Question

#include <stdio.h>

int main()
{
        char n='Y';
        fflush(stdin);
        while(n=='Y')
        {
                printf("Add Next Y/N: ");
                n=getc(stdin);
        }
        printf("n = %c",n);
}

This loop ends after 1st iteration without taking input from keyboard.

Answer 1

On my system, getc() does not seem to return until I hit the return key. Which means that ‘Y’ is always followed by ‘\n’. So in order to keep looping I had to add a condition to the while:

#include <stdio.h>
#include <ctype.h>
int main()
{
   char n = 'Y';
   while ( toupper(n) == 'Y' || n == '\n'  )
   {
      if ( n != '\n' )
      {
         printf("Add Next Y/N: ");
      }
      n = getc(stdin);
   }
}

fgets() seems to work better:

#include <stdio.h>
#include <ctype.h>
int main()
{
   char input[100] = { "Y" };
   while ( toupper(input[0]) == 'Y' )
   {
      printf("Add Next Y/N: ");
      fgets(input,sizeof(input),stdin);
   }
}

Edit for comment below:
scanf() also has issues with carriage return. Better to fgets() and then sscanf(). Since you are doing the extra getchar() I think you can get rid of the check for ‘\n’. Try this:

#include <stdio.h>
#include <ctype.h>

struct item {
      char name[100];
      int avg;
      double cost;
};


int main()
{

   FILE *fp = fopen("getc.txt","w");
   struct item e;
   char line[200];
   char next = 'Y';
   while(toupper(next) == 'Y') 
   { 
      printf("Model name, Average, Price: "); 
      fgets(line,sizeof(line),stdin);
      sscanf(line,"%s %d %f",e.name,&e.avg,&e.cost); 
      fwrite(&e,sizeof(e),1,fp); 
      printf("Add Next (Y/N): "); 
      next = getc(stdin);
      getchar(); // to get rid of the carriage return
   }
   fclose(fp);
}

An alternative way without sscanf():

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

struct item {
      char name[100];
      int avg;
      double cost;
};
int main() 
{
   struct item e;
   char line[200];
   char next = 'Y';
   while(toupper(next) == 'Y') 
   { 
      printf("Model name ");
      fgets(line,sizeof(line),stdin);
      line[ strlen(line) - 1 ] = '\0'; // get rid of '\n'
      strcpy(e.name,line);
      printf("\nAverage "); 
      fgets(line,sizeof(line),stdin);
      e.avg = atoi(line);
      printf("\nPrice "); 
      fgets(line,sizeof(line),stdin);
      e.cost = atof(line);
      printf("you input %s %d %f\n",e.name,e.avg,e.cost);
      printf("Add Next (Y/N): "); 
      next = getc(stdin);
      getchar(); // get rid of carriage return
   }
}