index out of range exception

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Hello All,

I have a snippet :

C#

Thread[] t = new Thread[3];
          string[] items = new string[] {"hi","hello","hey"};


          for(int i = 0 ; i <=t.Length; i++) /// When i hover my mouse here then i = 3
          {
              string s = items[i];/// index out of range exception thrown here

              t[i] = new Thread(()=>work(s));
              t[i].IsBackground = true;
              uplist<string> up = new uplist<string>(t[i]);
              up.Add_item(items[i]);

          }

Does this mean that when i say :

for( ;i<=value;) ///here i is assigned the "value" and so in the next iteration i has reached the maximum value and hence it breaks out and throws an exception ?

The moment the loop starts it throws an exception, where as it should throw an exception when i = 3.

Can someone please elaborate on this?

Posted 23-Jan-14 22:57pm

Rahul VB

Updated 24-Jan-14 16:49pm

v2

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Rahul VB 24-Jan-14 22:50pm

Please check question modified

5 solutions

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phil.o · Answer 1 · 2014-01-23T23:43:00

You iterate over the items array using indices from t array.

If they both have the same number of items, that works, but it's only by chance.
Better construct t using length of items.

Correct code would be:

C#

string[] items = new string[] {"hi","hello","hey"};
Thread[] t = new Thread[items.length];
for(int i = 0 ; i < t.Length; i++)
{
   string s = items[i];
   t[i] = new Thread(() => work(s));
   t[i].IsBackground = true;
   uplist<string> up = new uplist<string>(t[i]);
   up.Add_item(items[i]);
}

V5709 · Answer 2 · 2014-01-24T00:54:00

Replace your for loop by

C#

for (int i = 0; i < t.Length; i++) /// When i hover my mouse here then i = 3
{
           string s = items[i];/// index out of range exception thrown here
}

** Because though there are 3 elements in array.. but by default array starts indexing from 0 position. So if you try to find element at 3 rd position it is giving error.

Karthik_Mahalingam · Answer 3 · 2014-01-23T23:01:00

Solution 2

C#

 for (int i = 0; i <= t.Length; i++)

replace it to

C#

for (int i = 0; i < t.Length; i++)

if it is <= it will check upto 3 then it will try to access the fourth index of the array, so you got the index exception..

Posted 23-Jan-14 23:01pm

Karthik_Mahalingam

Updated 23-Jan-14 23:06pm

v2

Comments

Rahul VB 24-Jan-14 5:51am

Yes eventually i did that. But my doubt is what ever i put as the second item in the for loop like suppose

for(;i <= value;) ////am i also assigning that value? which is why, may be it checks for that value also?

Rahul VB 24-Jan-14 22:50pm

Hey please check, i modified the question

Karthik_Mahalingam 24-Jan-14 23:29pm

Hey i am in theatre now, will check after 4 hours.

Karthik_Mahalingam 25-Jan-14 4:47am

int i=0, value=8;
for (; i <= value; )
{
Console.WriteLine(i);
i++;
}
// output :0,1,2,3,4,5,6,7,8

karthik Udhayakumar · Answer 4 · 2014-01-23T23:07:00

Here you go:

C#

Thread[] t = new Thread[3];
          string[] items = new string[] {"hi","hello","hey"};


          for(int i = 0 ; i <t.Length; i++) ///  hover your mouse here 
          {
              string s = items[i];/// pls check if index out of range exception thrown here

              t[i] = new Thread(()=>work(s));
              t[i].IsBackground = true;
              uplist<string> up = new uplist<string>(t[i]);
              up.Add_item(items[i]);

          }

Write back if it throws error:)

TrushnaK · Answer 5 · 2014-01-23T23:08:00

Solution 4

or try:-

for(int i = 0 ; i <=t.Length; i++)

to

for(int i = 0 ; i <=t.Length -1; i++)

Posted 23-Jan-14 23:08pm

TrushnaK

index out of range exception

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