Functions broke my app. need advice

[smogsy]

i'm trying to reduce my code by using functions (learning them atm) now ive created my functions but there coming up with errors (not on build process) but on the switch case. when i press a menu option say 1 it says ive not initialized Questions but not sure how?

if i put questions = 0; i get bad input. need advice

please be down to earth as possible as i'm new to this.

// loop.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <stdlib.h>

//Functions 
int FirstNumber (int number1, int number2);		//Random number generator


int Questions1 (void) 
{
	int Q=0;
	printf("How many questions would you like to answer?: ");
	scanf("%d", &Q);									//Saves User input to Questions Int.
	printf("you selected: %d Questions to answer\n\n", Q); //Tells you how many you selected
	return Q;
}

int Menu (void)
{
	int input=0;
	printf("===========================================\n");
	printf("AppGecko Random Maths V0.30\n");
	printf("===========================================\n");
	printf("1. Addition\n");
	printf("2. Subtraction - Not Complete\n");
	printf("3. Division - Not Complete\n");
	printf("4. Multiplication - Not Complete\n");
	scanf( "%d", &input);
	return input;
	}

int _tmain(int argc, _TCHAR* argv[])
{	
	//Variables
	int number1;
	int number2;
	int Questions;
	int USER;
	int QN;
	int CorrectAnswers = 0;
	int CPU = 0;
	int input = 0;
	//Variable End

	//Menu System
	Menu();
	//Menu System Ends//


switch ( input ) {
	case 1: // Addition 
	Questions = Questions1();

	//Loop For amount of questions selected
	for (QN = 0; QN < Questions; QN++ ) {
	number2 = rand();		//Random number generator
	number1 = rand();		//Random Number Generator
	CPU = (number1 + number2);	//Calculate Answer
	
	//Asks the Question & Gets Answer
	printf("what is %d plus %d\n",number1,number2);
	printf("Enter Your Answer: ");
	scanf_s("%d", &USER);
  
	// Checks if Answer is correct & Responds accordingly 
	if (USER == CPU) {
	printf("\nYou are Right\n\n");
	CorrectAnswers = CorrectAnswers +1;
	}
	else {
	printf("\nYou are Wrong\n\n");
	}
	number2 = 0;
	number1 = 0;
	CPU = 0;
	
	printf("Next Question\n\n");

	} 
	printf("You have Answered %d out of %d Correct\n",CorrectAnswers, Questions);
	printf("Press Any Key to End");
	

	getchar();
	break;


	case 2:
	printf("How many questions would you like to answer?: ");
	scanf("%d", &Questions);									//Saves User input to Questions Int.
	printf("you selected: %d Questions to answer\n\n", Questions); //Tells you how many you selected

	//Loop For amount of questions selected
	for (QN = 0; QN < Questions; QN++ ) {
	number2 = rand();		//Random number generator
	number1 = rand();		//Random Number Generator

	
	//Asks the Question & Gets Answer
	printf("what is %d minus %d\n",number1,number2);
	printf("Enter Your Answer: ");
	scanf_s("%d", &USER);
  
	// Checks if Answer is correct & Responds accordingly 
	if (USER == CPU) {
	printf("\nYou are Right\n\n");
	CorrectAnswers = CorrectAnswers +1;
	}
	else {
	printf("\nYou are Wrong\n\n");
	}
	number2 = 0;
	number1 = 0;
	CPU = 0;
	
	printf("Next Question\n\n");

	} 

	break;

	default:
	printf( "Bad input, Please Select Again" );
    break;
}

	printf("You have Answered %d out of %d Correct\n",CorrectAnswers, Questions);

	return 0;
}

[nonoob]

You forgot to do something with the return value of Menu() - like assign it to 'input'. Otherwise 'input' never changes.

input = Menu();

[smogsy]

thank you so much

i love you right now what a idiot i am