How to Find Largest Number in an Array in C++?

In C++, arrays serve as containers for organizing a sequence of elements of the same data type in contiguous memory locations. These versatile structures can accommodate various data types including integers, characters, floats and more. This tutorial will explore an alternative method for identifying the maximum value within an array in C++.

Example:

Suppose we have an array of integers: {10, 5, 20, 8, 15}.

The largest number in this array is 20.

Find Largest Number in an Array in C++:

To find the largest number in an array in C++ is by utilizing the std::max_element() function. This function requires two arguments: the beginning iterator or pointer of the array and the ending iterator or pointer. It searches within this range to identify the maximum element.

Examples:

1. Using a Loop:

#include <iostream>

using namespace std;

int findLargest(int arr[], int n) {

    int maxElement = arr[0];

    for (int i = 1; i < n; ++i) {

        if (arr[i] > maxElement) {

            maxElement = arr[i];

        }

    }

    return maxElement;

}

int main() {

    int numbers[] = {10, 5, 20, 8, 15};

    int size = sizeof(numbers) / sizeof(numbers[0]);

    cout << "Largest number: " << findLargest(numbers, size) << endl;

    return 0;

}

Output : 

Largest number: 20

2. Using std::max_element():

#include <iostream>

#include <algorithm>

using namespace std;

int main() {

    int numbers[] = {10, 5, 20, 8, 15};

    int* maxElementPtr = max_element(numbers, numbers + 5);

    cout << "Largest number: " << *maxElementPtr << endl;

    return 0;

}

Output :

Largest number: 20

3. Using std::vector and std::max_element():

#include <iostream>

#include <vector>

#include <algorithm>

using namespace std;

int main() {

    vector<int> numbers = {10, 5, 20, 8, 15};

    auto maxElementIter = max_element(numbers.begin(), numbers.end());

    cout << "Largest number: " << *maxElementIter << endl;

    return 0;

}

Output :

Largest number: 20

4. Using C++11 Range-based for loop:

#include <iostream>

#include <vector>

using namespace std;

int main() {

    vector<int> numbers = {10, 5, 20, 8, 15};

    int maxElement = numbers[0];

    for (int num : numbers) {

        if (num > maxElement) {

            maxElement = num;

        }

    }

    cout << "Largest number: " << maxElement << endl;

    return 0;

}

Output :

Largest number: 20