Thread: Help please

Originally Posted by huslayer

Adak, Thank you so much..
I tried to do what you told me but i got syntax error!!

I’m reading about the loop function but still can't get it ! As also I’ll need to do it for each of the 5 parts in the code, for each currency that I’ll convert

Thank anyway for your help, and any clarifications will be appreciated

Code:

quit = 0;
Do {

//All your menu header and menu choices go in here

//add a choice to quit the program.

}while(quit == 0);

1. Maybe the reason it's having a syntax error is because you followed the syntax above. Maybe adak mistyped the "Do" syntax that supposed to be "do".

Maybe you could try to sample code.

Code:

    do
    {
        printf( "1. Convert 1 \n" );
        printf( "2. Convert 2 \n" );
        printf( "3. Convert 3 \n" );
        printf( "0 Quit" );
        scanf( "%d", &input );fflush( stdin );
    }while( input != 0 );

since all the processes are in your main function only then you have to house your statement using the do...while or while... looping statement.

fflush( stdin );

undefined - read FAQ

Yeah, no Do, just do.

After each call to scanf(), you will need to get rid of the newline char that scanf() leaves behind.

You can use getchar(), as in:

Code:

scanf()  //any call to scanf() function.
gar = getchar(); //this pulls off one newline char scanf leaves behind

where "gar" is any char or integer variable, which can be used for "garbage". You still have
to declare "gar" (or whatever name you use), as a variable in your list of variables.

If you fail to use getchar() after each scanf() call, you will have scanf() being skipped over because it will read the newline left behind in the keyboard buffer, and will take that newline as your input, and just keep going.

You'll swear it had "skipped" over your scanf(), but it didn't.

You don't need to put a loop around each part of the five currencies - just the main menu portion. The other parts should be in one or more separate functions, that you'll call (and return from), in main().

Code:

In pseudo code:

int main()
   Declare your variables here

Start your do loop here

  do  
   {
   Your menu header here

   Your menu body here

   Get user choice here with scanf()

   gar = getchar() here

   Switch statement for user's choice, here
      which calls all other function(s).

   Functions return here
   
   }while loop ends here

If you have a problem with it, you'll have to tell me what compiler errors you are getting - not just "I'm getting
compiler errors", ok?

Also, I need you to post the code that you're having trouble with. I won't know what changes you've made, otherwise.

It's all about the details, so show em.

Code:

//this line is a problem:
while( USD <1 || USD > 100000000000000000 );

Because your data type won't come close to handling 1 * 10^17

Every part that you have separated as a choice for conversion, should be another
function:

//###################Euros is selected#################

//What to LOOOOOP

do {

    //IF condition

    if (currency_selection == 1){

    printf("\n\t------------------------------------------------------------\n");

    printf("\n\tThanks! USD to Euros is selected (Please Enter Numbers Only)\n");

    printf("\n");

    printf("\n\tAmount of USD to convert: ");

    }

    //User Input

    scanf("%f", &USD);  fflush( stdin );

}while( USD <1 || USD > 100000000000000000 );

 
    //Result if success

    printf("\n\tThe total is: %f Euros\n", USD*EUR);

    printf("\n");

    return 0;

 

//###############British Pounds is selected###############


 if (currency_selection == 2){

    printf("\n\tThanks! USD to British Pounds is selected\n");

    printf("\n\tPlease enter the amount of USD you need to convert: ");

    scanf("%f", &USD);
 }

    //Validation of dollar amount

    if ( USD <1 || USD > 100000000000000000)

    printf("\nPlease enter a valid number");

    else

    printf("\n\tThe total is: %f British Pounds\n", USD*GBP);

    printf("\n");

        return 0;

 
//##############Canadian Dollars is selected########

    if (currency_selection == 3){

    printf("\n\tThanks! USD to Canadian Dollars is selected\n");

    printf("\n\tPlease enter the amount of USD you need to convert: ");

    scanf("%f", &USD);

    //Validation of dollar amount

    if ( USD <1 || USD > 100000000000000000)

    printf("\nPlease enter a valid number");

    else
    printf("\n\tThe total is: %f Canadian Dollars\n", USD*CAD);

    printf("\n");

    }

 

//#########Japanese Yens is selected#########

    if (currency_selection == 4){

    printf("\n\tThanks! USD to Japanese Yens is selected\n");

    printf("\n\tPlease enter the amount of USD you need to convert: ");

    scanf("%f", &USD);

    //Validation of dollar amount

    if ( USD <1 || USD > 100000000000000000)

    printf("\nPlease enter a valid number");

    else

    printf("\n\tThe total is: %f Japanese Yens\n", USD*JPY);

    printf("\n");

    }


//###Australian Dollars is selected##############
    if (currency_selection == 5){

    printf("\n\tThanks! USD to Australian Dollars is selected\n");

    printf("\n\tPlease enter the amount of USD you need to convert: ");

    scanf("%f", &USD);


    //Validation of dollar amount

    if ( USD <1 || USD > 100000000000000000)

    printf("\nPlease enter a valid number");

    else

 

    printf("\n\tThe total is: %f Australian Dollars\n", USD*AUD);

    printf("\n");

    }

//#######################End######
    return 0;

}

Then, in your main menu, you just have:

if(currency_selection == 1)
   usdollar(amount);
else if(currency_selection == 2)
   gbpound(amount);
else if(currency_selection == 3)
   japanyen(amount);

//etc.

Every different colored part of code, should be a different function. Make it happen. You'll be surprised how easy it is, and how much it helps, with just some practice and study.

If you have questions, we're right here.

When that is done, the code will automatically return to the menu when it is done.

Originally Posted by huslayer

Adak, thanks so much for your help

i'm using this line "while( USD <1 || USD > 100000000000000000 );"
just to validate the input is a number not a character
i really don't know another way to validate

but i'll try to do what you've advised me to do
Thanks again

Let's assume that you don't need to implement a function just yet for some reason. The blue codes that you can see there are the things that I just added in your program. Try to test it if it satisfies your need.

**note: I replaced the variable declaration, since I'm not at home and I'm using an old compiler-the compiler is complaining about the variable declaration.

Code:

 /*Hussein yousef - University of phoenix - 2009
CSS 561 Class
Conversion Program
*/

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

int main()
{
    //Constants Declarations
    const float USD=0;
    const float EUR=0.7747;
    const float GBP=0.7182;
    const float CAD=1.2656;
    const float JPY=89.82;
    const float AUD=1.5381;

    int currency_selection = 0;

    do
    {
	  //Decoration
	  printf("\n");
	  printf("   *************************************************************************\n");
	  printf("   *                        University Of Phoenix Online                   *\n");
	  printf("   *                                                                       *\n");
	  printf("   *                            Hussein Yousef                             *\n");
	  printf("   *                                                                       *\n");
	  printf("   *                          COURSE NUMBER: CSS 561                       *\n");
	  printf("   *                                                                       *\n");
	  printf("   *************************************************************************\n");
	  printf("\n");
	  printf("                               ..:CONVERSIONS:..                            \n");
	  printf("\n");

	  //Menu
	  printf("                            ..:Currency Selection:..                         \n");
	  printf("\n\t1-Convert USD to Euros\n");
	  printf("\n\t2-Convert USD to British Pounds\n");
	  printf("\n\t3-Convert USD to Canadian Dollars\n");
	  printf("\n\t4-Convert USD to Japanese Yens\n");
	  printf("\n\t5-Convert USD to Australian Dollars\n");
	  printf("\n\t6-Quit\n" );
	  printf("\n\tPlease select a choice <1-5>: ");

	  //User Input
	  scanf("%d", &currency_selection); fflush( stdin );
	  //Validation
	  if ( currency_selection  > 6 || currency_selection < 1 )
	  printf("\nPlease Enter A Valid Number between 1 & 5\n");

	  //###########################################################
	  //Euro Selected

	  if (currency_selection == 1){
	  printf("\n\tThanks! USD to Euros is selected\n");
	  printf("\n\tPlease enter the amount of USD you need to convert: ");
	  scanf("%f", &USD);  fflush( stdin );
	  //Validation of dollar amount

	  if ( USD <1 || USD > 100000000000000000)
	  printf("\nPlease enter a valid number");

	  else
	      //Output
	      printf("\n\tThe total is: %f Euros\n", USD*EUR);
	      printf("\n");
	      //return 0;

	 }

	 //###########################################################

	 if (currency_selection == 2){
	 printf("\n\tThanks! USD to British Pounds is selected\n");
	 printf("\n\tPlease enter the amount of USD you need to convert: ");
	 scanf("%f", &USD);  fflush( stdin );

	 //Validation of dollar amount
	 if ( USD <1 || USD > 100000000000000000)
	    printf("\nPlease enter a valid number");
	 else
	    printf("\n\tThe total is: %f British Pounds\n", USD*GBP);
	    printf("\n");

	//return 0;

	}
	//###########################################################
	if (currency_selection == 3){
	    printf("\n\tThanks! USD to Canadian Dollars is selected\n");
	    printf("\n\tPlease enter the amount of USD you need to convert: ");
	    scanf("%f", &USD); fflush( stdin );
	    //Validation of dollar amount
       if ( USD <1 || USD > 100000000000000000)
	  printf("\nPlease enter a valid number");
       else
	   printf("\n\tThe total is: %f Canadian Dollars\n", USD*CAD);
	   printf("\n");
       }  

       //###########################################################
       if (currency_selection == 4){
          printf("\n\tThanks! USD to Japanese Yens is selected\n");
          printf("\n\tPlease enter the amount of USD you need to convert: ");
          scanf("%f", &USD); fflush( stdin );
       //Validation of dollar amount
       if ( USD <1 || USD > 100000000000000000)
          printf("\nPlease enter a valid number");

       else
          printf("\n\tThe total is: %f Japanese Yens\n", USD*JPY);
          printf("\n");
       }

       //###########################################################

       if (currency_selection == 5){
          printf("\n\tThanks! USD to Australian Dollars is selected\n");
          printf("\n\tPlease enter the amount of USD you need to convert: ");
          scanf("%f", &USD); fflush( stdin );
          //Validation of dollar amount
      if ( USD <1 || USD > 100000000000000000)
          printf("\nPlease enter a valid number");
      else
          printf("\n\tThe total is: %f Australian Dollars\n", USD*AUD);
          printf("\n");
      }

      //###########################################################
   }while( currency_selection != 6 ); //program will not quit until 6 is pressed
   
   return 0;
}

Eh, $l4xklynx, fflush(stdin) results in undefined behaviour.

Originally Posted by $l4xklynx

If the looping problem fixed huslayer's problem then we'll go ahead and advice him not to use scanf to avoid using fflush.

scanf is standard, fflush(stdin) - not

using one function does not require using the other