What is the most common error in a .Net application?

[jith iii]

I think I'm bad in communication :) This was not related to null reference. I just quoted this code when you said about tostring() on integer. Here they could have written the code simply as,

FinalString=String.Format("{0}\{1}\{2}\{3}",value1,value2,value3,value4)

If you want null reference comedy ...here is a gem

IF object1.ToString() <> Nothing Then

End If

[chaiguy1337]

Colin Angus Mackay wrote:

I even saw someone call ToString() on an integer, pass it to a Method and for the method to Parse it back to an integer again. That method was only ever called from one place!

lol

Sad but true: 4/3 of Americans have difficulty with simple fractions. There are 10 types of people in this world: those who understand binary and those who don't. {o,o}.oO( Check out my blog! ) |)””’)          http://pihole.org/ -”-”-

[Colin Angus Mackay]

jith - iii wrote:

If you want null reference comedy

You should read by blog. When I see weird stuff I blog it. Here's one I spotted recently: Formatting Dates the Hard Way[^]

Developer Day Scotland 2 - Free community conference Recent blog posts: *Throwing Exceptions *Training Developers * Method hiding or overriding - or the difference between new and virtual

[jith iii]

Colin Angus Mackay wrote:

Formatting Dates the Hard Way[^]

That was cool :)...i've bookmarked your blog. One cool blog entry similarly i came across is this[^] from Tom kyte's blog. I am not sure if I came to the above link from codeproject itself,then you would have seen it. I was not aware that Tom Kyte is also blogging.

modified on Tuesday, December 16, 2008 3:39 PM

[Member 2956838]

Why not using the famos Nz() function (and if you dont have it build one) G

[franky1987]

Hi all, Thanks to VS2008 I put in all my applications an assembly full of Extension Methods that are so useful when I'm in production. One of these extension method is called 'IsNullOrTrimmedEmpty()'. Actually it just check if a string refence is null and than, if it isn't, if the trimmed value of the string equals to "", and return me a bool value. Not too much advanced, but very helpful!!

[deostroll]

I agree. 2nd to tht tho I used to get those page validation errors, you know when you try to use a rich text editor for your website, and then those DBNull things.

[chaiguy1337]

Can you elaborate on that?

Sad but true: 4/3 of Americans have difficulty with simple fractions. There are 10 types of people in this world: those who understand binary and those who don't. {o,o}.oO( Check out my blog! ) |)””’)          http://pihole.org/ -”-”-

[Kevin McFarlane]

Colin Angus Mackay wrote:

It is perfectly valid in many situations for a reference to be null.

That's true. But one of the things I find most difficult in maintenance programming is figuring out when null is expected and when it isn't - in the absence of developer documentation.

Kevin

[ormonds]

The most common error is that .NET software is written by people who get sidetracked onto software issues and never actually answer the question :laugh:

[Adar Wesley]

Colin Angus Mackay wrote:

There is no double standard. All reference types behave the same way. It is perfectly valid in many situations for a reference to be null. The compiler cannot catch logic errors, only syntax errors. System.Int32 is a value type. It is not valid ever for a value type to be null therefore the compiler can and will catch it for you.

Try this one:

int? value = null;
if (value == null) {
    Console.WriteLine("Value is null");
    Console.WriteLine("type int? is a: {0}", typeof(int?).IsValueType? "ValueType" : "RefType");
}

int? is a value type and is equal to null... And anyway, there sure is a double standard. The double standard is that value types are teated differently then ref types. How about boxing? How about deriving from value types? Don't get me wrong. I am not saying it should be different. Just that there is a difference. --- Adar Wesley

[Colin Angus Mackay]

Adar Wesley wrote:

int? is a value type and is equal to null...

True that int? is a value type True that int? equals null False that int? IS null. Value types still cannot BE null, even if they can EQUAL null. The two concepts are difference. int? is actually syntactic sugar for Nullable<int> which is also a value type. It has internally two fields, hasValue and value. It also overrides the Equals method which checks whether it hasValue or not, if not it compares with null. If you disassemble code that uses nullable types you'll see that it also does inline checks. For example, here is the C# program:

class Program
{
    static void Main(string\[\] args)
    {
        int? a = null;
        int? b = 2;

        Console.WriteLine("A equals B? {0}", a==b);
        Console.ReadLine();
    }
}

And here is what Red Gate's Reflector made of it once the syntactic sugar was stripped away:

private static void Main(string[] args)
{
int? a = new int?();
int? b = new int?(2);
int? CS$0$0000 = a;
int? CS$0$0001 = b;
Console.WriteLine("A equals B? {0}",
(CS$0$0000.GetValueOrDefault() == CS$0$0001.GetValueOrDefault()) &&
(CS$0$0000.HasValue == CS$0$0001.HasValue));
Console.ReadLine();
}

If value types could truely really support being null then none of the above would be necessary.

Adar Wesley wrote:

And anyway, there sure is a double standard. The double standard is that value types are teated differently then ref types. How about boxing? How about deriving from value types?

That's like saying there is a double standard because the CEO of a company that gets a big salary, company car and better benefits than the stock room worker who is on minimum wage. They are doing different jobs.

Developer Day Scotland 2 - Free community conference Recent blog posts: *Throwing Exceptions *Training Developers * Method hiding or overriding - or the difference between new and virtual

[Lashdex]

The function NZ he is referring to is from VB where it replaces a null value. This example returns the value of the variable unless is null then it returns the second parameter: Nz(someVar, "It is null!") It is a coalesce function just like COALESCE(par1, par2,[...]) in SQL. In C# you could use ?? like this: Console.WriteLine(foo.ToString() ?? "Aww, it is null");