Golang Range: The Complete Guide to Iteration

In Golang, the range keyword can be used to iterate over data structures such as arrays, slices, maps, and channels.具體使用方法如下：

1. Iterating through arrays and slices:

arr := []int{1, 2, 3, 4, 5}
for idx, val := range arr {
    fmt.Printf("Index: %d, Value: %d\n", idx, val)
}

1. Iterative mapping:

m := map[string]int{"a": 1, "b": 2, "c": 3}
for key, val := range m {
    fmt.Printf("Key: %s, Value: %d\n", key, val)
}

1. Iterative channel.

ch := make(chan int)
go func() {
    ch <- 1
    ch <- 2
    ch <- 3
    close(ch)
}()

for val := range ch {
    fmt.Println(val)
}

During the iteration process, the range keyword will return two values, which are the index (or key) and the corresponding value. You can choose to use a variable to receive one of the values, or use an underscore _ to discard the value that is not needed.