Errors
Lesson 26 of 29 in Coddy's Calculator project using Python course.
We have been handling all the errors in each one of the functions, now let's use them.
Challenge
EasyAdd to coordinate the option to return error message with 'Error: ' in the start.
Try it yourself
def calc(op, n1, n2=None):
if not isinstance(n1, int) and not isinstance(n1, float):
raise Exception('Invalid number "' + str(n1) + '"')
if n2 is None:
if op == '+' or op == 'add':
return n1
if op == '-' or op == 'sub':
return -n1
raise Exception('Invalid operator "' + op + '"')
if not isinstance(n2, int) and not isinstance(n2, float):
raise Exception('Invalid number "' + str(n2) + '"')
if op == '+' or op == 'add':
return n1 + n2
if op == '-' or op == 'sub':
return n1 - n2
if op == '*' or op == 'mul':
return n1 * n2
if op == '/' or op == 'div':
if n2 == 0:
raise Exception("Division by zero")
return n1 / n2
if op == '%' or op == 'mod':
if n2 == 0:
raise Exception("Division by zero")
return n1 % n2
if op == '^' or op == 'pow':
return n1 ** n2
raise Exception('Invalid operator "' + op + '"')
def eval(lst):
if not isinstance(lst, list):
raise Exception('Failed to evaluate "' + str(lst) + '"')
if len(lst) == 2:
op = lst[0]
n = lst[1]
if not isinstance(n, list):
return calc(op, n)
if isinstance(n, list):
n = eval(n)
return calc(op, n)
elif len(lst) == 3:
op = lst[0]
n1 = lst[1]
n2 = lst[2]
if not isinstance(n1, list) and not isinstance(n2, list):
return calc(op, n1, n2)
if isinstance(n1, list):
n1 = eval(n1)
if isinstance(n2, list):
n2 = eval(n2)
return calc(op, n1, n2)
else:
raise Exception('Failed to evaluate "' + str(lst) + '"')
LEVEL_TWO_OPERATORS = ['+', '-', 'add', 'sub']
LEVEL_ONE_OPERATORS = ['*', '/', '%', 'mul', 'div', 'mod']
FUNCTIONS_OPERATORS = ['^', 'pow']
def struct(lst):
if not isinstance(lst, list) or len(lst) <= 1:
raise Exception('Failed to structure "' + str(lst) + '"')
if len(lst) == 2:
return lst
lst_cpy = lst
operators_groups = [FUNCTIONS_OPERATORS, LEVEL_ONE_OPERATORS, LEVEL_TWO_OPERATORS]
for operators_group in operators_groups:
i = 0
while i < len(lst):
if lst[i] in operators_group:
if len(lst) - 1 == i:
raise Exception('Failed to structure "' + str(lst_cpy) + '"')
if len(lst) == 3:
return [lst[i], lst[i - 1], lst[i + 1]]
temp = lst[:i - 1]
temp.append([lst[i], lst[i - 1], lst[i + 1]])
temp += lst[i + 2:]
lst = temp
else:
i += 1
return lst
NUMBERS = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9']
PARENTHESIS = ['(', ')']
def get_next(s, i):
if i >= len(s):
raise Exception('End of string')
res = ''
if s[i] in NUMBERS or s[i] == '.':
is_float = False
while i < len(s) and (s[i] in NUMBERS or s[i] == '.'):
res += s[i]
if s[i] == '.':
is_float = True
i += 1
if is_float:
return float(res)
return int(res)
else:
while i < len(s) and not (s[i] in NUMBERS or s[i] == '.' or s[i] in PARENTHESIS):
res += s[i]
i += 1
return res
def parse(s):
s = s.replace(' ', '')
i = 0
res = []
while i < len(s):
if s[i] in PARENTHESIS:
if s[i] == ')':
return struct(res), i
elif s[i] == '(':
temp = parse(s[i + 1:])
i += temp[1] + 2
res.append(temp[0])
else:
temp = get_next(s, i)
res.append(temp)
i += len(str(temp))
return struct(res)
def pre_parse(s):
if s.count('(') != s.count(')'):
raise Exception('Not matching parenthesis')
def coordinate(s):
parsed_s = parse(s)
return eval(parsed_s)