Systematic debugging

syntax errors. "Using incorrect syntax"

when the code itself has "wrong grammer" or is spelled incorrectly. Most times, the code will not run at all. Usually the interpreter/IDE will catch this.

syntax error. While is not spelled correctly

whil x > 3:

syntax error. used assignment (=) instead of a relational operator (==)

if x = 2:

run-time error. there is no parameter when the function is called

def dosomething(x):
....
dosomething()

run-time errors

an error that only occurs when the program runs
Sometimes you can write a program that uses up too much memory
Sometimes you can write a program that makes too many nested
function calls

run-time error

answer = int(input('Enter a number: '))
(the user enters a float)

the code runs!

answer = int(float(input('Enter a number: ')))
(the user enters a float)

the code runs!

answer = int(float(input('Enter a number: ')))
(the user enters an integer)

run-time error

my_list = [3, 6, 1]
a = my_list[20]

run-time error

b = 0
a = 5
c = a / b

run-time error. This goes on forever and eventually uses too much memory

L = [1]
while True:
L += [1]

logic errors

a mistake in how the code works. Code "runs" but produces the wrong output.
examples:
forgetting to indent
misspelling a variable name
typing the wrong variable name

try-except statements

used to prevent run-time errors from occurring, especially when the run-time error is a result of the user inputting incorrect data

TypeError

trying to perform an operation on the wrong type of
variable (adding int to str)

IndexError

trying to access an element out of range of a list

ZeroDivisionError

error when trying to divide by zero

NameError

trying to access a variable that does not exist