Write a program that will prompt for and read a positive integer less than 1000
from the keyboard, and then create and output a string that is the value of the integer in words.

For example, if 941 is entered, the program will create the string "Nine hundred and forty one".

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

void main(void)
{
	char unit_words[][20] = {"zero", "one","two","three","four","five","six","seven","eight","nine"};
	char teen_words[][20] = {"ten", "eleven","twelve","thirteen","fourteen","fifteen","sixteen","seventeen","eighteen","nineteen"};
	char ten_words[][20] = {"error", "error","twenty","thirty","forty","fifty","sixty","seventy","eighty","ninety"};
	char hundred[] = " hundred";
	char and[] = " and ";

	char value_str[50] = "";	   /* output string */
	int value = 0;                     /* Integer to be converted        */
	int digits[] = {0,0,0};            /* Stores digits of value entered */
	int i = 0;

	do{
  		printf("Enter a positive integer less than 1000: ");
  		scanf("%d",&value);
	}while(value<1 || value >=1000);
 
	// get the digits of the number and store it in the digits array
  	while(value > 0)
  	{
    		digits[i++] = value%10;
    		value /= 10;
  	}

	// checking the hundred digit
  	if(digits[2] > 0)
  	{
   		strcat(strcat(value_str,unit_words[digits[2]]), hundred);
    		if(digits[1]>0 || digits[0]>0)
      			strcat(value_str, and);
  	}
  	if(digits[1] > 0)
  	{
    		if(digits[1] == 1)
      			strcat(value_str,teen_words[digits[0]]);
    		else
    		{
      			strcat(value_str,ten_words[digits[1]]);
      			if(digits[0] > 0)
        			strcat(strcat(value_str, " "), unit_words[digits[0]]);
    		}
  	}
  	else
    		if(digits[0] > 0)
      			strcat(value_str, unit_words[digits[0]]);
  
	printf("\n%s\n", value_str);
}