How to write a “C” Program to evaluate the value of a function at non tabulated points by Newton's Divided Difference Method.

#include<stdio.h>
#include<conio.h>
#include<math.h>
void main()
{
  float x[10],y[10][10],sum,p,u,temp;
  int i,n,j,k=0,f,m;
  float fact(int);
  clrscr();
  printf("\nhow many record you will be enter: ");
  scanf("%d",&n);
  for(i=0; i<n; i++)
  {
  printf("\n\nenter the value of x%d: ",i);
  scanf("%f",&x[i]);
  printf("\n\nenter the value of f(x%d): ",i);
  scanf("%f",&y[k][i]);
  }
  printf("\n\nEnter X for finding f(x): ");
  scanf("%f",&p);
  for(i=1;i<n;i++)
  {
  for(j=0;j<n-i;j++)
  {
  y[i][j]=y[i-1][j+1]-y[i-1][j];
  }
  }
  printf("\n______________________________________________\n");
  printf("\n  x(i)\t   y(i)\t    y1(i)    y2(i)    y3(i)    y4(i)");
  printf("\n______________________________________________\n");
  for(i=0;i<n;i++)
  {
  printf("\n %.3f",x[i]);
  for(j=0;j<n-i;j++)
  {
  printf("   ");
  printf(" %.3f",y[j][i]);
  }
  printf("\n");
  }
  i=0;
  do
 {
  if(x[i]<p && p<x[i+1])
  k=1;
  else
  i++;
  }while(k != 1);
  f=i;
  u=(p-x[f])/(x[f+1]-x[f]);
  printf("\n\n u = %.3f ",u);
  n=n-i+1;
  sum=0;
  for(i=0;i<n-1;i++)
  {
  temp=1;
  for(j=0;j<i;j++)
  {
  temp = temp * (u - j);
  }
  m=fact(i);
  sum = sum + temp*(y[i][f]/m);
  }
  printf("\n\n f(%.2f) = %f ",p,sum);
  getch();
}
  float fact(int a)
{
  float fac = 1;
  if (a == 0)
  return (1);
  else
  fac = a * fact(a-1);
  return(fac);
}