Learn X By Example
Learn X By Example

    Go by Example: Arrays

    Go by Example : Arrays

    In Go, an array is a numbered sequence of elements of a specific length. In typical Go code, slices are much more common; arrays are useful in some special scenarios.

    package main
    import "fmt"
    func main() {

    Here we create an array a that will hold exactly 5 int s. The type of elements and length are both part of the array’s type. By default an array is zero-valued, which for int s means 0 s.

        var a [5]int
    fmt.Println("emp:", a)

    We can set a value at an index using the array[index] = value syntax, and get a value with array[index] .

        a[4] = 100
    fmt.Println("set:", a)
    fmt.Println("get:", a[4])

    The builtin len returns the length of an array.

        fmt.Println("len:", len(a))

    Use this syntax to declare and initialize an array in one line.

        b := [5]int{1, 2, 3, 4, 5}
    fmt.Println("dcl:", b)

    You can also have the compiler count the number of elements for you with ...

        b = [...]int{1, 2, 3, 4, 5}
    fmt.Println("dcl:", b)

    If you specify the index with : , the elements in between will be zeroed.

        b = [...]int{100, 3: 400, 500}
    fmt.Println("idx:", b)

    Array types are one-dimensional, but you can compose types to build multi-dimensional data structures.

        var twoD [2][3]int
    for i := 0; i < 2; i++ {
        for j := 0; j < 3; j++ {
            twoD[i][j] = i + j
        }
    }
    fmt.Println("2d: ", twoD)

    You can create and initialize multi-dimensional arrays at once too.

        twoD = [2][3]int{
        {1, 2, 3},
        {1, 2, 3},
    }
    fmt.Println("2d: ", twoD)
}

    Note that arrays appear in the form [v1 v2 v3 ...] when printed with fmt.Println .

    $ go run arrays.go
emp: [0 0 0 0 0]
set: [0 0 0 0 100]
get: 100
len: 5
dcl: [1 2 3 4 5]
dcl: [1 2 3 4 5]
idx: [100 0 0 400 500]
2d:  [[0 1 2] [1 2 3]]
2d:  [[1 2 3] [1 2 3]]

    Next example: Slices .

    Next
    Go by Example: Atomic Counters