Question

When must we use checked operator in C#?
Is it only suitable for exception handling?

Answer 1

You would use checkedto guard against a (silent) overflow in an expression.
And use unchecked when you know a harmless overflow might occur.

You use both at places where you don’t want to rely on the default (project-wide) compiler setting.

Both forms are pretty rare, but when doing critical integer arithmetic it is worth thinking about possible overflow.

Also note that they come in two forms:

 x = unchecked(x + 1);    // ( expression )
 unchecked { x = x + 1;}  // { statement(s) }