In programming, one of the frequently arising problem is to handle numerous data of same type.
Consider this situation, you are taking a survey of 100 people and you have to store their age. To solve this problem in C++, you can create an integer array having 100 elements.
An array is a collection of data that holds fixed number of values of same type. For example:
int age[100];
Here, the age array can hold maximum of 100 elements of integer type.
The size and type of arrays cannot be changed after its declaration.
dataType arrayName[arraySize];
For example,
float mark[5];
Here, we declared an array, mark, of floating-point type and size 5. Meaning, it can hold 5 floating-point values.
You can access elements of an array by using indices.
Suppose you declared an array mark as above. The first element is mark[0], second element is mark[1] and so on.
(n-1)
index is used. In this example, mark[4] is the last element.mark[0]
is 2120d. Then, the next address, a[1]
, will be 2124d, address of a[2]
will be 2128d and so on. It's because the size of float is 4 bytes.It's possible to initialize an array during declaration. For example,
int mark[5] = {19, 10, 8, 17, 9};
Another method to initialize array during declaration:
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
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];
C++ program to store and calculate the sum of 5 numbers entered by the user using arrays.
#include <iostream>
using namespace std;
int main()
{
int numbers[5], sum = 0;
cout << "Enter 5 numbers: ";
// Storing 5 number entered by user in an array
// Finding the sum of numbers entered
for (int i = 0; i < 5; ++i)
{
cin >> numbers[i];
sum += numbers[i];
}
cout << "Sum = " << sum << endl;
return 0;
}
Output
Enter 5 numbers: 3 4 5 4 2 Sum = 18
Suppose you declared an array of 10 elements. Let's say,
int testArray[10];
You can use the array members from testArray[0]
to testArray[9]
.
If you try to access array elements outside of its bound, let's say testArray[14]
, the compiler may not show any error. However, this may cause unexpected output (undefined behavior).
Before going further, checkout these C++ array articles:
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