c++ find index of element in array

Code Example:

#include <iostream>

int findIndex(int arr[], int size, int target) {
    for (int i = 0; i < size; i++) {
        if (arr[i] == target) {
            return i;
        }
    }
    return -1;
}

int main() {
    int arr[] = {4, 7, 2, 8, 5};
    int target = 2;
    int size = sizeof(arr) / sizeof(arr[0]);
    int index = findIndex(arr, size, target);
    if (index != -1) {
        std::cout << "Element found at index: " << index << std::endl;
    } else {
        std::cout << "Element not found in the array" << std::endl;
    }
    return 0;
}

Explanation:

• Include the necessary header file:

• #include <iostream> - This line includes the input/output stream library which provides functionality for input and output through streams, such as std::cout and std::cin.

• Define the function to find the index of the element in the array:

• int findIndex(int arr[], int size, int target) - This function takes an array, its size, and the target element as parameters and returns the index of the target element in the array.

• Iterate through the array:

• for (int i = 0; i < size; i++) - This loop iterates through the elements of the array using the index variable i.

• Check for the target element:

• if (arr[i] == target) - This condition checks if the current element in the array is equal to the target element.

• Return the index if the element is found:

• return i; - If the target element is found, the function returns the index at which the element is located in the array.

• Return -1 if the element is not found:

• return -1; - If the loop completes without finding the target element, the function returns -1 to indicate that the element is not present in the array.

• Main function to test the findIndex function:

• int main() - This is the entry point of the program where the findIndex function is tested.

• Create an array and define the target element:

• int arr[] = {4, 7, 2, 8, 5}; - An array named arr is created with some elements.

• int target = 2; - The target element to be searched for is defined as 2.

• Calculate the size of the array:

• int size = sizeof(arr) / sizeof(arr[0]); - The size of the array is calculated using the sizeof operator.

• Call the findIndex function and display the result:

• int index = findIndex(arr, size, target); - The findIndex function is called with the array, its size, and the target element.
• if (index != -1) - If the returned index is not -1 (indicating the element was found), a message displaying the index is printed.

• else - If the index is -1, a message indicating that the element was not found is printed.

• Return 0 to indicate successful completion of the program.