Question using C

[canteyn]

Here is my problem, my code is working correctly, and the program is functioning as it should, however I want the person using the program to be able to enter 'y', 'Y', 'n', or 'N' for whether or not the buyer is a teacher, currently I have it setup to where the only way it works is with the lowercase 'y' and 'n' .... could someone please check my code below and tell me what I need to add to have this work with the uppercase letters as well. Thanks.

/*
     File:  lab3.c
     Author:  Nick Cantey
     Description:  This program calculates and prints a receipt for purchases.
     Date created:  2/22/2007
*/

#include <stdio.h>

/* Constants for program */

#define TEACHER_DISCOUNT_SMALL 0.1
#define TEACHER_DISCOUNT_BIG 0.12
#define SALES_TAX 0.05

int main ()

{  
     FILE* out;    /* sets out to point to a file */ 
     char teacher; /* sets teacher to be a variable for main */ 
     double salesTax, purchase_amount, discount, discount_total, total; /* variables for main */

     /* Prompting for total price of purchase and if buyer is a teacher */

     printf("Please enter total purchase amount: ");
     scanf("%lf", &purchase_amount);
     fflush(stdin);     
     printf("Is customer a music teacher (y/n)?: ");
     scanf("%c", &teacher);
     
     /* Opens receipt file */
 
     out = fopen("receipt.txt", "w"); 

     /* Determines price for teacher with a 12% discount */

     if (teacher == 'y' && purchase_amount >=100)
     {
              discount = purchase_amount*TEACHER_DISCOUNT_BIG;  
              discount_total = purchase_amount-discount;
              salesTax = discount_total*SALES_TAX;
              total = discount_total+salesTax;
              fprintf(out, "Total Purchase\t\t$%10.2lf\n", purchase_amount);
              fprintf(out, "Teacher Discount(12%%)\t$%10.2lf\n", discount);
              fprintf(out, "Sales Tax(5%%)\t\t$%10.2lf\n", salesTax);
              fprintf(out, "Total\t\t\t$%10.2lf\n", total);  
              fclose(out); 
     }

     /* Determines price for teacher with a 10% discount */

     else if ( teacher == 'y' && purchase_amount <100)
     {
              discount = purchase_amount*TEACHER_DISCOUNT_SMALL;
              discount_total = purchase_amount-discount;
              salesTax = discount_total*SALES_TAX;
              total = discount_total+salesTax;
              fprintf(out, "Total Purchase\t\t$%10.2lf\n", purchase_amount); 
              fprintf(out, "Teacher Discount(10%%)\t$%10.2lf\n", discount);
              fprintf(out, "Sales Tax(5%%)\t\t$%10.2lf\n", salesTax);
              fprintf(out, "Total \t\t\t$%10.2lf\n", total);
              fclose(out);
     }
    
     /* Determines price for a regular customer */

     else if ( teacher == 'n' && purchase_amount >0 )
     {
              salesTax = purchase_amount*SALES_TAX; 
              total = purchase_amount+salesTax;  
              fprintf(out, "Total Purchase\t\t$%10.2lf\n", purchase_amount);
              fprintf(out, "Sales Tax(5%%)\t\t$%10.2lf\n", salesTax);
              fprintf(out, "Total\t\t\t$%10.2lf\n", total);
              fclose(out);
     } 

     return; 

}

[DeMan]

I think one of the standard libraries has this, however (as I'm not really sure which one) it is a reasonably simple method to implement.....

Thsi method will change an upper case to a lower case (since that is what you test for)

char toLower(char myChar)
{
  if((myChar >= 'A') && (myChar <='Z')
  {
    return (myChar -('A' - 'a'));  
  }
  return myChar;  //character is already lowercase or not a char that has case
}

You can either do
teacher = toLower(teacher ) when you first read teacher in (probably the better idea), or you can use this at each if (if(toLower(tea cher) == 'y')) (not such a good idea, because it means alterring LOTS of code)

[Ganon11]

Either that, or every time you test for 'y', you test if it equals 'y' OR it equals 'Y'. Same with 'n'.