#include<stdio.h>
//1.void with no parameter  แสดงข้อมูลร้านค้า
void store_Info(){
    char storename [30]; 
    printf("Enter your store name "); //ใส่ชื่อร้าน
    scanf("%s",storename); //  %S ชื่อร้านมีหลายตัวอักษร ไม่ต้องใส่& เพราะใช้%S นอกนั้นใส่&
    printf("Store name is %s\n",storename); 
}
 
//2.return function with no parameter  คืนค่า ปีโปรโมชั่น
int promotionyear(){ 
int year ; 
printf("Enter promotion year "); 
scanf("%d",&year ); 
return year ; 
}
 
// ข้อ 3 คือ return double 
float discount1 (float totalprice){
    int choice ;
    float discount ;   
    printf("Enter your choice >>>1 is member discount 5%% >>> 2 is festival discount 10%% >>> 3 is speaial discount 15%% : "); 
    scanf("%d",&choice); 
    switch(choice){ // ข้อ 4 swith case
        case 1: 
            printf("you select member discount 5%% \n");
            discount= totalprice*0.95 ;
            break;        
        case 2 :
            printf("you select festival discount 10%% \n");
            discount= totalprice*0.90 ; 
            break; 
        case 3 :
            printf("you select special discount 15%% \n");
            discount= totalprice*0.85 ; 
            break; 
        default: 
            printf("please select again\n"); 
    }
    return discount;
} 
 
    const int secret_number= 34;
int guess_number(){  //ข้อ 5 return function with out parameter
    int guess ;
    while(1){
    printf("guess number (1-99): "); 
    scanf("%d",&guess);
 
    if (guess > secret_number){
        printf("Too many\n"); 
    }else if(guess < secret_number){
        printf("Too low\n");
    }else{
        return 1; // คืนค่า 1 ถ้าทายถูก
    }
    }
} 
void processPayment(int total_price , char paymentMethod[] , float *totalwithfee){
    printf ("\npaymentMethod: %s\n",paymentMethod); 
    if ((paymentMethod[0] == 'C' || paymentMethod[0] == 'c') && paymentMethod[1] == '\0'){ // \0 คือ จุดจบ
        //ถ้าผู้ใช้เลือกใช้เงินสด
        printf("Total price %d bath\n",&total_price);
        *totalwithfee = total_price;
    }else if((paymentMethod[0] == 'B' || paymentMethod[0] == 'b') && paymentMethod[1] == '\0'){
        //ถ้าใช้บัตรเครดิต
        float fee = total_price*0.05; //ค่าธรรมเนียม
        *totalwithfee = total_price + fee;
        printf("Credit card fee 5%% : %.2f baht\n",fee);
        printf("Total with fee : %2.f",*totalwithfee);
    }else{
        printf("Wrong payment method ! Select agian\n");
        *totalwithfee = total_price; //ตั้วค่าเริ่มต้นกันพลาด
    }
 
}
char calculateChange(int totalwithfee,double paid_amout , double *result1){
 
    if(paid_amout > totalwithfee){
        *result1 = (paid_amout - totalwithfee);
        return 'C'; //มีเงินทอน
    }else if(paid_amout < totalwithfee){
        *result1 = (totalwithfee - paid_amout);
        return 'S';//เงินไม่พอ    
    }else{
        *result1 = 0;//ไม่มีเงินทอนหรือเงินขาด
        return 'E'; //เงินพอดี
    }
}
 
int main (){
    store_Info (); // call function 1
 
    int year = promotionyear (); 
    printf("Enter promotion year is %d\n",year); 
 
    char exit ;            
    float price1[100];
    int a =0 ;
    float total =0 ;
 
    do{ 
    printf("Enter price ");
    scanf("%f",&price1[a]); 
    total=total+price1[a];  
 
    printf("\n"); 
    printf ("Exit for y/Y,Want to exit(y/n)  "); 
    scanf(" %c",&exit);  
 
    }while ((exit !='y')&&(exit != 'Y'));
    printf("total is %.2f\n",total); 
 
    float price_after_discount=discount1(total);
    printf("price after discount is %.2f\n",price_after_discount); 
 
    float total_price; 
    if (price_after_discount <2000){
        printf("No discount\n");
        total_price = price_after_discount*1.0;
    }else if((price_after_discount >=2000) && (price_after_discount <=5000)){
        printf("have more discount 5%%\n");
        total_price = price_after_discount*0.95;
    }else if((price_after_discount >=5001) && (price_after_discount <=10000)){
        printf("have more discount 10%%\n");
        total_price = price_after_discount*0.90;
    }else{
        printf("have more discount 20%%\n");
        total_price = price_after_discount*0.80;
    }
     printf("total price is %.2f\n",total_price);
 
    printf("===Lucky Number===\n");
    // เรียกใช้ฟังก์ชันทายเลข
    if(guess_number()){
        printf("congratulations\n");
    }
 
    char paymentMethod[10]; //ใช้เหมือน char name[10]
    // รับข้อมูล
    printf("Please Select payment (C for Cash, B for Credit card): ");
    scanf(" %s",paymentMethod);
    //เรียกฟังก์ชัน processPayment()
    float totalwithfee;
    processPayment(total_price,paymentMethod, &totalwithfee);
 
 
    double paid_amout, result1;
    char status;
    //รับข้อมูล
    printf("\nEnter paid money: ");
    scanf("%lf",&paid_amout);
    //เรียกฟังก์ชันคำนวณเงินทอน
    status = calculateChange(totalwithfee , paid_amout, &result1);
    //แสดงผลตามที่คืนค่า
    if(status == 'C'){
        printf("Give change: %.2f\n",result1);
    }else if(status == 'S'){
        printf("Money Not enough: %.2f\n",result1);
    }else{
        printf("Exactly final total\n");
    }
 
    return 0 ;
 
 
}

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