How to Find the Index of an Element in an Array in C++?
In C++, an array is a data structure used to store similar types of data in contiguous memory locations. In this article, we will learn how to find the index of an element in an array in C++.
Example:
Input:
myArray = {1, 2, 3, 4, 5};
target = 3
Output:
The element 3 is at index: 2
Finding the Index of an Element in C++ Array
To find the index of an element in an array in C++, we can use the find() function that performs the linear search in the given range and returns the pointer to the matching element. We can then find the index by subtracting the pointer to the beginning of the array from this pointer.
C++ Program to Find the Index of an Element in an Array
The following program illustrates how we can find the index of an element in an array in C++.
// C++ Program to illustrate how to find the index of an
// element in an array
#include <iostream>
#include <algorithm>
using namespace std;
int main()
{
// Initializing an array
int myArray[] = { 1, 2, 3, 4, 5 };
int n = sizeof(myArray) / sizeof(myArray[0]);
// element to find
int target = 3;
// using find() to get the pointer to the first
// occurence
int* targetPtr = find(&myArray[0], myArray + n, target);
// getting index from pointer
int targetIndex = targetPtr - myArray;
// checking if the element found or not
if (targetIndex > 4)
cout << "Element not Found!\n";
else
cout << "Element Found at Index: " << targetIndex;
return 0;
}
Output
Element Found at Index: 2
Time Complexity: O(n), here n is the size of the array.
Auxiliary Space: O(1)