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Yes. These examples are designed to be copied and adapted to your own code.

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Open the Go compiler from the main playground catalog, then paste or write any code you want to run.

Go code examples · runnable

20 runnable Go code examples.

Open any Go example to explore the code and run it online. No setup, no signup.Explore practical Go code examples with clear explanations. Open any example to edit and run it online — no setup, no signup.

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20 of 100 examples

Go

How to reverse a string in GoReverse a string in Go the Unicode-safe way — []rune plus a two-pointer swap, slices.Reverse, and strings.Builder — plus why reversing []byte corrupts non-ASCII text.How to convert a string to an int in GoConvert a string to an int in Go with strconv.Atoi — plus ParseInt for hex, binary, and bit sizes, ParseFloat for decimal strings, and how to handle bad input and overflow the idiomatic way.How to check if a key exists in a map in GoCheck if a key exists in a Go map with the comma-ok idiom — v, ok := m[key] — plus the zero-value trap, existence-only sets with map[string]struct{}, value lookups, and how nil maps behave.How to check if a slice contains an element in GoCheck if a Go slice contains a value with slices.Contains (Go 1.21+), the classic loop for older code, slices.ContainsFunc for custom matches, slices.Index when you need the position, and a map set for repeated lookups.How to sort a slice in GoSort a Go slice with slices.Sort (Go 1.21+), order structs and custom keys with slices.SortFunc and cmp.Compare, sort.Slice for older code, stable multi-key sorts, and how to sort without mutating the original.How to remove an element from a slice in GoRemove an element from a Go slice with slices.Delete (Go 1.21+), the classic append(s[:i], s[i+1:]...) idiom, O(1) swap-with-last removal when order does not matter, slices.DeleteFunc for bulk filtering, and the aliasing trap that leaks memory.How to check if a string contains a substring in GoCheck whether a Go string contains a substring with strings.Contains — plus HasPrefix/HasSuffix for anchored checks, ContainsAny and ContainsRune for character sets, Index when you need the position, and how to search case-insensitively when there is no ContainsFold.How to split a string in GoSplit a string in Go with strings.Split — plus strings.Fields for whitespace, SplitN to cap the pieces, strings.Cut for key=value, bufio.Scanner for lines, and FieldsFunc/regexp for several delimiters at once.How to concatenate strings in GoConcatenate strings in Go with + for a couple of pieces, strings.Builder inside a loop, and strings.Join for a []string — plus fmt.Sprintf for formatting, bytes.Buffer for byte output, and why += in a loop is O(n²).How to trim whitespace from a string in GoTrim whitespace from a string in Go with strings.TrimSpace — plus custom cutsets with Trim, the TrimLeft-vs-TrimPrefix trap, TrimFunc for zero-width characters, and collapsing inner whitespace with Fields + Join.How to convert an int to a string in GoConvert an int to a string in Go with strconv.Itoa — plus FormatInt for other bases, fmt.Sprintf for padded output, why string(65) gives "A" not "65", and how to build strings from many ints without O(n²) concatenation.How to iterate over a map in GoIterate over a Go map with for k, v := range m — plus keys-only and values-only loops, why the iteration order is deliberately randomised, how to get a stable order with slices.Sorted(maps.Keys(m)), sorting by value, and what is legal to change while the loop runs.How to remove a key from a map in GoRemove a key from a Go map with the delete builtin — plus why deleting a missing key is a safe no-op, deleting while ranging, clear() vs make() vs nil, and why delete never gives the memory back.How to remove duplicates from a slice in GoRemove duplicates from a Go slice with a map[T]struct{} seen-set that preserves first-seen order, or slices.Sort + slices.Compact when sorted output is fine — plus CompactFunc for case-insensitive dedupe, deduping structs by a key field, and the zero-allocation s[:0] filter.How to loop with an index in GoLoop with an index in Go — for i, v := range s, the index-only and value-only forms, the classic three-clause loop for backwards and custom steps, why ranging a string gives byte offsets, and the Go 1.22 loop-variable change.How to convert a struct to JSON in GoTurn a Go struct into JSON with json.Marshal — plus struct tags for key names, omitempty and hidden fields, MarshalIndent for pretty output, nested structs, maps and time.Time, and streaming with json.Encoder.How to parse JSON into a struct in GoParse JSON into a Go struct with json.Unmarshal — struct tags and field matching, JSON arrays and nested objects, map[string]any for unknown payloads, pointer fields to tell missing from zero, and json.Decoder for strict parsing.How to format a date in GoFormat a date in Go with t.Format and the reference-time layout "2006-01-02 15:04:05" — why it is that date, the predefined layouts like time.RFC3339 and time.DateOnly, parsing back with time.Parse, 12-hour clocks and padding, and time zones.How to wait for goroutines to finish in GoWait for goroutines to finish in Go with sync.WaitGroup — Add, Done and Wait — plus why a bare go f() prints nothing, how to collect results without a data race, mutex and atomic counters, channel fan-in, and errgroup-style error handling with only the standard library.How to handle errors in GoHandle errors in Go the idiomatic way — check err != nil and return early, add context with fmt.Errorf and %w, match sentinels with errors.Is, pull typed errors out with errors.As, join several failures with errors.Join, and know when panic/recover is the wrong tool.

Questions & answers

Examples, explained

Yes. Open any Go example to edit and run its code on the CompileBytes engine without installing anything.