Homework Help C Program Loop & Switch

Hi i need help, like i dont understand this at all :/
this is the question:


A mail-order house sells five different products whose retail prices are as follows: product 1, $2.98; product 2, $4.50; product 3, $9.98; product 4, $4.49; and product 5, $6.87. Write an application that reads a series of pairs of numbers as follows:

a) Product number
b) Quantity sold for one day

Your program must use a switch structure to help determine the retail price for each product. It should calculate and display the total retail value of each product sold last week. Use a sentinel-controlled loop to determine when the program should stop looping and display the final results.

Where is your code?

Post ur code. Can't help without knowing how far u've reached.

Opps sorry i thought i did :P
The problem is that when i enter 1 is that it doesnt work and it doesnt ask for multiple inputs

Code:

---


#include <stdio.h>

int main (void)
{
  int custnum;
  int  kwh, copy;
  double totald=0.0;
  double totala=0.0;
  double totalb=0.0;
  double totalc=0.0;
  double totale=0.0;

 
  while(1) {
    printf("\nEnter Product Number or enter 0 to quit>");
    scanf("%d", &custnum);

    if (custnum == 0)
      break;

    printf("Enter Quality Sold >", custnum);
    scanf("%d", &kwh);
    copy = kwh;
    while(custnum == 1) { 
      totala += (kwh * 2.98); 
     
    }
    if(custnum == 2) { 
      totalb = (kwh * 4.50);
     
    }
    if(custnum == 3) { 
      totalc = (kwh * 9.98);
   
  }
    if(custnum == 4) { 
      totald = (kwh * 4.49);
     
    }
    if(custnum == 5) { 
      totale = (kwh * 6.87);
     
    }
   
    kwh = copy;
    printf("\nProduct 1 : $%.2f\n",
    totala);
    printf("\nProduct 2 : $%.2f\n",
    totalb);
    printf("\nProduct 3 : $%.2f\n",
    totalc);
    printf("\nProduct 4 : $%.2f\n",
    totald);
    printf("\nProduct 5 : $%.2f\n",
    totale);
   
   
   
   
   
    totala = totalb = totalc = totald = totale = 0;
  }

  (void) getchar();
  system ("pause"); 
  return 0;
 
}

---

Code:

---

    while(custnum == 1) { 
      totala += (kwh * 2.98); 
     
    }

---

If 'custnum' is ever 1, this loop will run forever.


Quzah.

ahahaha thanks it works now but if i enter multiple entries like "1" twice for the product number it stops automaticaly -.-'

Code:

---


#include <stdio.h>

int main (void)
{
  int custnum;
  int  kwh, copy;
  double totald=0.0;
  double totala=0.0;
  double totalb=0.0;
  double totalc=0.0;
  double totale=0.0;
 
 
  while(1) {
    printf("\nEnter Product Number or enter 0 to quit>");
    scanf("%d", &custnum);

    if (custnum == 0)
      break;

    printf("Enter Quality Sold >", custnum);
    scanf("%d", &kwh);
    copy = kwh;
   
    if(custnum == 1) { 
      totala += (kwh * 2.98);
   
    printf("\nEnter Product Number or enter 0 to quit>");
    scanf("%d", &custnum);

    if (custnum == 0)
      break;

    printf("Enter Quality Sold >", custnum);
    scanf("%d", &kwh);
    copy = kwh;
     
    }
    if(custnum == 2) { 
      totalb = (kwh * 4.50);
     
    printf("\nEnter Product Number or enter 0 to quit>");
    scanf("%d", &custnum);

    if (custnum == 0)
      break;

    printf("Enter Quality Sold >", custnum);
    scanf("%d", &kwh);
    copy = kwh;
     
    }
    if(custnum == 3) { 
      totalc = (kwh * 9.98);
     
    printf("\nEnter Product Number or enter 0 to quit>");
    scanf("%d", &custnum);

    if (custnum == 0)
      break;

    printf("Enter Quality Sold >", custnum);
    scanf("%d", &kwh);
    copy = kwh;
   
  }
    if(custnum == 4) { 
      totald = (kwh * 4.49);
     
    printf("\nEnter Product Number or enter 0 to quit>");
    scanf("%d", &custnum);

    if (custnum == 0)
      break;

    printf("Enter Quality Sold >", custnum);
    scanf("%d", &kwh);
    copy = kwh;
     
    }
    if(custnum == 5) { 
      totale = (kwh * 6.87);
     
    printf("\nEnter Product Number or enter 0 to quit>");
    scanf("%d", &custnum);

    if (custnum == 0)
      break;

    printf("Enter Quality Sold >", custnum);
    scanf("%d", &kwh);
    copy = kwh;
     
    }
   
    kwh = copy;
    printf("\nProduct 1 : $%.2f\n",
    totala);
    printf("\nProduct 2 : $%.2f\n",
    totalb);
    printf("\nProduct 3 : $%.2f\n",
    totalc);
    printf("\nProduct 4 : $%.2f\n",
    totald);
    printf("\nProduct 5 : $%.2f\n",
    totale);
   
   
   
   
   
    totala = totalb = totalc = totald = totale = 0;
  }

  (void) getchar();
  system ("pause"); 
  return 0;
 
}

---

You seem to be repeating a lot of the same lines over and over. Most of the time you are doing that, you can instead use a loop. Consider:

Code:

---

for( x = 0; x < 5; x++ )
{
    if( scanf( "%d", &num ) == 1 )
    {
        if( num != 0 )
        {
            do stuff with the number
        }
        else break;
    }
    else break;
}

---

This might also be a good time to learn about arrays.


Quzah.

yaaaaa we havent learned that yet :'/