Go range

In Go, the range keyword is used to iterate over the elements of an array, slice, string, or map. The range keyword can be used in a for loop to iterate over the elements of a collection one by one.

The syntax of the range keyword is as follows:

for index, value := range collection {
    // code to be executed
}

The index variable represents the index of the current element in the collection, and the value variable represents the value of the current element. The loop body contains the code to be executed for each element in the collection.

Here's an example of using the range keyword to iterate over an array in Go:

arr := [5]int{1, 2, 3, 4, 5}
for i, val := range arr {
    fmt.Println(i, val)
}

In this example, the range keyword is used to iterate over the elements of the array arr. The loop variable i represents the index of the current element, and val represents the value of the current element. The loop body prints both the index and value of each element to the console.

The range keyword can also be used to iterate over the elements of a slice:

s := []string{"apple", "banana", "cherry"}
for i, val := range s {
    fmt.Println(i, val)
}

In this example, the range keyword is used to iterate over the elements of the slice s. The loop variable i represents the index of the current element, and val represents the value of the current element. The loop body prints both the index and value of each element to the console.

The range keyword can also be used to iterate over the characters of a string:

str := "hello"
for i, ch := range str {
    fmt.Println(i, ch)
}

In this example, the range keyword is used to iterate over the characters of the string str. The loop variable i represents the index of the current character, and ch represents the value of the current character. The loop body prints both the index and value of each character to the console.

Finally, the range keyword can also be used to iterate over the key-value pairs of a map:

m := map[string]int{"apple": 1, "banana": 2, "cherry": 3}
for key, val := range m {
    fmt.Println(key, val)
}

In this example, the range keyword is used to iterate over the key-value pairs of the map m. The loop variable key represents the current key, and val represents the current value. The loop body prints both the key and value of each pair to the console.