code refactor and Improvements

[Dhaxor]

I made some refactor to the code to help anybody that might want to contribute to it and also made some improvements to it.
Here are a list of things I did

• Use #pragma once instead of including header files multiple times. This will prevent issues with multiple inclusion and make the code more readable.

• Use more descriptive variable names. For example, instead of using i for the loop variable, use a more descriptive name like arg_index. This will make the code easier to understand.

• Added comments to the code to explain what each function does and why it is needed. This will make the code easier to understand and maintain.

• Add error checking to the calls to atof and atoi to make sure that the input is valid.