#include <iostream> #include <string> using namespace std; string middle(string str) { int length = str.length(); if(length % 2 == 0) { return str.substr(length / 2 -1, 2); } else { return str.substr(length/2, 2); } } int main() { string word, result; cout << "Enter the word: "; cin >> word; result = middle(word); cout << result << "\n"; return 0; }

This is a C++ program that takes a string input from the user and returns the middle character(s) of the string. If the length of the string is even, it returns the middle two characters. If the length of the string is odd, it returns the middle character and the character after it.

Here's a step-by-step explanation:

1. The middle function is defined. It takes a string as an argument and returns a string.

2. The length of the string is calculated using the length() function and stored in the length variable.

3. An if statement checks if the length of the string is even by using the modulus operator %. If the length is even, the substr function is used to return the middle two characters of the string. The substr function takes two arguments: the starting index and the number of characters to include in the substring. In this case, the starting index is length / 2 - 1 (the index of the first middle character) and the number of characters is 2.

4. If the length of the string is odd, the else block is executed. The substr function is used to return the middle character and the character after it. The starting index is length / 2.

5. In the main function, the user is prompted to enter a word. This word is stored in the word variable.

6. The middle function is called with word as the argument, and the result is stored in the result variable.

7. The result is printed to the console.

8. The program returns 0 and ends.