if string item is not in string array

Question

I have a string array. I need to display buttons based on if the selected item is in the array. I need to know how to tell the program if "(array.NOT Contains("string"))". Please can anybody help me?? Thanks in advance

My code:

    List<string> activationids = new List<string>();
    foreach (ModuleActivation moduleactivation in activationid)
         activationids.Add(moduleactivation.ActivationID);

    string gvselectActID = GridView1.SelectedRow.Cells[1].Text;

    if (activationids.Contains(gvselectActID))
    {
      activateInsert.Visible = true;
      activateUpdate.Visible = false;
      deactivate.Visible = true;
    }
    else if (activationids."NOT" Contains(gvselectActID))
    {
      activateInsert.Visible = false;
      activateUpdate.Visible = true;
      deactivate.Visible = false;
    }
    else
    {
     activateInsert.Visible = false;
     activateUpdate.Visible = false;
     deactivate.Visible = false;
    }
  }

You need to understand boolean logic better - the if/else if/else construct you have does not make sense with the test condition you have. — Oded
– Oded, Commented Aug 13, 2010 at 8:14

Neil Knight · Accepted Answer · 2010-08-13 08:12:02Z

10

Change:

else if (activationids."NOT" Contains(gvselectActID))

to

else if (!activationids.Contains(gvselectActID))

answered Aug 13, 2010 at 8:12

Neil Knight

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Comments

cjk · Accepted Answer · 2010-08-13 08:21:24Z

6

Or even simpler

bool containsItem=activationids.Contains(gvselectActID);

activateInsert.Visible = containsItem;
activateUpdate.Visible = !containsItem;
deactivate.Visible = containsItem;

edited Aug 13, 2010 at 8:21

cjk

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answered Aug 13, 2010 at 8:19

Alex

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1 Comment

cjk Over a year ago

+1: Whilst it doesn't specifically answer the question, it is the best approach to the sample code as a whole.

thelost · Accepted Answer · 2010-08-13 08:11:16Z

2

The ! means "NOT". So you have to place it in front of the expression you need to negate;

!activationids.Contains("blahblah");

However, it's quite clear that if activationids.Contains("blahblah") is false, you are gonna go into the second case. Also, currently, your third block (... else { ...) will never be hit.

answered Aug 13, 2010 at 8:11

thelost

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Comments

cjk · Accepted Answer · 2010-08-13 08:12:21Z

2

There are two very straightforward ways to do this:

Not the result of the bool function call:

if(!activationids.Contains(gvselectActID))
Check the result and compare it to false

if(activationids.Contains(gvselectActID) == false)

However, you are checking if it contains it in the first if() clause, which means that the first else clause will be fired if it isn't contained. There is no need to check, and there is no way that the third else will ever be fired.

answered Aug 13, 2010 at 8:12

cjk

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Comments

Kikaimaru · Accepted Answer · 2010-08-13 08:20:51Z

2

Contains returns true or false, sou you cannot have three branches, you can do just

if (activationids.Contains(gvselectActID)) // it does contain
  ...
else // it does not contain
  ...

there are no other possibilities

[joke]
well it could work in this case
http://thedailywtf.com/Articles/What_Is_Truth_0x3f_.aspx
[/joke]

edited Aug 13, 2010 at 8:20

answered Aug 13, 2010 at 8:15

Kikaimaru

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1 Comment

Jon Hanna Over a year ago

if(x){doSomething();} else if(!x){doSomethingElse();} else {throw new LogicalBoundsOfUniverseExceededException();} (though strictly , if x is changed from the outside by another thread, the third condition could be hit).

Oded · Accepted Answer · 2010-08-13 08:16:13Z

1

This will be enough:

if (activationids.Contains(gvselectActID))
{
  // Goes here if condition is true
  activateInsert.Visible = true;
  activateUpdate.Visible = false;
  deactivate.Visible = true;
}
else
{
  // Goes here if condition is false
  activateInsert.Visible = false;
  activateUpdate.Visible = true;
  deactivate.Visible = false;
}

There are no other possible options - there can't be a third branch.

This makes no sense:

if(booleanCondition)
{}
else if (!booleanCondition)
{}
else
{}

As by definition, if the booleanCondition is false, the else branch will be taken - there is no need to test for it being false.

answered Aug 13, 2010 at 8:16

Oded

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