Question

When writing a C# application whose #1 priority is to never crash, how often should I used a try-catch block?

Can I encapsulate all the statements in a method in try-catch blocks?

public void SomeMethod() {     try     {         // entire contents of the function         // library calls         // function calls         // variable initialization .. etc     }     catch (Exception e)     {         // recover     } } 

What are the downsides to wrapping everything in try-catch blocks?

Answer 1

The only down side is when an exception is actually thrown. There is no overhead for wrapping the code, except for when exceptions occur.

Also, you don’t want to use try/catch for control flow. Consider this (bad code):

try {      FileStream fs = File.Open('somefile.txt', FileMode.Open);  } catch (Exception ex) {     MessageBox.Show('The file does not exist. Please select another file'); } 

You’ll get more performance from some thing like File.Exists. such as:

if(!File.Exists('somefile.txt'))   MessageBox.Show('The file does not exist.') 

EDIT: found the MSDN direct quote:

Finding and designing away exception-heavy code can result in a decent perf win. Bear in mind that this has nothing to do with try/catch blocks: you only incur the cost when the actual exception is thrown. You can use as many try/catch blocks as you want. Using exceptions gratuitously is where you lose performance. For example, you should stay away from things like using exceptions for control flow.