myTrans.varData.checkNumber = 1234000;
    printf("checkNumber should be 1234000 and it is %d\n\n", 
                myTrans.varData.checkNumber);    // ???

    printf("discount should be 2.5 and it is %f\n", myTrans.varData.discount);    // ???
    
    printf("discount as an int is %d\n", myTrans.varData.discount);    // ???
    printf("checkNumber as a float is %f\n", myTrans.varData.checkNumber);    // ???
}
//  amount is 3
//  
//  discount should be 2.5 and it is 2.500000
//  checkNumber should be 1234000 and it is 1234000
//  
//  discount should be 2.5 and it is 2.500000
//  discount as an int is 1234000
//  checkNumber as a float is 2.500000