Programming Languages - Error Handling

Last Updated: 2024-01-21

By Language

C++

In C and similar languages, it is common for functions to return values like -1, null, or the empty string to signal errors or missing results. This is known as in-band error handling.

In C, a write error is signaled by a negative count with the error code secreted away in a volatile location. In Go, Write can return a count and an error.

C++ does have exceptions, however Google C++ Style Guide does not allow exceptions. (https://google.github.io/styleguide/cppguide.html#Exceptions)

try {
  // ...
} catch(string &err) {
  // ...
}

No finally block.

Java

Java has both checked (compile-time errors) and unchecked exceptions (runtime errors).

Checked exceptions must be explicitly caught or declared by the developers to be thrown or instantly fixed.

try {
  // ...
} catch(Exception e) {
  // ...
} finally {
  // ...
}

Throw:

throw new RuntimeException("Something is wrong.");

Kotlin

Kotlin does not have checked exceptions

Go

The error built-in interface:

type error interface {
    Error() string
}

Pattern:

// Define your own error.
type MyError struct {
	When time.Time
	What string
}

// Implement the `error` interface.
func (e *MyError) Error() string {
	return fmt.Sprintf("at %v, %s",
		e.When, e.What)
}


// Your func signature should return an `error`
func foo() error {
  // If something happens, return `MyError`:
  return &MyError{
		time.Now(),
		"it didn't work",
	}
}

// Catch and deal with the error.
if err := foo(); err != nil {
  // ...
}

Do not use panic for normal error handling.

Within package main and initialization code, consider log.Exit for errors that should terminate the program.s

Rust

Rust does not allow throwing exceptions, instead Rust handles errors through its return type.

match safe_div(1.0, 0.0) {
    Ok(v) => { println!("{}", v); },
    Err(err) => { println!("{}", err); }
}

Python

Python does not distinguish between checked and unchecked exceptions.

Throw

raise ValueError('some error message')

Catch

try:
    code_that_may_raise_exception()
except ValueError as err:
    print(err.args)

Ruby

• begin/end
• rescue keyword
• ensure
• raise