Question

I’m having a problem understanding how to read in a string to a structure member array. I have a structure called ‘customer’ and a member called ‘char last_name[20]’. I prompt the user to enter in his last name and that last name is to be stored in the ‘last_name[20]’ variable. The condition is that I have to use a do…while loop.

Here’s the code:

void get_customer_info(struct customer *p_customer_start, int customer_num)
{
   struct customer *p_customer;

   for (p_customer = p_customer_start; (p_customer - p_customer_start) < 
        customer_num; p_customer++)
   {
      printf("\nCustomer number %d: ", (p_customer - p_customer_start) + 1);

      while (getchar() != NEW_LINE); 

      printf("\n   Enter the customer's last name: ");

      // *THIS PART IS THE PROBLEM* 
      do
      {
         p_customer->last_name = getchar();         
         p_customer->last_name++;
      } while (*p_customer->last_name != NEW_LINE);

   }
   return;
}

Problem is, with that algorithm last_name[0] does not get checked, it moves to ‘last_name[1]’ before it gets checked for a new line. And yes, a do…while construct must be used (this is for a class).

I appreciate anyone’s thoughts.

Answer 1

Ok, the solution with NO INDEXES would be;

char *pointer;

/* other code here */
pointer = p_customer->last_name 
do {
    *pointer = getchar();
    pointer += sizeof( char );
} while ( *(pointer - sizeof( char ) )!= NEW_LINE );

if you want to be sure not to go out of array bound…….simply do not use do while =) (which I always reccomend, as you must read lots of line before understanding the loop condition (and in a multinested function this is’t a real readibility problem