Memory fault(coredump) error

Gigantor · 10-30-2005, 09:29 PM

Hello, I'm fairly new to C. I am attempting to write a program to act as a "Math menu." 1st the user would enter A, S, M, D or E. For Add, Subtract, Multiply, Divide or to Exit the program. If the user selects, A, S, M, or D. Then the program would prompt the user for 2 numbers and do the mathmatical equation. I think I have most of it written, I'm just getting a "Memory fault(coredump)" error. I'm not exactly sure what is happening. Although, I just realized the char error. But other than that is there anything else I should be looking out for?Someone please help me out. My code is below...

Code:

#include<stdio.h>
int main()
{
    int num1, num2;
    float A, S, M, D, E, total;
    char choice;

    printf("Please enter a letter to perform a mathmatical calculation.\n");
    printf("A, S, M, D, or E for Add, Subtract, Multiply, Divide or Exit.\n");
    fflush(stdin);
    scanf("%C", &choice);
       if (choice == 'E')
	 {
	   printf("Goodbye thank you for using The Calculator.\n");
	   return 0;
	 }
       else if (choice == 'A', 'S', 'M', 'D')
	 {
	   printf("Please enter the first number to perform your equation.\n");
	   scanf("%f", num1);
	   fflush(0);
	   printf("Please enter the second number of your equation.\n");
	   scanf("%f", num2);
	   fflush(0);
	 }
          if (choice == 'A')
	      {
		total = num1 + num2;
		printf("%d plus %d equals %d\n", num1, num2, total);
	      }
	  else if (choice == 'S')
	      {
		total = num1 - num2;
		printf("%d minus %d equals %d\n", num1, num2, total);
	      }
	  else if (choice == 'M')
	      {
		total = num1 * num2;
		printf("%d multiplied by %d equals %d\n", num1, num2, total);
	      }
          else if (choice == 'D')
	      {
		total = num1 / num2;
		printf("%d divided by %d equals %d\n", num1, num2, total);
	      }
       return 0;
 }

Wim Sturkenboom · 10-30-2005, 10:59 PM

scanf needs a pointer to the variable

Code:

scanf("%f", &num1);

You did this right for the choice, but not for the ints.
Further you're telling scanf to read a float, but num1 is an integer.
You're also telling printf to print an integer, but you're passing a float (total); might work and might not work.

BTW It's usefull to indicate more or less where the problem occurs.

Question: any reason to have floats A, S, M, D and E? They're not used anywhere.

naf · 10-30-2005, 11:05 PM

Comments inserted below:

Code:

#include<stdio.h>
int main()
{
    int num1, num2;
    float A, S, M, D, E;
    int total; /* You are adding two integers?  The result fits fine in a total otherwise you may lose significant digits. */
    char choice;

    printf("Please enter a letter to perform a mathmatical calculation.\n");
    printf("A, S, M, D, or E for Add, Subtract, Multiply, Divide or Exit.\n");
    fflush(stdin);
    scanf("%c", &choice);
       if (choice == 'E')
	 {
	   printf("Goodbye thank you for using The Calculator.\n");
	   return 0;
	 }
       else if( ( choice == 'A' ) || 
                ( choice == 'S' ) ||
                ( choice == 'M' ) ||
                ( choice == 'D' ) ) /* You cannot compare to a list, it has to be itemized out if you use an expression. */
	 {
	   printf("Please enter the first number to perform your equation.\n");
	   scanf("%d", &num1);/* You need to match types (%d for int, or %f for float).  Moreover, scanf needs addresses, so the ampersand is a requirement. */
	   fflush(0);
	   printf("Please enter the second number of your equation.\n");
	   scanf("%d", &num2);/*See previous comment. */
	   fflush(0);
	 }
          if (choice == 'A')
	      {
		total = num1 + num2;
		printf("%d plus %d equals %d\n", num1, num2, total);
	      }
	  else if (choice == 'S')
	      {
		total = num1 - num2;
		printf("%d minus %d equals %d\n", num1, num2, total);
	      }
	  else if (choice == 'M')
	      {
		total = num1 * num2;
		printf("%d multiplied by %d equals %d\n", num1, num2, total);
	      }
          else if (choice == 'D')
	      {
		total = num1 / num2;
		printf("%d divided by %d equals %d\n", num1, num2, total);
	      }
       return 0;
 }

Alternatively, you can use switch instead of if:

Code:

#include<stdio.h>
int main()
{
    int num1, num2;
    float A, S, M, D, E;
    int total;
    char choice;

    printf("Please enter a letter to perform a mathmatical calculation.\n");
    printf("A, S, M, D, or E for Add, Subtract, Multiply, Divide or Exit.\n");
    fflush(stdin);
    scanf("%c", &choice);
    
    switch( choice )
    {
    case 'E':
    default:
        printf("Goodbye thank you for using The Calculator.\n");
        break;
    case 'A':
    case 'S':
    case 'M':
    case 'D':        
        printf("Please enter the first number to perform your equation.\n");
        scanf("%d", &num1);
        fflush(0);
        printf("Please enter the second number of your equation.\n");
        scanf("%d", &num2);
        fflush(0);

        switch( choice )
        {
        case 'A':
            total = num1 + num2;
            printf("%d plus %d equals %d\n", num1, num2, total);
            break;
        case 'S':
            total = num1 - num2;
            printf("%d minus %d equals %d\n", num1, num2, total);
            break;
        case 'M':
            total = num1 * num2;
            printf("%d multiplied by %d equals %d\n", num1, num2, total);
            break;
        case 'D':
            total = num1 / num2;
            printf("%d divided by %d equals %d\n", num1, num2, total);
            break;
        }
    }
    
    return 0;
}

Or

Code:

#include<stdio.h>
int main()
{
    int num1, num2;
    float A, S, M, D, E;
    int total;
    char choice;
    const char *operation;

    do 
    {
        printf( "Please enter a letter to perform a mathmatical calculation.\n"
                "A, S, M, D, or E for Add, Subtract, Multiply, Divide or Exit.\n" );
        fflush( stdin );
        scanf( "%c", &choice );
        
        switch( choice )
        {
        case 'E':
        default:
            printf( "Goodbye thank you for using The Calculator.\n" );
            break;
        case 'A':
        case 'S':
        case 'M':
        case 'D':        
            printf( "Please enter the first number to perform your equation.\n" );
            scanf( "%d", &num1 );
            fflush( 0 );
            printf( "Please enter the second number of your equation.\n" );
            scanf( "%d", &num2 );
            fflush( 0 );
            
            switch( choice )
            {
            case 'A': total = num1 + num2, operation = "plus"; break;
            case 'S': total = num1 - num2, operation = "minus"; break;
            case 'M': total = num1 * num2, operation = "multiplied"; break;
            case 'D': total = num1 / num2, operation = "divided"; break;
            }
            printf("%d %s %d equals %d\n", num1, operation, num2, total);
        }
    } while( choice != 'E' );
    
    return 0;
}

You still have a danger that your numbers may produce invalid results. Like adding two very big numbers or dividing by zero. Good luck.

Gigantor · 10-30-2005, 11:19 PM

Well the A, S, M, D, and E floats are supposed to be 'char' and not float. i changed that. but the problem persists after it asks for the first number. Then it displays the "Memory fault(coredump)" error. I thought it was a problem with 'fflush(stdin)' command, but i guess not.

I've replaced a lot in the code tonight and I'm going to display the new code in a little while. Thank you for your help.

Gigantor · 10-30-2005, 11:20 PM

oh thanks naf! I will try that!

bigearsbilly · 10-31-2005, 03:11 AM

fflush stdin doesn't do anything.