Arrays in C/C++?

An array is a sequential collection of elements of the same type. Arrays are used to store collections of data, but it is often more useful to think of arrays as collections of variables of the same type.

Instead of declaring individual variables, such as number0, number1, ... and number99, you can declare an array variable (such as numbers) and use numbers[0], numbers[1] and ..., numbers[99] to represent each variable. Specific elements in the array are accessed through indexing.

All arrays are composed of contiguous memory locations. The lowest address corresponds to the first element, and the highest address corresponds to the last element.

Declaring an array

Declaring an array requires specifying the type of elements and the number of required elements. An array is as follows -

type arrayName [ arraySize ];

Declare an array by specifying the size

This is called a one-dimensional array. arraySize must be an integer constant greater than zero, and the type can be any valid C data type. For example, to declare an array of 10 elements named balance and of type double, use the following statement -

double balance[10];

The elements of the array and how to access them?

A single piece of data in an array is an element of the array. You can use indexing to access elements of an array.

Suppose you declare an array tag as above. The first element is mark[0], the second element is mark[1], and so on. The array starts at index 0.

How to initialize an array in C programming?

Declare an array by specifying size and initializing elements

int mark[5] = {19, 10, 8, 17, 9};

Declaring an array by initializing elements

int mark[] = {19, 10, 8, 17, 9};

Here,

mark[0] is equal to 19; mark[1] is equal to 10; mark[2] is equal to 8; mark[3] is equal to 17; mark[4] is equal to 9

How to insert and print array elements ?

int mark[5] = {19, 10, 8, 17, 9}

// change 4th element to 9
mark[3] = 9;
// take input from the user and insert in third element
cin >> mark[2];
// take input from the user and insert in (i+1)th element
cin >> mark[i];
// print first element of the array
cout << mark[0];
// print ith element of the array
cout >> mark[i-1];

Example: C array

C program that uses an array to store and calculate the sum of 5 numbers entered by the user

Input

Enter 5 numbers:
3
4
5
4
2

Output

Sum = 18

Example

#include <iostream>
using namespace std;

int main() {
   int numbers[5], sum = 0;
   cout << "Enter 5 numbers: ";
   for (int i = 0; i < 5; ++i) {
      cin >> numbers[i];
      sum += numbers[i];
   }
   cout << "Sum = " << sum << endl;
   return 0;
}

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