(Go Lang) Range (GBEN)

Go by Example


  • Iterate over things and do something

// Here we use range to sum the numbers in a slice. Arrays work like this too.
nums := []int{2, 3, 4}
sum := 0
for _, num := range nums {
  sum += num
fmt.Println("sum:", sum)
// range on arrays and slices provides both the index and value for each
// entry. Above we didn’t need the index, so we ignored it with the blank
// identifier _. Sometimes we actually want the indexes though.
for i, num := range nums {
  if num == 3 {
    fmt.Println("index:", i)
// range on map iterates over key/value pairs.
kvs := map[string]string{"a": "apple", "b": "banana"}
for k, v := range kvs {
  fmt.Printf("%s -> %s\n", k, v)
// range can also iterate over just the keys of a map.
for k := range kvs {
  fmt.Println("key:", k)
// range on strings iterates over Unicode code points. The first value is the
// starting byte index of the rune and the second the rune itself.
for i, c := range "go" {
  fmt.Println(i, c)


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