what does it mean by "not all code paths returns a value"?

Question

1.50/5 (2 votes)

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this code gives an error on col1_button_click(int count), "not all code paths returns a value"
what does it mean?how can i remove this error?pls can any one help me?

C#

public int returnVal1;

private void button1_Click(object sender, EventArgs e)
{
    returnVal1= col1_button_click(clickCountC1);
}

private int col1_button_click(int count)
{
    if (count == 0)
    {
        count = 1;
        return count;
    }
    else if (count == 1)
    {
        count = 2;
        return count;
    }
    else if (count ==2)
    {
        count = 0;
        return count;
    }

}

Posted 5-Jul-11 5:14am

Member 7779792

Updated 5-Jul-11 5:47am

#realJSOP

v5

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Comments

#realJSOP 5-Jul-11 11:49am

Stop changing it back to the original version. All I did was put the pre block around it so it would show up as a block of code. This is a standard Codeproject style, and you would do well to learn about it if you intended to keep posting here.

4 solutions

Solution 3

What happens when count is, say, 3?
In that case your code will not return anything - and that is exactly what the error means.

Every case must be covered while using a return statement.

Posted 5-Jul-11 6:39am

Abhinav S

Updated 6-Jul-11 10:02am

v2

Comments

Sergey Alexandrovich Kryukov 5-Jul-11 14:17pm

Nice explanation, a 5.
--SA

Abhinav S 5-Jul-11 14:41pm

Thank you.

Sergey Alexandrovich Kryukov 6-Jul-11 16:03pm

I just fixed capitalization and added '?' in first line. Do you mind?
--SA

Abhinav S 7-Jul-11 3:23am

No problem. Thanks for fixing the answer.

Sergey Alexandrovich Kryukov 8-Jul-11 1:33am

My pleasure.
--SA

Espen Harlinn 7-Jul-11 14:25pm

Nice reply - my 5

Abhinav S 7-Jul-11 14:27pm

Thank you Espen.

Solution 2

It means you need a return statement just before the last curly brace.

BTW, I'd do the same method this way:

C#

private int col1_button_click(int count)
{
    count++;
    if (count >= 2)
    {
        count = 0;
    }
    return count;
}

It's bad practice to have more than one exit point in a method. Whenever possible, you should avoid it.

Posted 5-Jul-11 5:22am

#realJSOP

Updated 5-Jul-11 5:27am

v2

Comments

Peter Mulholland 5-Jul-11 11:54am

++count;
as you're not using the value before the increment,
but I assume this gets optimized out anyway.

#realJSOP 5-Jul-11 13:03pm

It doesn't matter, because it does get optimized out.

Peter Mulholland 5-Jul-11 16:34pm

I wouldn't say it doesn't matter, using the correct option demonstrates an understanding of the difference between the 2, (not for a second suggesting you don't John) even tho we should never have to worry about the cost of the post increment any more. It's good practice to write what you mean and use the best tool for the job.

BobJanova 7-Jul-11 7:03am

private int col1_button_click(int count){
return ++count % 3;
}

I don't actually agree that multiple return points are bad practice in all cases. (In particular 'guard' returns at the top of a method are clear and useful, and a switch where every case is a return or throw inside a simple method is not a problem.) But you are dead on with this example.

Solution 1

what is clickCountC1 in this line col1_button_click(clickCountC1);? I think you are passing wrong/insufficient value to col1_button_click(int count) method. where is clickCountC1 defined?

And do this:

C#

private int col1_button_click(int count)
{
if (count == 0)
{
   count = 1;
   return count;
}
else if (count == 1)
{
   count = 2;
   return count;
}
else if (count ==2)
{
   count = 0;
   return count;
}
return count;
}

hope this helps :)

Posted 5-Jul-11 5:22am

Uday P.Singh

Updated 5-Jul-11 7:27am

v4

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CPallini · Accepted Answer · 2011-07-05T07:52:00

Solution 4

It means: "in your function there is at least one path without a return statement. Now, since you have declared it returning something, you're a liar and I won't compile it".

Posted 5-Jul-11 7:52am

CPallini

Comments

Uday P.Singh 5-Jul-11 13:56pm

good one my 5!

Sergey Alexandrovich Kryukov 5-Jul-11 14:17pm

Best explanation so far, to my taste :-) A 5.
--SA