How to decide between using if/else vs try/catch?

Question

When writing code, how does one decide between using if/else or try/catch? For example, in checking for a file, should this be based on if/else (if (File.Exists)) or a try/c

Answer 1

You use try/catch when something unexpected ( an exception ) might happen and you want to do something special about it, like :

try
{
   //Do something that might rise an exception, say a division by 0
   //this is just an easy example as you might want to check if said value is not 0
   //before dividing
   int result = someNumberOfMine / anUnsafeNumber;
}
catch
{
   //if something unexpected happened, do a special treament
}

In your particular case, I would recommand using File.Exists to verify the presence of the file instead of using a try/catch block since the presence or not of the file can be checked before doing anything with it.

Answer 2

Exceptional handling should only be done or used in exceptional cases.

In a scenario which depends on whether a File exists or not it doesn't make sense to use try catch block when simply you can do

if(File.Exists(path))
{
}
else
{

}

Exceptional handling cause a lot of performance hit so try to minimize the exceptional cases by applying more check in your code like if File.Exists(path))

Answer 3

For this you know the file exit problem. So you prefer if else.

If you don't know the problem, better to use try catch.

i suggest the both, like below

try 
{
  if(File.Exists(path)) 
  { 
     do work
  } 
  else 
  {
     messagebox.show("File Path Not Exit");
  } 
}
catch(Exception e) 
{
 messagebox.show(e); 
}

it catch all the errors, which we not think.

Answer 4

You should never use try/catch for flow control.

Generating an exception is an extremely expensive action. If/else is much faster and cleaner.

Answer 5

When the file is expected to not exist, check for existence first. But when the missing file is a unusual state you should indicate this exceptional state with an exception.

So the basic idea is: Try to avoid exceptions on expectable circumstances.

Answer 6

Generally you should do both. try/catch to avoid exceptional situations (file was suddenly deleted from another thread). And if/else to handle non-exceptional (check if file exists). Try/catch is relatively slower than a usual if/else so it does not worth to use it for everything.