It is important to have good programming practices so that you can, for the most part, avoid having to debug your programs.

When writing a program:

1. Understand the Problem
- Decide clearly on what you are trying to accomplish. It is not necessary to know exactly how to accomplish it, but an understanding of what output should be produced for some input will allow you to test the results of your program.

2. Work in Small Parts
- Rather than sitting down and writing a whole program at once, work in small, modular chunks and ensure that it works at each step. Writing out large programs at once without testing in between can lead to debugging nightmares where it is very difficult to pinpoint where an error is occurring.

Remember the mantra: "Get something working and keep improving it".

Rutgers University

- Look for the line number in the error message to find where the interpreter believes the error is coming from. Trace backwards if error doesn't stem from that line
- Understand the different types of errors (Syntax, Runtime, Semantic) 
- Use print statements to check the values of variables and if a block of code is being run, especially when your code has if-statements or loops
- Debug code in blocks as you go. This will make it easier to find more subtle semantic issues instead of having to look through your entire program when debugging at the end
-Usage of Break Points can be very useful if your IDE allows for it. This way you can run the program up to the break point and step through the code step by step checking the value of variables and comparing it to what you expect it to be. If there is a miss-match then you can trace it back to the line where the program deviated from your intended functionality. 

-When dealing with large amounts of data, use mocking to test your code as you build bigger projects. Mocking is the action of running smaller, more palpable data sets through code to more easily see errors in code designed for larger amounts of data. 

General Tips for Debugging

https://runestone.academy/runestone/books/published/fopp/index.html

Runestone: Foundations of Python Programming

```python
##Say that I am creating a function meant to 
##shift every character in a text document up 
##one character, ie. 'b' would turn to 'c'.
text=moby_dick.txt
shift=1
def shift_text(text, shift):
  shifted=''
  for ch in text:
      shifted+=shifted.join(chr(97+((ord(ch)-96+shift)%26)))
    else:
      shifted+=ch
  return shifted
##For some reason, this function doesn't work 
##when I run it. To debug this, I decide to just 
##manipulate the string 'How are you?'. That 
##would look like this:
text='How are you?'
shift=1
def shift_text(text, shift):
  shifted=''
  for ch in text:
      shifted+=shifted.join(chr(97+((ord(ch)-96+shift)%26)))
    else:
      shifted+=ch
  return shifted
##This lets me see that '?' characters are being 
##changed, which is not something that I want. 
##Thus, I now know I need to exclude non-letter
##characters:
def shift_text(text, shift):
  shifted=''
  for ch in text:
    if 'a'<=ch and 'z'>=ch:
      shifted+=shifted.join(chr(97+((ord(ch)-96+shift)%26)))
    else:
      shifted+=ch
  return shifted
##Now my code works, through the use of mocking. 

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