C# which is faster do/while or for?

Question

I have a C# .NET 2.0 script and I want to know why the following code would be faster than a do while loop of the same kind.

private double getStop(double avgPrice, bool longTrading)
 {
  double stopS = 0.0;
  double stopL = 0.0;

  for (int i = 0; i < 13; i++)
  {
   if (i == 0 || i == 12)
   {
    stopS = 0.0;
    stopL = 0.0;
   }
   else
   {
    if ((lines[i] - ((lines[i] - lines[i - 1]) / 2)) < avgPrice && avgPrice < (lines[i + 1] - ((lines[i + 1] - lines[i]) / 2)))
    {
     if (avgPrice < lines[i])
     {
      stopL = (lines[i] - ((lines[i] - lines[i - 1]) / 2));
      stopS = lines[i];
     } else {
      stopL = lines[i];
      stopS = (lines[i + 1] - ((lines[i + 1] - lines[i]) / 2));
     }
    }
   }
  }

  if (longTrading)
  {
   return stopL; 
  } else {
   return stopS; 
  } 
 }

Also, would it be faster just to explicitly state each if statement instead of doing them inside of a for loop?

Being that this was answered so fast, why would this run far slower than the above code?

private double getStop(double avgPrice, bool longTrading)
 {
  double stopS = 0.0;
  double stopL = 0.0;

  for (int i = 0; i < 13; i++)
  {
   if (i == 0 || i == 12)
   {
    stopS = 0.0;
    stopL = 0.0;
                skip = true;
   }

   if (!skip && (lines[i] - ((lines[i] - lines[i - 1]) / 2)) < avgPrice && avgPrice < (lines[i + 1] - ((lines[i + 1] - lines[i]) / 2)))
    {
     if (avgPrice < lines[i])
     {
      stopL = (lines[i] - ((lines[i] - lines[i - 1]) / 2));
      stopS = lines[i];
     } else {
      stopL = lines[i];
      stopS = (lines[i + 1] - ((lines[i + 1] - lines[i]) / 2));
     }
    }
   }
           skip = false;
  }

  if (longTrading)
  {
   return stopL; 
  } else {
   return stopS; 
  } 
 }

Answer 1

loop variations aren't too much different, it depends on the context and the programming language.

But my opinion is, for statement don't do until the constaint(s) is/are matched, therefore it should be faster than do/while.

Answer 2

The performance difference should be negligible, but the for loop is clearer so I would go with that.

Answer 3

They should be essentially equivalent. Your 'for' loop gets evaluated as:

int i = 0;
while (i < 13)
{
   //all other stuff
   i++;
};