In the main function, we initialize variables and arrays to store user input. We then loop through each element using a for loop and conditionally check if the current value meets the criteria with an if statement. If true, we perform operations such as addition or concatenation and store the result in a new array. Functions help modularize the code, making it reusable and maintainable. After processing, we return the final output and print the results. Error handling ensures the program runs smoothly, even when unexpected input is encountered. This approach is essential for writing efficient, clean, and bug-free code that performs as expected.