Find elements of an array which are divisible by N using STL in C++

Given with an array and the task is to find the number which are divisible by N using standard template library in C++.

To solve this problem we are using the function count_if() present in C++ standard template library.

What is a count_if() function?

Syntax

count_if(LowerBound, UpperBound, function)

Description − This function returns the number of elements in an array that satisfies the given condition. It takes three parameters.

Lower Bound − It points to the first element of an array or any other sequence.
Upper Bound − It points to the last element of an array or any other sequence.
Function − It returns the Boolean value on the basis of the condition specified.

Example

Input-: array[] = {2, 4, 1, 5, 8, 9}
N = 4
Output-: Elements divisible by 4: 2
Input-: array[] = {1, 2, 3, 4, 5, 10}
N = 2
Output: Elements divisible by 2: 3

Approach used in the below program is as follows −

Input the integer values in an array of integer type.
Create the bool function to check whether the element of an array is divisible by the user input value N.
Call the function count_if() which takes the first and the last element and the function as the parameter.

Example

Live Demo

#include <bits/stdc++.h>
using namespace std;
int n;
//function to check if the element is divisible by n
bool check(int i) {
   if (i % n == 0)
      return true;
   else
      return false;
}
int main() {
   int arr[] = {2, 4, 1, 5, 8, 9};
   n = 4;
   int size = sizeof(arr) / sizeof(arr[0]);
   int temp = count_if(arr, arr + size, check);
   cout<<"Elements divisible by "<<n<< ": " <<temp;
   return 0;
}