Thread: Switch Statement - Possible Infinite Loop Problem?

Originally Posted by itsme86

Code:

        do
        {
            v += pow(c,2);
            c + 2;
        }while(c <= n);

c + 2 doesn't change the value of c. You want c += 2 instead.

*facepalm* I should have caught that, no wonder it was infinite. Thanks for the fast reply!

Ok, I am having problem with my next case now. (Edited OP).

http://i.imgur.com/kv32d.png Here's a pic to show what I am having problems with.

Originally Posted by itsme86

Could you post the code?

Yea sure

Code:

#include <stdio.h>
#include <math.h>


int display_menu(void);
double compute_factorial(n);


int main()
{
    int n, choice;
    double v, c;


        printf("Enter a whole number, n, between 1-20: ");
        scanf_s("%d", &n); //I'm still not sure why I have to do scanf_s.
        if(n < 1 || n > 20)
        {
        do
        {
            printf("Invalid option: try again. ");
            scanf_s("%d", &n);
        }while(n < 1 || n > 20);
        }
    
    display_menu();


    printf("\nWhat would you like to do? ");
    scanf_s("%d", &choice);


    if(choice < 1 || choice > 6)
    {
    do
        {
            printf("Invalid option: try again. ");
            scanf_s("%d", &choice);
        }while(choice < 1 || choice > 6);
    }


    switch(choice)
    {
    case 1:
        for(c = 1; c <= n; c++)
        {
            printf("%.0lf ", c);
        }
        break;
    case 2:
        for(c = n, v = 0; c >= 1; c--)
        {
            v += c;
        }
        printf("The sum of all whole numbers 0 to n is: %.0lf", v);
        break;
    case 3:
        c = 2;
        v = 0;
        do
        {
            v += (c * c);
            c += 2;
        }while(c <= n);
        printf("The sum of the square of all the even numbers 0 to n is: %.0lf", v);
        break;
    case 4:
        c = 0;
        v = 0;
        do
        {
            v += (1 / c);
            c++;
        }while(c <= n);
        printf("The sum of 1 + 1/2 + ... 1/n. is: %lf", v);
        break;
    case 5:
        v = compute_factorial(n);
        printf("n! is: %.0lf", v);
        break;
    case 6:
        printf("Program will end now.");
        return 0;
        break;
    }


    getch();
    }


int display_menu(void)
{
    printf("\nMenu of Options:\n");
    printf("1.Display numbers 1 to n.\n");
    printf("2.Add up all the numbers 1 to n.\n");
    printf("3.Add up square of all the even numbers 0 to n.\n");
    printf("4.Add up 1 + 1 /2 + ... 1/n.\n");
    printf("5.Compute n!\n");
    printf("6.Quit\n");
    return 0;
    //Input: None.
    //Output: None.
    //Task: Display a "Menu of Options".
}


double compute_factorial(n)
{
    int c;
    double v;


    for(c = 1, v = 1; c <= n; c++)
    {
        v *= c;
    }
    return v;
    //Input Parameter: A whole number
    //Output: Computed n!
    //Task: Compute N!
}

case 4 is what I am having problems with. It ends up saving 1.INF00 for v. :S

Originally Posted by TheBigH

Because you are dividing by zero on the first loop.

/FACEPALM! I did that on a previous lab aswell. I should l2usedebug...