Golang Append Function

Introduction

The golang append method helps us add any number of items in the slice or at the end of the slice. This append function is built-in and adds an element at the end of the slice. The following are the conditions for using the append function:

• The underlying array is reused if there is enough capacity
• If there is not enough capacity, then a new underlying array is allocated along with copying over the data

The golang append method returns the updated slice and therefore the result needs to be stored in a variable that is holding the slice.

Syntax

The syntax of the golang append function is as follows:

Here, in this syntax, the function takes the parameter as an s slice, and x, T is a variable that takes a variable number of arguments for the following x parameter. These types of functions are called variadic functions. Parameters and return value The following parameters are accepted by the Append in Golang:

• A slice of Go language but a valid one
• Elements that are to be appended after a slice given should be of the same type as that of the slice.

Append Example

Behaviour of capacity of the slice

The slice can give five pieces of information when the data is appended:

• The length by using the method len(slice)
• The capacity by using the method cap(slice)
• The elements inside the slice by using fmt.Sprintf("%v", slice)
• The memory or the location where the values of the elements are stored by using fmt.Sprintf("%p", slice)
• The type of the elements stored in the slice by using fmt.Sprintf("%T", slice)

Let's look at the example and understand how to Append in Golang:

Output:

Append one Slice to Another

The code given below demonstrates how to use the golang append function to append one slice to another in Golang

Output:

Run Code

Explanation: In this example, the first slice is created and printed after which an element is appended to the first slice and is printed. In example 2, however, two elements are appended in the same slice that is created at the start. In example 3, a slice is created and the entire slice is appended in the first slice as shown in the code.

Append the string to a byte slice

We can also append a string to a byte slice, let's look at the code snippet given below to learn how to append a string to a byte slice

Output:

Run Code

Explanation: It is similar to that of normal append, instead in this case, we just had to unpack the string to byte. The resulting byte is displayed at the output.