In checkout function g_tot calculation brings garbage value - c

Question

In this code at checkout function g_tot calculation brings garbage value. I think its because I'm calculating two variables from another two functions, but I don't know how to fix it. There's another error in restaurant function in if condition if I enter value more than 8 it'll bring garbage value to tot. But the most important one is
#include<stdio.h>
#include<conio.h>
// Global variables
int room,answr,days=0;
char name[20],choose;
int i=0,tot=0,p_tot=0,g_tot=0,z=0;
int p_price[2][5]={4000,10000,20000};
void screenheader()
{
printf("\n ::::::::::::::::::::::::::::::::::::::");
printf("\n :: ::");
printf("\n :: ############################ ::");
printf("\n :: # # ::");
printf("\n :: # WELCOME # ::");
printf("\n :: # TO # ::");
printf("\n :: # SURF HOTEL # ::");
printf("\n :: # # ::");
printf("\n :: ############################ ::");
printf("\n :: ::");
printf("\n ::::::::::::::::::::::::::::::::::::::");
}
void check_in()
{
int contact_No[20],NIC[10];
char first_name[10],last_name[10],Country[10];
system("cls");
screenheader();
printf("\n1. Packages");
printf("\n2. Room Allocation");
printf("\n3. Back\n\n");
scanf(" %d",&answr);
switch(answr)
{
case 1:{
system("cls");
printf("\n\n\nPer 2 Persons");
printf("\n\t\tPackage Name >>>> Couple");
printf("\n\t\tRs.4000/= per day");
printf("\n\t\tBed >>>> 1");
printf("\n\t\t *Tv Available");
printf("\n\n\n\n\t\t\nPer 4 Persons\n\t\tPackage Name >>>>
Family");
printf("\n\t\tRs.10,000/= per day");
printf("\n\t\tBed >>>> 2");
printf("\n\t\t*Tv Available \n\t\t*A/C \n\t\t*WIFI");
printf("\n\n\n\nPer 8 Persons\n\t\tPackage Name >>>> Deluxe");
printf("\n\t\tRs.20,000/= per day");
printf("\n\t\tBed >>>> 3 Large ");
printf("\n\t\t *Tv Available \n\t\t*A/C \n\t\t*WIFI\n\t\t*Local
Travel Guide\n\t\t*Balcony with a view\n\t\t*Writing desk");
printf("\n\n*Press 1 to go back");
getch();
check_in();
break;
}
case 2:{
printf("What package do you want?");
scanf(" %d",&i);
p_tot=p_tot+p_price[i-1];
if(i == 1)
{
printf("You have selected Couple package");
}
else if (i == 2)
{
printf("You have selected Family Package ");
}
else if (i == 3)
{
printf("You have selected Deluxe package");
}
else
{
printf("\n\nWrong input, please refer to packages and try
again.\nPress Enter to select another package");
getch();
check_in();
}
printf("\nEnter First Name:\n");
scanf(" %s",&first_name);
printf("Last Name:\n");
scanf(" %s",&last_name);
printf("How many days do you want to stay?");
scanf(" %d",&days);
printf("Enter your Country:");
scanf(" %s",&Country);
printf("Enter your NIC No:");
scanf(" %d",&NIC);
printf("Enter your Contact No:");
scanf(" %d",&contact_No);
printf("Hello %s %s you have booked a Room for
%d",&first_name,&last_name,days);
getch();
system("cls");
int main();
}
case 3: main();
}
}
void restaurant()
{
int fc[6];
char ans;
char food[8][30]={"Bread","Noodles","Salad","Popcorn","Chocolate ice
cream","Vanilla ice cream","Cold Coffee","Milk Shake"};
int price[8]={180,120,65,55,70,70,110,200};
printf("Press Enter To Continue To The Restaurant ");
getchar();
system("cls");
printf("\n\n\n\n\n\t *********");
printf("\n\t MENU CARD");
printf("\n\t *********\n\n\n");
printf("\n Food Code\t\tprice\t\t Food Name\n");
for(i=0;i<8;i++)
{
printf("\n\t\t%d",i+1);
printf("\t\tRs. %d",price[i]);
printf("\t\t%s",food[i]);
}
printf("\n\n\n\t *PRESS 0 TO GO TO THE MAIN MENU\n\t *PRESS 1 TO ORDER FOOD
: ");
scanf(" %d",&answr);
switch(answr)
{
case 0:
{
main();
break;
}
case 1:do
{
printf("\n\nENTER THE FOOD CODE YOU WANT TO HAVE :: ");
scanf("%d", &z);
if (z < 1 || z > 8)
{
printf("Invalid food code\n");
}
tot=tot+price[z-1];
printf("total so far is Rs.%d\n",tot);
printf("DO YOU WANT MORE(Y/N) ::");
scanf(" %c", &ans);
} while(ans=='y'|| ans=='Y');
printf("\n\nYour bill is Rs.%d",tot);
printf("\nYour bill will be added to the total bill at checkout");
printf("\n\nPress Enter to go back to main menu");
getch();
system("cls");
main();
}
}
void check_out()
{
system("cls");
screenheader();
printf("\n\nAre you sure you want checkout (Y/N)");
scanf(" %c",&choose);
if(choose=='n' || choose=='N')
{
main();
}
else if(choose== 'Y' || choose=='y')
{
system("cls");
screenheader();
g_tot=p_tot+tot;
printf("Total");
printf("%d",g_tot);
}
}
int main()
{
screenheader();
printf("\n\n\nPress Enter To Continue");
getchar();
system("cls");
screenheader();
printf("\n\n\n\n\t\t ************* \n");
printf("\t\t * MAIN MENU * \n");
printf("\t\t ************* \n\n\n");
printf("\t\t\t01. Check In \n");
printf("\t\t\t02.Restaurant\n");
printf("\t\t\t03.Checkout \n");
printf("\n\t\t\t04.Exit");
scanf(" %d",&answr);
switch(answr)
{
case 1:{
check_in();
break; }
case 2:{
restaurant();
break; }
case 3: {
check_out();
}
}
return 0;
}

Answer 1

if condition if I enter value more than 8 it'll bring garbage value to tot.
This is as expected. When z > 8, code attempts to access outside price[] range. Result: undefined behavior (UB). The prior if (z < 1 || z > 8) did not steer code away from price[z - 1]. Rest of code including g_tot = p_tot + tot; is now questionable.
int price[8] = {180, 120, 65, 55, 70, 70, 110, 200};
...
if (z < 1 || z > 8) {
printf("Invalid food code\n");
}
tot = tot + price[z - 1]; // UB here
...
g_tot = p_tot + tot;
Do not access price[z - 1] unless z in the range [1...8].
Other problems exist: Best to enable all compilers warnings and seem them (12+) yourself.