Thread: Newbie Again

I've gotten this far, but I don't know how to use the 'function' properly... I've tried several things, but keep coming back to this base code because I know it works.

Can anyone give me a better idea of how to take this part of the coding in the switch:

Code:

printf("\nPlease Enter the Amount in x.xx Hong Kong Dollars to Convert.\n$");
    scanf("%f", &f_input_AMT);  //get AMT input from User for HKD conversion
    f_result[4] = f_input_AMT * f_const_HKD;
    printf("\n$%.2f Hong Kong Dollars is equal to $", f_input_AMT);
    printf("%.2f US Dollars.\n\n", f_result[4]);

And make it a function? Problem is that I can't figure out how to pass the menu selection as an argument and get the right result. I keep getting mixed responses.

I understand that I'm going to have to do something like this:

Code:

getCurrencyValue(void)
printf("\nPlease Enter the Amount in x.xx (first argument) to convert. \n$)", (first argument);
scanf("%f", $f_input_AMT);  //get amt for conversion
f_result[4] = f_input_AMT * f_const_(need argument here to define what constant to use);
printf("\n$.2f (first argument) is equal to $", f_input_AMT);
printf("%.2f US Dollars.\n\n", f_result[4]);

I just don't quite get how to figure out how to get the argument from my menu selection and tell the program what constant to use in the calculation.

Any help, tips, pointers are appreciated.

Full Program

Code:

//Currency Conversion Program
//Written by ***********, University of Phoenix
//Version 3 4/2/2006

#include <stdio.h>
#include <system.h>
#include <stdlib.h>
#include <ctype.h>

//global variable declarations and initialization with foreign exchange rates from <http://www.xe.com/ucc.convert.cgi> as of 4/2/2006
//this global variable defnition is to remain constant throughout use in the program

#define f_const_USD 1.00;	 	//1.00 USD = 1.00 USD		*United States Dollar*		 	
#define f_const_GBP 1.73710;	 	//1.00 GBP = 1.73710 USD	*United Kingdom Pounds*
#define f_const_CAD 0.855872; 	//1.00 CAD = 0.855872 USD 	*Canadian Dollars*
#define f_const_MXN 0.0919608; 	//1.00 MXN = 0.0919608 USD 	*Mexican Pesos*
#define f_const_JPY 0.00849675;	//1.00 JPY = 0.00849675 USD 	*Japanese Yen*
#define f_const_HKD 0.128871;		//1.00 HKD = 0.128871 USD 	*Hong Kong Dollars*

main(void)  //Main Program for Currency Conversion
{
	//The following f_input variable is for storing the AMT input from the user, declared initially as '0'
	float f_input_AMT = 0.00;  
	//The following f_result array is for storing calculations within the program declared initially as '0'
	float f_result[4] = {0.00};
	// f_result[0] = United Kingdom Pounds
	// f_result[1] = Canadian Dollars
	// f_result[2] = Mexican Pesos
	// f_result[3] = Japanese Yen
	// f_result[4] = Hong Kong Dollars
	
	//variable declaration for menu input, default is '0'
	int i_menu_choice = '0';
		
	do  //Do while structure so program will continue until user selects 6 to exit
	{
		do //Error Checking Loop Structure for Menu Selection
		{
			//create menu to choose currency conversion type
			printf("\n\tCurrency Conversion\n");  //Title of Program
			printf("\n1\tConvert United Kingdom Pounds to US Dollars");
			printf("\n2\tConvert Canadian Dollars to US Dollars");
			printf("\n3\tConvert Mexican Pesos to US Dollars");
			printf("\n4\tConvert Japanese Yen to US Dollars");
			printf("\n5\tConvert Hong Kong Dollars to US Dollars");
			printf("\n6\tExit Currency Conversion Program\n\n");
			//Accept input for menu selection
			printf("Please make your selection now: ");
			i_menu_choice = getchar();
		
	
		//switch structure for menu selection
		switch (i_menu_choice)
		{
		case '1':
			printf("\nYou Selected Conversion from United Kingdom Pounds to US Dollars.");
			do  //begin do structure to error check f_input_AMT for digits
			{
				printf("\nPlease Enter the Amount in x.xx United Kingdom Pounds to Convert.\n$");
				scanf("%f", &f_input_AMT);  //get AMT input from User for GBP conversion
				f_result[0] = f_input_AMT * f_const_GBP;
				printf("\n$%.2f United Kingdom Pounds is equal to $", f_input_AMT);
				printf("%.2f US Dollars.\n\n", f_result[0]);
			}
			while (isdigit (f_input_AMT));  //end do structure to error check f_input_AMT for digits
			break;
		case '2':
			printf("\nYou Selected Conversion from Canadian Dollars to US Dollars.");
			do  //begin do structure to error check f_input_AMT for digits
			{
				printf("\nPlease Enter the Amount in x.xx Canadian Dollars to Convert.\n$");
				scanf("%f", &f_input_AMT);  //get input from User for CAD conversion
				f_result[1] = f_input_AMT * f_const_CAD;
				printf("\n$%.2f Canadian Dollars is equal to $", f_input_AMT);
				printf("%.2f US Dollars.\n\n", f_result[1]);
			}
			while (isdigit (f_input_AMT));  //end do structure to error check f_input_AMT for digits
			break;
		case '3':
			printf("\nYou Selected Conversion from Mexican Pesos to US Dollars.");
			do  //begin do structure to error check f_input_AMT for digits
			{
				printf("\nPlease Enter the Amount in x.xx Mexican Pesos to Convert.\n$");
				scanf("%f", &f_input_AMT);  //get input from User for MXN conversion
				f_result[2] = f_input_AMT * f_const_MXN;
				printf("\n$%.2f Mexican Pesos is equal to $", f_input_AMT);
				printf("%.2f US Dollars.\n\n", f_result[2]);
			}
			while (isdigit (f_input_AMT));  //end do structure to error check f_input_AMT for digits
			break;
		case '4':
			printf("\nYou Selected Conversion from Japanese Yen to US Dollars.");
			do  //begin do structure to error check f_input_AMT for digits
			{
				printf("\nPlease Enter the Amount in x.xx Japanese Yen to Convert.\n$");
				scanf("%f", &f_input_AMT);  //get AMT input from User for JPY conversion
				f_result[3] = f_input_AMT * f_const_JPY;
				printf("\n$%.2f Japanese Yen is equal to $", f_input_AMT);
				printf("%.2f US Dollars.\n\n", f_result[3]);
			}
			while (isdigit (f_input_AMT));	//end do structure to error check f_input_AMT for digits
			break;
		case '5':
			printf("\nYou Selected Conversion from Hong Kong Dollars to US Dollars.");
			do  //begin do structure to error check f_input_AMT for digits
			{
				printf("\nPlease Enter the Amount in x.xx Hong Kong Dollars to Convert.\n$");
				scanf("%f", &f_input_AMT);  //get AMT input from User for HKD conversion
				f_result[4] = f_input_AMT * f_const_HKD;
				printf("\n$%.2f Hong Kong Dollars is equal to $", f_input_AMT);
				printf("%.2f US Dollars.\n\n", f_result[4]);
			}
			while (isdigit (f_input_AMT));  //end do structure to error check f_input_AMT for digits
			break;
		case '6':
			return 0;  //end program
		default:
			printf("\nYou Have Made and Invalid Selection.  Please Try Again.\n\n\n");
			i_menu_choice = getchar();						
		} //end switch
		} //end error check do while for menu selection criteria
		while (!isdigit(i_menu_choice) || (i_menu_choice , '1') && (i_menu_choice > '6'));  
	
	} //end program run do while statement
	while (i_menu_choice != '6');

}  //end main program