Differences Between Lists and Arrays in Programming

By Indeed Editorial Team

Published April 8, 2022

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Programmers often utilize list and arrays when writing code. Both lists and arrays offer many useful functionalities when writing programs. Learning about the differences between list and arrays may help you continue to develop your knowledge of various programming languages. In this article, we discuss the definitions of a list and an array, describe the major differences and similarities between them and answer some common questions about them.

What is a list?

In programming, a list is an ordered arrangement of elements. You often use lists when you want to store a set of values, such as a set of records in a database. For example, you create a list of dialogue phrases you can then reference later in the code to create dynamic conversations between characters in a video game.

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What is an array?

An array is a group of objects, typically used to hold values that can vary in size. You often use arrays in data structures, especially where you frequently access collections. An array can contain different types of data such as strings, integers and booleans. Arrays can also contain lists. For example, an array may include a list of numbers, where each number is an instance of a class.

List vs. array

There are many fundamental differences between lists and arrays, and a few key similarities. Here is a list of ways in which lists and arrays differ, with a description of each:

Usage

Programmers use lists to store collections of data, such as the characters in a string and the values of an integer array. They frequently use lists as arguments for functions and control structures. In contrast, programmers use arrays to store values that vary in size or type, such as the sum of numbers in an array. Lists can contain only one type of element such as integers or strings, whereas an array may have elements that are different kinds of data such as an integer, string and boolean.

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Flow Control

Programs control the flow of execution by branching or looping. A list cannot branch or loop, while an array may do both. For example, you may have a code branch that executes different statements depending on the index of an array. Additionally, while the elements in an array are ordered, the code can only iterate over the elements of a list sequentially. For example, you may want to iterate through the first ten items of a list in order.

Precise number of values

Programmers use lists to store collections of objects where they know the total number of objects ahead of time. Programmers often use arrays to store collections of objects when they don't know the total number of items ahead of time. For example, you might want to store a collection of students in a class, so you can use a list because the number is finite and defined.

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Indexing

A programmer uses an index to access elements in a list or array element. This allows programmers to access specific elements in a list or array using arbitrary indices, such as accessing data from different parts of an application without affecting the overall logic. Additionally, list indices start at 1, whereas array indices start at 0.

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Memory allocation

Programmers allocate memory to hold lists and arrays. You allocate lists on the stack while you allocate arrays on the heap. This difference cause you to call them from storage differently when referencing them later in the code.

Insertion and deletion

The insertion and deletion function also differ with lists and arrays. Programmers can insert or remove items added at the end of a list, but not lists that are ordered sequentially. In contrast, programmers can insert or remove items in an array, regardless of where the item is located in the array. insert() and delete() methods can be used to modify list elements.

Scalability

Lists and arrays can differ in terms of scalability. In some cases, lists are not scalable because elements are always of the same type. Arrays can store different data types.

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Value types and value semantics

The kinds of values that you can store in a list type are determined by the element format, whereas for an array the elements are always values of a specific type. For example, if you have a string object and you wish to store it in an array, it may be a requirement to declare that variable as an array variable because it is a value type.

Frequently asked questions about lists and arrays

When learning about lists and arrays, there are many common questions that you may have. Here are some answers to frequently asked questions about lists and arrays:

Do all programming languages use lists and arrays?

Not all programming languages use lists and arrays. List and arrays are common in object-oriented programming languages. For example, Python and Java both use lists and arrays.

How do you declare a list or array?

To create a list you can insert your own elements between the brackets. For example, in some programming languages to create a list of strings you insert several strings between the "[" and "]". To create an array you can define the size of the element in brackets: "[size]" where size is an integer.

Are lists and arrays always immutable?

In some programming languages, you can declare an object as mutable, which means that you can modify the object. Some programming languages, such as Python and Java, have lists and arrays that are immutable. This means you cannot modify them once you generate them. Though, this is not the case with many other programming languages.

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