userinputproofing.c

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


int GetUserAnswer(int *userAnswer);
void PrintMenu();
void FlushStdin();
int DetermineGameMode(int *mode);
int GetAdditionCard();
int GetMutliplicationCard();

int main() {

	int returnCode = 0;
	int rounds;
	int gameMode;
	int correctAnswer;
	int userAnswer;
	int score = 0;
	srand(time(NULL));

	/*int numCorrect = 0;*/
	
	printf("Welcome to the Flash Card Game\n");
	do {
		PrintMenu();
		returnCode = DetermineGameMode(&gameMode);
		if(returnCode == 1) {
			printf("Incorrect Input. Try again.\n");
		}
	}
	while(returnCode == 1);

	if(gameMode == 3) {
		printf("Thanks for playing. Goodbye.\n");
		return(0);
	}
	else {
		returnCode = 0;
		for(rounds = 0; rounds < 6; rounds++) {
			printf("Your current score is %d out of %d\n", score, rounds);
			if(gameMode == 2) {
				correctAnswer = GetAdditionCard();
				
				do {
					if(returnCode == -1) {
						printf("Incorrect Input. Try again.\n");
					}
					returnCode = GetUserAnswer(&userAnswer);
				}
				while(returnCode == -1);

				if(userAnswer == correctAnswer) {
					score++;
					printf("Correct!\n");
				}
				else {
					printf("Incorrect\n");
				}

			}
			if(gameMode == 1) {
				correctAnswer = GetMutliplicationCard();

				do {
					if(returnCode == -1) {
						printf("Incorrect Input. Try again. \n");
					}
					returnCode = GetUserAnswer(&userAnswer);
				}
				while(returnCode == -1);

				if(userAnswer == correctAnswer) {
					score++;
					printf("Correct!\n");
				}
				else {
					printf("Incorrect\n");
				}
			}
		}
	}

	return(0);
}
void PrintMenu() {
	printf("Please select an option from the following menu: \n");
	printf("(m)ultiplication\n");
	printf("(a)ddition\n");
	printf("(q)uit\n");

}

int GetUserAnswer(int *userAnswer) {
	char inputString[4];
	char *endPointer;

	fgets(inputString, sizeof(inputString), stdin);

 	*userAnswer = strtol(inputString, &endPointer, 10);

 	if(strlen(inputString)>3) {
 		FlushStdin();
	}

	if(*inputString != '\0' && *endPointer == '\0') {
 		return 1;
 	} 	
 	return 0;
}

int DetermineGameMode(int *mode) {
	char inputString;
	int error = 0;

	inputString = getchar();

	if(inputString == 'm') {
		*mode = 1;
	}
	else if(inputString == 'a') {
		*mode = 2;
	}
	else if(inputString == 'q') {
		*mode = 3;
	}
	else {
		error = 1;
		*mode = 0;
	}
	FlushStdin();
	return error;
	
}

int GetAdditionCard() {
	int numberOne, numberTwo, sum;

	numberOne = rand() % 9;
	numberTwo = rand() % 9;
	sum = numberOne + numberTwo;

	printf("What is %d + %d?\n", numberOne, numberTwo);

	return(sum);
}
int GetMutliplicationCard() {
	int numberOne, numberTwo, product;

	numberOne = rand() % 9;
	numberTwo = rand() % 9;
	product = numberOne * numberTwo;

	printf("What is %d X %d?\n", numberOne, numberTwo);

	return(product);
}

void FlushStdin() /* function to clear the input buffer from "standard in" */
{
	char nextChar = 'a'; /* set the nextchar equal to anything at the beginning */
	nextChar = getchar();
	/* loop through the standard in buffer and "get" each character to remove 
	them from the buffer */
	while (nextChar != '\n')
	{
		nextChar = getchar();
    }
}