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