C#•3mo ago

✅ Exceptions

Are exceptions essentially if statements that are global across the entire program?

14 Replies

Such as if I’m dividing by 0 somewhere, I can make an exception that handles that specific problem across my entire program?

Pobiega•3mo ago

uh Not as such, no an exception is an object that represents an error of some sort, and they "bubble up" until caught if you never catch it, it will terminate your program with an error are you familar with whats called "the call stack"?

Merineth 🇸🇪OP•3mo ago

Exceptions are ‘’try’’ and ‘’catch’’ right?

Pobiega•3mo ago

no those are keywords that relate to exceptions exceptions are C# objects that inherit from the Exception class

Merineth 🇸🇪OP•3mo ago

Ok so an exception class is a class that’s meant to catch possible problems?

Pobiega•3mo ago

no, it represents an instance of the problem hang on, let me write some demo code

Merineth 🇸🇪OP•3mo ago

Merineth 🇸🇪OP•3mo ago

So instead of crashing the entire program it will give an exception instead with try and catch?

Pobiega•3mo ago

try
{
    // here is where we do dangerous stuff that might throw exceptions
    var y = 0;
    var x = 5 / y; // this will cause an error, specifically a `DivideByZeroException`
}
catch (DivideByZeroException ex)
{
    // here we write code that can handle the particular exception
    Console.WriteLine("You can't divide by zero!");
}

try
{
    // here is where we do dangerous stuff that might throw exceptions
    var y = 0;
    var x = 5 / y; // this will cause an error, specifically a `DivideByZeroException`
}
catch (DivideByZeroException ex)
{
    // here we write code that can handle the particular exception
    Console.WriteLine("You can't divide by zero!");
}

Merineth 🇸🇪OP•3mo ago

So we have to know beforehand what kind of error will occur to catch it?

Buddy•3mo ago

I mean you can use

try
{

}
catch (Exception ex)
{

}

try
{

}
catch (Exception ex)
{

}

Which catches all exceptions, but generally not recommended. If you can try to avoid methods that can throw exceptions all-together

Merineth 🇸🇪OP•3mo ago

This does make senses tho Ok so it’s generally better to know what problem could occur to catch that specific problem? What would code look like if I want to catch multiple errors that could occur?

try
{
}
catch (Exception1, Exception2) 
{
}

try
{
}
catch (Exception1, Exception2) 
{
}

Like this?

Pobiega•3mo ago

try
{
    // here is where we do dangerous stuff that might throw exceptions
    var y = 0;
    var x = 5 / y; // this will cause an error, specifically a `DivideByZeroException`
}
catch (DivideByZeroException ex)
{
    Console.WriteLine("You can't divide by zero!");
}
catch (InvalidOperationException ex)
{
    Console.WriteLine("An invalid operation was performed!");
}

try
{
    // here is where we do dangerous stuff that might throw exceptions
    var y = 0;
    var x = 5 / y; // this will cause an error, specifically a `DivideByZeroException`
}
catch (DivideByZeroException ex)
{
    Console.WriteLine("You can't divide by zero!");
}
catch (InvalidOperationException ex)
{
    Console.WriteLine("An invalid operation was performed!");
}

like this its pretty rare that you catch two or more exceptions with the exact same fix and if you do, you can use...

catch (Exception ex) when (ex is DivideByZeroException or InvalidOperationException)
{
    Console.WriteLine("You can't divide by zero or perform invalid operations!");
}

catch (Exception ex) when (ex is DivideByZeroException or InvalidOperationException)
{
    Console.WriteLine("You can't divide by zero or perform invalid operations!");
}

but this is very rare, as said

Merineth 🇸🇪OP•3mo ago

Ok thanks I think I understand it now :)

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✅ Exceptions