#include <stdio.h>


int add ( int x, int y ); /* Add y to x */
int sub ( int x, int y); /* Subtracts y from x */
int mult ( int x, int y ); /* Multiplies x with y */
int div ( int x, int y ); /* Divides x with y */
	
int main()
{
    int input;
    int x;
    int y;
    
    printf( "CALCULATOR\n" );
    printf( "\n" );
    printf( "What do you want to do ?\n" );
    printf( "1. Add\n" );
    printf( "2. Extract\n" );
    printf( "3. Multiply\n" );
    printf( "4. Divide\n" );
    printf( "5. Exit\n" );
    printf( "Selection: " );
    scanf( "%d", &input );
    switch ( input ) {
        case 1:            /* When 1 is chosen call add function */
               printf( "Please input two numbers to be added to eachother: \n" );
               scanf( "%d", &x );
               scanf( "%d", &y );
               printf( "The result is: %d\n", add( x, y ) );            
            break;
        case 2:          /* When 2 is chosen call substract function */
               printf( "Please input two numbers to be extracted from eachother: \n" );
               scanf( "%d", &x );
               scanf( "%d", &y );
               printf( "The result is: %d\n", sub( x, y ) );
            break;
        case 3:         /* When 3 is chosen call multiply function */
               printf( "Please input two numbers to be multiplied: \n" );
               scanf( "%d", &x );
               scanf( "%d", &y );
               printf( "The result is: %d\n", mult( x, y ) );
            break;
        case 4:        /* When 4 is chosen call divide function */
               printf( "Please input two numbers to be divided: \n" );
               scanf( "%d", &x );
               scanf( "%d", &y );
               printf( "The result is: %d\n", div( x, y ) );
            break;             
        case 5:        /* When 5 is chosen stop the program */
            printf( "Shutting Down...\n" );
            break;
        default:            
            printf( "Bad input, quitting!\n" );
            break;
    }
    getchar();
    return 0;
}

int add (int x, int y)
{
  return x + y; 
}

int sub (int x, int y)
{
    return x - y;
}

int mult (int x, int y)
{
  return x * y;
}

int div (int x, int y)
{
    return x / y;
}