TheAlgorithms-C-Plus-Plus/search/interpolation_search.cpp

#include<iostream>

// function to search the value in an array using interpolation search
int search(int arr[], int value, int len) {
        int low = 0, high, mid;
        high = len-1;
        while (arr[low] <= value && arr[high] >= value) {
            mid = (low + ((value-arr[low])*(high-low)) / (arr[high]-arr[low]));
            if (arr[mid] > value)
                     high = mid-1;
            else if (arr[mid] < value)
                     low = mid+1;
            else
                     return mid;
            }
        if (arr[low] == value)
                return low;
        return 0;
}

int main() {
        int n, value, array[100], re;
        std::cout << "Enter the size of array(less than 100) : ";
        std::cin >> n;
        std::cout << "array in ascending (increasing) order : " << std::endl;
        for (int i=0; i < n; i++)
                std::cin >> array[i];
        std::cout << "Enter the value you want to search : ";
        std::cin >> value;
        re = search(array, value, n);
        if (re == 0)
                std::cout << "Entered value is not in the array" << std::endl;
        else
                std::cout << "The value is at the position " << re << std::endl;
        return 0;
        }