Having trouble with C program output

Question

As far as I know regardless of any other issues the program below should print out the title and menu options, and then prompt for user input.

However, it does absolutely nothing and when I stop the execution it prints out the menu etc and then, as it hasn't asked for the user inputted option it repeatedly prints the "This is not a valid option" line.

*EDIT: I have completely removed the loops. All I have in the program is print the title, print the menu, ask for user input, and I still get nothing to the console until after I terminate. Is there something wrong with my asking for input?

EDIT2 : It's definitely the scanf as without it everything works. I ran the code with an added function to print out the value stored in option and it told me -1 when I hadn't previously set it to 0 before asking the user to input. The program seems to be automatically assigning option instead of bothering to ask the user what they want.

#include <stdio.h>
#include <time.h>
#include <stdlib.h>

int main ()
{
    /*Print Title*/
    printf("Maths Quiz Game \n"); 
    printf("\n");

    int i;
    int rightCount = 0; //count of right answers
    int wrongCount = 0; //count of wrong answers
    int questions = 0; //user input for number of questions
    int exit = 0; //store exit option
    int option = 0; //menu option

    while(exit == 0) //while loop that keeps program running until exit is chosen
    {
        /*Menu Options*/
        printf("Please choose an option from the menu below. Enter the number of your choice. \n");
        printf(" 1. Choose number of questions for this round. (Max = 5) \n");
        printf(" 2. Start Quiz \n");
        printf(" 3. Display total of right and wrong answers. (Only availanle after quiz) \n");
        printf(" 4. Exit Game \n");

        scanf("%d", &option); //taking user menu option

        /*Error check for any input that is not a valid option. It continues until valid entry*/
        while((option != 1) || (option != 2) || (option != 3) || (option != 4))
        {
            printf("\n That is not a valid option. Please try again. \n");
            scanf("%d", &option);
        }

Answer 1

while((option != 1) || (option != 2) || (option != 3) || (option != 4))

what ever option value you enters assume 1, 1st condition of while() will be false but remaining are true so enters into loop and prints "That is not a valid option. Please try again." so replace || with logical And(&&) .

while((option != 1) && (option != 2) && (option != 3) && (option != 4))

now here if you entered correct input it will not display "That is not a valid option. Please try again"

Answer 2

How about changing

while((option != 1) || (option != 2) || (option != 3) || (option != 4))
{
    printf("\n That is not a valid option. Please try again. \n");
    scanf("%d", &option);
}

to something else like

if ((option != 1) || (option != 2) || (option != 3) || (option != 4))
{
    printf("\n That is not a valid option. Please try again. \n");
    // scanf("%d", &option);  // This is probably not required
}

or

if ( option >= 1 && option <= 4)
{
    printf("\n That is not a valid option. Please try again. \n");
    // scanf("%d", &option);
}

Because you are using infinite loop outside, why would you need one inside? All you need is to check the option and show the menu if an unavailable option is selected.

All of your logic you can put in this if afterward, one for each option selected.

---

Better use switch for good understanding

/* After selecting an option */
switch (option)
{
    case 1:
         /* Do the operation according */
         break;

    case 2:
         /* Do the operation according */
         break;

    case 3:
         /* Do the operation according */
         break;

    case 4:
         /* Do the operation according */
         break;

    default:
         /* If none of the option selected */
         printf ("Wrong input! \n")
         break;
}

Hope you got it.

Answer 3

The problem was with the printf function in that it didn't print out until after you had entered the following options, it didn't ask until after the user had answered. A simple flush after the printf sorted this out.