Chapter 8. Error Sets

Programs fail for many reasons. A file may not exist. Memory allocation may fail. Input may be malformed. A network connection may close unexpectedly.

8 items

Section	Title
1	Error Sets
2	Error Unions
3	Returning Errors
4	`try`
5	`catch`
6	`defer` and `errdefer`
7	Designing Error Boundaries
8	Exercises

Writes › Book › Learn › Learn Zig › Chapter 8. Error Sets ›

Error Sets

Programs fail for many reasons. A file may not exist. Memory allocation may fail. Input may be malformed. A network connection may close unexpectedly.

Writes › Book › Learn › Learn Zig › Chapter 8. Error Sets ›

Error Unions

An error union combines a normal value with an error set.

Writes › Book › Learn › Learn Zig › Chapter 8. Error Sets ›

Returning Errors

A function returns an error the same way it returns a normal value: with return.

Writes › Book › Learn › Learn Zig › Chapter 8. Error Sets ›

`try`

try is a shortcut for a common operation:

Writes › Book › Learn › Learn Zig › Chapter 8. Error Sets ›

`catch`

catch handles an error union.

Writes › Book › Learn › Learn Zig › Chapter 8. Error Sets ›

`defer` and `errdefer`

A program that opens a file must close it. A program that allocates memory must free it. A program that locks a mutex must unlock it.

Writes › Book › Learn › Learn Zig › Chapter 8. Error Sets ›

Designing Error Boundaries

Most functions should not decide what an error means.

Writes › Book › Learn › Learn Zig › Chapter 8. Error Sets ›

Exercises

1. Write a function parseUpper that accepts a byte and returns the uppercase letter value. Return error.InvalidUppercase if the byte is not between 'A' and 'Z'.