What's wrong in the following code

Question

1.00/5 (2 votes)

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C#

public static void Main(string[] args)         
        {             // Retry three times on failure to open file.             
            int retryCount = -1;            
            String line = null;             
            do              
            {                 
                try                  
                {                     
                    StreamReader reader = new StreamReader("Test.txt");                     
                    line = reader.ReadLine();                     
                    reader.Close();                 
                }                  
                catch (IOException)                  
                {                     
                    // Wait a little bit.                     
                    Thread.Sleep(300);                      
                    if (retryCount == -1) {                         
                        // Start the count at three if this is the first occurrence.                         
                        retryCount = 3;                     
                    } 
                    else 
                    {                         
                        // Okay, looks like somebody has tried before.                         
                        retryCount--;                     
                    }                 
                }             
            }              
            while (retryCount > 0);        
 }

Posted 30-Aug-14 17:27pm

Member 11047851

Updated 31-Aug-14 18:44pm

VICK

v2

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5 solutions

Solution 5

1. Instead of using reader.close() use "using" block. Read more at http://msdn.microsoft.com/en-IN/library/yh598w02.aspx[^]

2. If you are NOT using the "using" block, close the connection in finally block. Like:

C#

StreamReader reader = new StreamReader("Test.txt");
            try
            {
                //StreamReader reader = new StreamReader("Test.txt");
                var line = reader.ReadLine();
            }
            catch (IOException)
            {
            }
            finally
            {
                reader.Close();
            }

Read more at http://msdn.microsoft.com/en-IN/library/zwc8s4fz.aspx[^]

3. Avoid using Thread.Sleep() because it's harmful. Read at http://stackoverflow.com/questions/8815895/why-is-thread-sleep-so-harmful[^]

Apart from using "using" block and "Thread.Sleep(300)" problems, as the comment says it should try 3 times after the IO read fails. But actually it runs 4 times. I think this might be a point here as it is used in a do...while loop.

Hope it helps.

Posted 1-Sep-14 15:50pm

Dukhabandhu Sahoo

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Tadit Dash (ତଡିତ୍ କୁମାର ଦାଶ) · Accepted Answer · 2014-08-30T17:53:00

Solution 1

Why would somebody do that for you?

If you have written this code, you are the best person to debug and find out the issue. How we would know the problem without even getting what is the requirement?

Here we try to answer and solve specific problems people face during programming. :)

Posted 30-Aug-14 17:53pm

Tadit Dash (ତଡିତ୍ କୁମାର ଦାଶ)

Comments

Member 11047851 30-Aug-14 23:57pm

Thanks Tadit

Tadit Dash (ତଡିତ୍ କୁମାର ଦାଶ) 31-Aug-14 0:06am

Welcome. :)

Sergey Alexandrovich Kryukov · Accepted Answer · 2014-08-30T19:35:00

Sorry, this code is impossibly bad. Why doing all that stuff. Every time you say Thread.Sleep(300); especially with hard-coded "300", the question would be: "why not 310, why not 200?". If fact, it all makes no sense at all.

C#

string fileName = //... never a hard-coded file name

//...

using (StreamReader reader = new StreamReader(fileName)) {
   string someData = reader.ReadLine();
   // ... whatever you need to read
} // here, reader.Dispose is automatically called
// read about "using" statement

And nothing else. There is no need to retry. Instead, do some effort to work with the files not touched by other processes. But it the file is opened by some other process, retrying is just silly. Instead, stop trying immediately.

Don't use try-catch on too local level. Do it when you really know what to do with the exception (I call it "competency points"), often only on the very top stack frame of the thread. Exception have been invited to isolate exception handling, not to mix them with code.

—SA

majid torfi · Accepted Answer · 2014-08-31T03:56:00

C#

public static void Main(string[] args)
{
// Retry three times on failure to open file.
int retryCount = -1;
String line = null;
do
   {
     try
         {
              StreamReader reader = new StreamReader("Test.txt");
              line = reader.ReadLine();
              reader.Close();
           }
      catch (IOException)
           {
          // Wait a little bit.
          Thread.Sleep(300);
     if (retryCount == -1)
     {
          // Start the count at three if this is the first occurrence.
          retryCount = 3;
     }
     else
    {
        // Okay, looks like somebody has tried before.
        retryCount--;
    }

         }
  }
while (retryCount > 0);
  }

reader.Close();
new StreamReader(@"c:\Test.txt");
is loop and hangover your pc

Sergey Alexandrovich Kryukov · Accepted Answer · 2014-08-31T08:56:00

Solution 4

Member 11047851 wrote:
Thanks Sergey. This question was asked in the interview and i couldn't figure it out.

As to the interview preparation, see also my past answer:
SSRS interview questions and answers[^].

—SA

Posted 31-Aug-14 8:56am

Sergey Alexandrovich Kryukov