Arrays in C++

Prateek Narang

Topics

Introduction
Array Operations
Searching, Sorting
Passing Arrays to Functions
Dynamic Arrays

Motivation & Need for Arrays

Store marks of 1000 students, and create a ranklist

s1 - 86

s2 - 92

s3 - 100

s4 - 76

...

Arrays

A C++ array is a collection of elements of the same type placed in contiguous memory locations
Creation
Input
Output
Update


int arr[1000];

Arrays Basic Operations

Create
Input
Output
Search

// Many ways to create the array	
int a[100];
    
int a[100] = {0};
    
int a[100] = {1,2,3};

int a[] = {1,2,3};
    
string fruits[4] = {"apple","mango","guava"}

Passing Array to Functions

// Let's Practice

Example - Write a function to print the array.

More Operations

Insert in an Array
Delete in an Array

// Many ways to create the array	
int a[100];
    
int a[100] = {0};
    
int a[100] = {1,2,3};

int a[] = {1,2,3};
    
string fruits[4] = {"apple","mango","guava"}

Searching means to find the index of element in a given array. The most common way of searching is Linear Search, in which we go through every element of the array and compare with the given element.

Searching in Arrays

int arr[] = {1,2,0,10,11,9,8,8,7};
int key = 9;

// Let's Build Linear Search Algorithm

Sorting means to arrange elements in a specific order, either increasing or decreasing based upon element's value.

Sorting in Arrays

//Unsorted Array
a = {10,12,5,4,1,3,2};


//Sorted Array in Increasing Order
a = {1,2,3,4,5,10,12}

//Sorted Array in Decreasing Order
a = {12,10,5,4,3,2,1}

Integer Arrays

Float Arrays

Character Arrays

Boolean Arrays

Arrays with other Datatypes

int x = 10, y=20;

// Declaring a Pointer
int * xPtr = &x; // a pointer to an integer value 

// Setting to NULL
xPtr = 0;
int *p = 0;
int *q = NULL;

Reference Variables

A reference variable is an alias, that is, another name for an already existing variable.

Once a reference is initialised with a variable, either the variable name or the reference name may be used to refer to the variable.

Reference Variable

int x = 10;

int &y = x; // Here y is a reference variable

Problems!

1. Pass by Value

2. Pass by Reference

- using pointers

- using reference variables