Recursion example

inceptionish.c

/** @file inceptionish.c
 @author Prof. Adams
 @assistance Plot overview from Wikipedia [http://en.wikipedia.org/wiki/Inception]
 @assistance Plot overview from Jamie LaFountain
 @status funky
 */
#include <stdio.h>
#include <stdbool.h>

/** Letter user enters for 'Dream' command in main menu */
const char CMD_DREAM = 'D';
/** Letter user enters for 'Look' command in main menu */
const char CMD_LOOK = 'L';
/** Letter user enters for 'Wake' command in main menu */
const char CMD_WAKE = 'W';
/** Unrealistic value to enable detection of unitialized day/month */
const int UNINITIALIZED = -42;

/** Add given number of tabs to beginning of a fresh line, plus a > marker
@param numspaces How many tabs to add
@returns nothing
@sideeffect Prints a newline, numspaces many tabs, and a > sign
*/
void indent(int numspaces);


/** Badger user until they enter a proper command 
@returns The user's correct choice
@sideeffect Prompts user for a choice, and after a user has finally made a correct choice it thanks them for each time they made an incorrect one.
*/
char getChoice();


/** Make a new 'reality' buried inside the calling environment
@param depth How many tabs to put on the output for this level
@returns nothing
@sideeffect ... it's complicated
*/
void incept(int depth);

/** Entry point for program
@returns 0 if all is well
*/
int main()
{
	printf("Welcome to the Inception-ish program!\n");
	printf("See if you can figure out how many variables are in use!\n");
	incept(0);
	printf("\nWelcome back to the 'TRUE' reality. Time to quit.\n");
}

void indent(int numspaces)
{
	int index;
	printf("\n");
	for(index=0; index<numspaces; index++) printf("\t");
	printf("> ");
}

char getChoice()
{
    char userInput;
    printf("Please select (%c)ream, (%c)ake, or (%c)ook around: ", CMD_DREAM, CMD_WAKE, CMD_LOOK);
    scanf(" %c", &userInput);
    if(userInput==CMD_DREAM) printf("reaming...");
    else if(userInput==CMD_WAKE) printf("aking...");
    else if(userInput==CMD_LOOK) printf("ooking...");
    else 
    {
        printf("'%c' wasn't one of your choices. ", userInput);
        userInput = getChoice();
        printf("Thank you. '%c' is a valid. ", userInput);
    }
    
    return userInput;
}

void incept(int depth)
{
	int year=UNINITIALIZED;
	int month=UNINITIALIZED;
	int day=UNINITIALIZED;
	char userChoice;
	
	indent(depth); printf("Welcome to Reality! Or so it seems...\n");
	
	
	while(true)
	{
        userChoice = getChoice();
        switch(userChoice)
        {
			default: 	
				indent(depth); printf("We'll just ignore that little mistake.\n"); 
				break;
                
            case CMD_LOOK: 	
				indent(depth); printf("You look at the newspaper for a date. It says...");
                if(day==UNINITIALIZED)
                {
                    printf("\n(Please enter the date, in year/month/day format like 2009/12/30): ");
                    scanf("%d/%d/%d", &year, &month, &day);
                }
                indent(depth); printf("It is the %dth day of the %dth month of year %d\n", day, month, year);
                break;
                
            case CMD_DREAM: 
                indent(depth); printf("Off to dreamland\n");
				incept(depth+1); 
                indent(depth); printf("Welcome back from your dream.\n"); 
				break;
                
            case CMD_WAKE: 	
				indent(depth); printf("AWAKEN!"); 
				return; 
        }
	}
	indent(depth); printf("ERROR: You escaped a WHILE(TRUE) loop!?!?!?");
}