Question

What would a piece of code which “uses exceptions to control flow” look like? I’ve tried to find a direct C# example, but cannot. Why is it bad?

Thanks

Answer 1

Bad

The below code catches an exception that could easily be avoided altogether. This makes the code more difficult to follow and typically incurs a performance cost as well.

int input1 = GetInput1();
int input2 = GetInput2();

try
{
    int result = input1 / input2;
    Output("{0} / {1} = {2}", input1, input2, result);
}
catch (OverflowException)
{
    Output("There was an overflow exception. Make sure input2 is not zero.");
}

Better

This code checks for a condition that would throw an exception, and corrects the situation before the error occurs. This way there is no exception at all. The code is more readable, and the performance is very likely to be better.

int input1 = GetInput1();
int input2 = GetInput2();

while (input2 == 0)
{
    Output("input2 must not be zero. Enter a new value.");
    input2 = GetInput2();
}

int result = input1 / input2;
Output("{0} / {1} = {2}", input1, input2, result);