/* Filename: HW3.c*/
/* This program gives a menu for finding Factorials,             *
 * Powers, Factors, Prime Numbers, Prime Factors, and Palindromes*\

/******************************************************************
 * Programmer: Matthew Glynn                                      * 
 * Date : 02/07/2007                                              *
 * Homework # 3                                                   *
 * HW3.c                                                          *
 * Algorithm: This program gives a menu for finding Factorials,   *
 * Powers, Factors, Prime Numbers, Prime Factors, and Palindromes *
 *																  *
 *	I have included the Factorial and Prime Number Problems.      *
 ******************************************************************/

/* Submitted to ICON Dropbox at 5:07 PM on 02/0702007*/

#include <stdio.h> /*the library to be used */

void printMenu(); /*User-defined function */

void printMenu() /* what is iside the function printMenu()*/

{
		printf("\n Welcome to Homework number 3!\n"); 
		printf("\n 1. * Factorial\n ");
		printf("2. Power\n "); 
		printf("3. Factors\n ");
		printf("4. * Prime Numbers\n ");
		printf("5. Prime Factors\n ");
		printf("6. Palindromes\n ");
		printf("================\n ");
		printf("0. Exit\n ");
		printf("\nEnter your choice: ");
		


}/* end printMenu() */


int main( void ) /* function main begins program execution */



{ 

	int choice = 1;            /* the selection from the menu */
	int i;					   /* used as a constant in the factorial code */
	int factorial;			   /* used as a variable in the factorial code */
	int value; 			       /* used as a variable in the factorial code */
	int loop = 1;				/* used for the while loop */
	int p, n, div;              /* used in Prime Numbers Program */


	while(loop > 0 && choice != 0) /* loops the menu and sub programs until 0 is entered as a choice */


	{
		printMenu();  /* Calling the user-defined function printMenu()*/


		scanf("%d", &choice); /* obtain menu choice from user*/


	switch (choice)                  /* select the type of calculation */

		{
		case 0: /* 0 is the choice to exit the program */


			printf("\nHave a good day!\n\n"); /* a nice way to say good bye*/


				break;


		case 1: 


		/* This is the factorial program */
		{    

		printf("\nWelcome to Factorials!!!\n");

		printf("\nCompute the factorial of an integer.\n\n Enter an integer: ");  

		scanf("%d",&value); /* Read value from user */
			factorial=1;    
			if (value >= 1 && value <= 10)/*check if value is in range of 1-10 */

		{
			/*calculation of the factorial */
	
			for (i=1; i<=value; i++)      
	
			   factorial=factorial*i;    
	
		 printf("%d! = %d\n\n",value,factorial);  
	
		}
			else
				 printf("\nPlease enter a number from 1-10 for factorials\n\n");  
		}/* end of factorial program */



				break;

		case 2: 

			printf("Power has not been created yet\n");



				break;

	    case 3: 

			
			printf("Factors has not been created yet\n");


				break;

	    case 4:

		{
		   printf("\nWelcome to Prime Numbers!!!\n");

		   printf("\n Find prime numbers less than an integer. \n");

		   printf("\nEnter an integer: "); 

		   scanf("%d", &n);/* Read value from user */

		   printf("\n\nPrime numbers less than %d: \n\n",n);


		for( p = 2; p <= n; p++) {

			/* try to find a divisor of p */

		for( p = 2; p <= n; p++) {

			/* try to find a divisor of p */

			  for(div = 2; div < p; div++) {

				 if( p % div == 0)

					   /* found a divisor */

					break;   

				   /* so p is not a prime */

			  }

			  if (div == p)

		   /* exhausted possible divisors */



				 printf("  %d\n ", p); /* display result of calculation */

						 /* so p is prime */

		   }

		   printf("\n");

		}
		}

				break; 

	    case 5:

			printf("Prime Factors has not been created yet\n");



				break; 

	    case 6:

			printf("Prime Numbers has not been created yet\n");



				break; 

		default: printf("This is not an option\n");

	 }
	}/*end while*/
 
    return 0; /* indicate program ended successfully */

} /* ends function main */

/*************************************************************************
 * Programmed by: Matt Glynn                                             *
 *************************************************************************/