Check if All Numbers in Array are Less than a Number in C++

This tutorial will discuss about a unique way to check if all numbers in array are less than a number in C++.

To check if all the elements of an array are less than a given number, we need to iterate over all the elements of array and check each element one by one.

For that we can use a STL Algorithm std::all_of(), which accepts the start & end iterators of an array as first two arguments. As this 3rd argument it will accept a Lambda function

This lambda function accept one argument and returns true, if the given argument is less than specific number, otherwise returns false.

The std::all_of() function will apply the given Lambda function on all the elements of array, and returns true only if the Lambda function returns true for all the elements of the array. The syntax is as follows,

int arr[] = {8, 9, 6, 1, 2, 5, 10, 14};
int number = 20;

// Check if all numbers are less than a specific number
bool result = std::all_of(
                std::begin(arr),
                std::end(arr),
                [&](const int& elem) {
                    return elem < number;
                });

Here std::all_of() function function will return true, if all the numbers in the array are less than a specific number i.e. number 20.

Let’s see the complete example,

#include <iostream>
#include <algorithm>

int main()
{
    int arr[] = {8, 9, 6, 1, 2, 5, 10, 14};
    int number = 20;

    // Check if all numbers are less than a specific number
    bool result = std::all_of(
                    std::begin(arr),
                    std::end(arr),
                    [&](const int& elem) {
                        return elem < number;
                    });

    if(result)
    {
        std::cout << "Yes, all elements in the array are less than a specifc number \n";
    }
    else
    {
        std::cout << "No, all elements in the array are not less than a speciifc number" << std::endl;
    }
    return 0;
}

Output :

Yes, all elements in the array are less than a specifc number

Summary

Today we learned about a way to check if all numbers in array are less than a number in C++. Thanks.