Why aren't variables declared in “try” in scope in “catch” or “finally”?

Question

In C# and in Java (and possibly other languages as well), variables declared in a \"try\" block are not in scope in the corresponding \"catch\" or \"finally\" blocks. For e

Answer 1

In the specific example you've given, initialising s can't throw an exception. So you'd think that maybe its scope could be extended.

But in general, initialiser expressions can throw exceptions. It wouldn't make sense for a variable whose initialiser threw an exception (or which was declared after another variable where that happened) to be in scope for catch/finally.

Also, code readability would suffer. The rule in C (and languages which follow it, including C++, Java and C#) is simple: variable scopes follow blocks.

If you want a variable to be in scope for try/catch/finally but nowhere else, then wrap the whole thing in another set of braces (a bare block) and declare the variable before the try.