"Use of unassigned local variable" error C#, "while" command

Question

While writing my code, I received this error for a,b and c.

           while(n==0)
        {
            a = Convert.ToInt32(Console.ReadLine());
            b = Convert.ToInt32(Console.ReadLine());
            c = Convert.ToInt32(Console.ReadLine());
            n=CheckTriang(a, b, c, n);

        }

        x=RightTriang(a, b, c, x);

I input a, b and c's values in the loop, then check them in the working method CheckTriang (determining if the values can make a valid triangle), and break the condition, returning n=1. I think that the problem might be with the compiler not being sure if the loop will even stop to give the values. How can I rewrite the code to be clearer?

Thanks in advance!

Edit: I only copied the problematic part, not the whole code. The needed variables are declared.

can we see the part where you define and initialize a,b,c and n? — Jacob Mattison
– Jacob Mattison, Commented Nov 15, 2013 at 21:28
Can you please post a working example so that we can test your code? — Stefan Bollmann
– Stefan Bollmann, Commented Nov 15, 2013 at 21:29
Where are you assigning a value to x? Your very last line tries to use a value named x but as far as we can tell it has no value. Set some break points and step through your code line by line. Verify everything has a value. — sab669
– sab669, Commented Nov 15, 2013 at 21:34

Aric TenEyck · Accepted Answer · 2013-11-15 21:30:07Z

6

Switch to a do-while loop:

do {
        a = Convert.ToInt32(Console.ReadLine());
        b = Convert.ToInt32(Console.ReadLine());
        c = Convert.ToInt32(Console.ReadLine());
        n=CheckTriang(a, b, c, n);
    } while (n == 0)

This guarantees that you'll get through the loop at least once.

answered Nov 15, 2013 at 21:30

Aric TenEyck

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Comments

iamkrillin · Accepted Answer · 2013-11-15 21:30:38Z

3

The problem is that if n==0 on the first run a,b,c,& n would never be initialized. The compiler is catching this and warning you as such. Simply add

int a=0, b=0, c=0, n=0;

somewhere above your while loop

answered Nov 15, 2013 at 21:30

iamkrillin

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Comments

Reed Copsey · Accepted Answer · 2013-11-15 21:29:31Z

1

Make sure, when you declare n, that you initialize it:

int n = 0; // Add the = 0

answered Nov 15, 2013 at 21:29

Reed Copsey

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3 Comments

therealtbs Over a year ago

Structs are initialized with their default values though. So int n = 0; is the same as int n;

Grandsaga Over a year ago

The error is for a, b and c, everything else is working fine. I only copied a specific part. Thanks anyway.

James Over a year ago

@therealtbs While its true the value will be zero, and you could dynamically access it at run time, you'll have compile problems if you try compiling something like int n; bool x = n == 0;

David S. · Accepted Answer · 2013-11-15 21:31:17Z

1

You need to declare your variables by indicating their type, and also initialize n before you use it.

int n = 0;
while(n == 0)
{
    int a = Convert.ToInt32(Console.ReadLine());
    int b = Convert.ToInt32(Console.ReadLine());
    int c = Convert.ToInt32(Console.ReadLine());
    n = CheckTriang(a, b, c, n);
}

//replace 'var' by whichever type 'RightTriang' returns.
var x = RightTriang(a, b, c, x);

answered Nov 15, 2013 at 21:31

David S.

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