Thread: Currency Convertor

Hi,

Thanks for all the help so far. Any more sugestions would be greatly appreciated.

Thanking you.

Code:

#include <stdio.h>

/*	  Define Constants for Currency Conversion Rates	*/

#define POUND 0.70
#define KRONE 7.43
#define YEN 127

int main()
{

   /* Declare all varabials	*/

	int menu_choice, error;
	float local_amount, remote_amount;
	float USD;

	do
	{

		/*		Display Menu System		*/
		/*		5 Options		*/

		printf("1. Britain\n");
   	printf("2. Denmark\n");
   	printf("3. Japan\n");
   	printf("4. USA\n");
   	printf("5. Exit Program\n\n");

   	/* Ask user for there choice														  */
   	/* Asign the choice to varabial menu_choice, which is of int data type */
		/* Keep Asking The User for input until they enter correct data		  */



      /*		This do loop will itterate until the user enteres the desired menu option to exit	*/


		do
		{
   		printf("Please Enter Your Country Selection From The Menu: \t");
   		error = scanf("%d",&menu_choice);
      	fflush(stdin);
		}	while ( error == 0 || menu_choice < 1 || menu_choice > 5 );



   	if (menu_choice == 1)
      {

         /* Ask user for there choice */
   		/* Asign the choice to varabial menu_choice, which is of int data type */
      	/* Keep Asking The User for input until they enter correct data		  */

			printf("\n\nDo you wish to convert from:\n\n");
			printf("1. Euro to Pound(Sterling)\n");
         printf("2. Pound(Sterling) to Euro\n\n");

         do
         {
         	printf("Please Enter Your Choice From The Menu: \t");
         	error = scanf("%d",&menu_choice);
            fflush(stdin);
         }	while ( error == 0 || menu_choice < 1 || menu_choice > 2 );

      	if (menu_choice == 1)
         {
         	printf("\n\nEuro to Pound(Sterling):\n\n");
            printf("Please Enter Euro Amount to be Converted: \t");
            scanf("%f",&local_amount);

         	remote_amount = local_amount * POUND;

            printf("\n%.2f Euro is equal to %.2f Pound\n\n",local_amount, remote_amount);
            menu_choice = 0;
         }

         if (menu_choice == 2)
         {

         	printf("\n\nPound(Sterling) to Euro:\n\n");

         	printf("Please Enter Pound(Sterling) Amount to be Converted: \t");
            scanf("%f",&local_amount);

            remote_amount = local_amount / POUND;

            printf("\n%.2f Pound is equal to %.2f Euro\n\n",local_amount, remote_amount);

            menu_choice = 0;
         }
      }

      if (menu_choice == 2)
      {
      	printf("\n\nDo you wish to convert from:\n\n");
         printf("1. Euro to Krone\n");
         printf("2. Krone to Euro\n\n");

         do
         {
         	printf("Please Enter Your Choice From The Menu: \t");
            error = scanf("%d",&menu_choice);
            fflush(stdin);
         }	while ( error == 0 || menu_choice < 1 || menu_choice > 2 );

         if (menu_choice == 1)
         {
         	printf("\n\nEuro to Krone:\n\n");
            printf("Please Enter Euro Amount to be Converted: \t");
            scanf("%f",&local_amount);

            remote_amount = local_amount * KRONE;

            printf("\n%.2f Euro is equal to %.2f Krone\n\n",local_amount, remote_amount);

            menu_choice = 0;

         }

         if (menu_choice == 2)
      	{

      		printf("\n\nKrone to Euro:\n\n");

            printf("Please Enter Krone Amount to be Converted: \t");
            scanf("%f",&local_amount);

            remote_amount = local_amount / KRONE;

         	printf("\n%.2f Krone is equal to %.2f Euro\n\n",local_amount, remote_amount);

            menu_choice = 0;

         }
      }

   	if (menu_choice == 3)
      {
      	printf("\n\nDo you wish to convert from:\n\n");
         printf("1. Euro to Yen\n");
         printf("2. Yen to Euro\n\n");

         do
         {
         	printf("Please Enter Your Choice From The Menu: \t");
            error = scanf("%d",&menu_choice);
            fflush(stdin);
         }	while ( error == 0 || menu_choice < 1 || menu_choice > 2 );

         if (menu_choice == 1)
         {
         	printf("\n\nEuro to Yen:\n\n");

            printf("Please Enter Euro Amount to be Converted: \t");
            scanf("%f",&local_amount);

            remote_amount = local_amount * YEN;

            printf("\n%.2f Euro is equal to %.2f Yen\n\n",local_amount, remote_amount);

            menu_choice = 0;

         }

         if (menu_choice == 2)
         {

         	printf("\n\nYen to Euro:\n\n");

            printf("Please Enter Yen Amount to be Converted: \t");
            scanf("%f",&local_amount);

            remote_amount = local_amount / YEN;

            printf("\n%.2f Yen is equal to %.2f Euro\n\n",local_amount, remote_amount);

            menu_choice = 0;

         }
      }

   	if (menu_choice == 4)
      {
      	printf("\n\nDo you wish to convert from:\n\n");
         printf("1. Euro to US Dollars\n");
         printf("2. US Dollars to Euro\n\n");

         do
         {
         	printf("Please Enter Your Choice From The Menu: \t");
            error = scanf("%d",&menu_choice);
            fflush(stdin);
         }	while ( error == 0 || menu_choice < 1 || menu_choice > 2 );

         printf("\nExample:\t\t1 EURO = POUND 0.70\n\t\t\t1 EURO = KRONE 7.43\n\n");

         do
         {
         	printf("Please Enter Current US Dollar Exchange Rate: \t");
            error = scanf("%f",&USD);
            fflush(stdin);
         } 	while ( error == 0 || USD <= 0);

         if (menu_choice == 1)
         {
         	printf("\n\nEuro to US Dollars:\n\n");

            printf("Please Enter Euro Amount to be Converted: \t");
            scanf("%f",&local_amount);

            remote_amount = local_amount * USD;

            printf("\n%.2f (EURO) is equal to %.2f (USD)\n\n",local_amount, remote_amount);

            menu_choice = 0;

         }

         if (menu_choice == 2)
         {

         printf("\n\nUS Dollars to Euro:\n\n");

         printf("Please Enter US Dollar Amount to be Converted: \t");
         scanf("%f",&local_amount);

         remote_amount = local_amount / USD;

         printf("\n%.2f (USD) is equal to %.2f (Euro)\n\n",local_amount, remote_amount);

         menu_choice = 0;

         }
      }

   	if (menu_choice == 5)
      {
      	printf("Thank You Come Again!");
      }

	} while(menu_choice == 0);

   printf("\n\n\n\n\n\n$$$$ UP!");
   return 0;
}

>float USD;
This can be confusing. The general convention is for macros and named constants to have names in all capital letters. It's a matter of style, but a lot of people are used to this one.

>fflush(stdin);
Big no-no, flushing an input stream is undefined behavior.

>while ( error == 0 || menu_choice < 1 || menu_choice > 5 );
scanf can return EOF too. Better something more like this:

Code:

int out_of_range ( int value, int low, int high )
{
  return value < low || high > value;
}
...
while ( error != 1 || out_of_range ( menu_choice, 1, 5 ) );

>error = scanf("%d",&menu_choice);
This is the second time you use the same loop for input, consider wrapping the functionality in a function.

>scanf("%f",&local_amount);
Always, always check scanf's return value. No exceptions. If you must use it, at least use it in a relatively safe way.

You might consider using switch cases instead of unrelated if statements for running a menu option. It tends to keep things a bit cleaner. That's my quick glance suggestion list, if I missed anything you have my apologies.