Essential Go Slices  Edit on GitHub      File Issue

Create a slice

Slices are the typical way Go programmers store lists of data.

To declare a slice variable use the []Type syntax.

var a []int

To declare and initialize a slice variable in one line use the []Type{values} syntax.

var a []int = []int{3, 1, 4, 1, 5, 9}

Another way to initialize a slice is with the make function. It takes three arguments: the Type of the slice (or [map][ch-732]), the length, and the capacity.

a := make([]int, 0, 5)

You can add elements to your new slice using append.

a = append(a, 5)

Check the number of elements in your slice using len.

length := len(a)

Check the capacity of your slice using cap. The capacity is the number of elements currently allocated to be in memory for the slice. You can always append to a slice at capacity as Go will automatically create a bigger slice for you.

capacity := cap(a)

You can access elements in a slice using typical indexing syntax.

a[0]  // Gets the first member of `a`

You can also use a for loop over slices with range. The first variable is the index in the specified array, and the second variable is the value for the index.

for index, value := range a {
    fmt.Printf("Index: %v Value: %v\n", index, value)  // Prints "Index: 0 Value: 5" (and continues until end of slice)
}
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