Why use modular code?
Modular code is vital for the longevity of a program. Consider the car example again; it would be inefficient and expensive for a person to have to buy a new car every time they need to change their brake pads. A program is not different. A program needs to be structured in such a way that if a defect is found, you or another developer can easily navigate to the block of code where the defect occurs.
Though the organized structure of a program is a very important concept in code modularization, it is not the only reason to modularize code. There are many other reasons why you would want to modularize your code. It could be for the sake of code reusability. In other words, when your function is properly written, you can use it in another project without having to modify it. This comes back to the patch mentality. If you’re making a quilt, a quality patch can be used in any type of quilt; it is just a matter of sewing or integrating it into the project...