CODEWITHSUNDEEP
c#
Óûth Mânē
Óûth Mânē

Reputation: 59

Why my Bool value changes in catch block even if there was no error?

I'm still learning c# and came across this problem , i wanted to make a program that make sure that the user enters an integer . but when i do this , i'm stuck in an infinite loop . Why the the bool b; variable change its value in catch block even if the user typed an integer ? My code : 

class MainClass
{
    public static void Main (string[] args)
    {
        int n= 0;
        bool b = true;
        do {
            try {
                Console.WriteLine ("Enter an integer : ");
                n = Convert.ToInt32 (Console.ReadLine ());
            } catch (Exception e) {
                Console.WriteLine (e.Message);
                b = false;
            } finally {
                Console.WriteLine (n);
            }
        } while(b == false);
    }
}

but i fixed the problem when i did this : 

class MainClass
{
    public static void Main (string[] args)
    {
        int n= 0;
        bool b;
        do {
            try {
                b = true;
                Console.WriteLine ("Enter an integer : ");
                n = Convert.ToInt32 (Console.ReadLine ());
            } catch (Exception e) {
                Console.WriteLine (e.Message);
                b = false;
            } finally {
                Console.WriteLine (n);
            }
        } while(b == false);
    }
}

can someone explain please ?

Upvotes: 0

Views: 592

Answers (2)

tony
tony

Reputation: 1651

The b variable is trapped as false forever, if the user doesn't enter a correct input. So, in the beginning of every loop the boolean variable needs to be set as "true" which was its default value. That is because every iteration should be a new try for the user to enter an integer.

Upvotes: 4

hawkstrider
hawkstrider

Reputation: 4341

You can easily do this just by using int.TryParse without a try catch block

static void Main (string[] args)
{
    int n= 0;
    bool b;
    do {
        Console.Write ("Enter an integer : ");
        b = int.TryParse(Console.ReadLine (), out n);
    } while(!b);
    //int has been entered, now do something else...
}

You can simplify it even further by not even introducing the bool variable

static void Main (string[] args)
{
    int n;
    do {
        Console.Write ("Enter an integer : ");
    } while(!int.TryParse(Console.ReadLine (), out n));
    //int has been entered, now do something else...
}

Upvotes: 2

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