Go quick reference

The smallest Go program: package main, func main() and fmt.Println.

var and :=, the basic types, constants, zero values and converting between types with strconv.

if / else, switch, and for — Go's only loop — with a counter, a condition or range.

Define functions with func, return several values, and return an error instead of throwing.

Grow a slice with append, look up a map with the comma-ok form, and sort with slices and sort.

Group fields in a struct, attach methods, and accept any type that has the right methods with an interface.

The strings package, formatting with fmt.Sprintf, bytes vs runes, and regular expressions with regexp.

Run functions concurrently with go, wait with sync.WaitGroup, and pass results over a channel.

Read what you type in the IDE's Input tab with fmt.Fscan or line by line with bufio.Scanner.

Read project files with os.ReadFile or os.Open, parse CSV and JSON, and write temporary files under /tmp.

Split package main over several files in one folder; what the standard library offers without installing anything.

What Run builds, the time limit, input, tests, and what a run cannot do.

Compile errors such as declared and not used and undefined, and runtime panics such as index out of range and nil map.

Where to read more: A Tour of Go, Effective Go, the standard library and the language specification.