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הפונקציה הראשית

שיעור 27 מתוך 29 בקורס פרויקט מחשבון באמצעות Python של Coddy.

אחרי שיש לנו את הפונקציה coordinate, כל מה שנותר הוא להוסיף את האפשרות לקבל קלט מהמשתמש ולקרוא ל־coordinate.

נסו לעשות זאת בתוך "הפונקציה הראשית" ב־Python (קראו עוד),

if __name__ == '__main__':
	...
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אתגר

קל

בקש קלט מהמשתמש והדפס את תוצאת החישוב.

נסו בעצמכם

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, 'all']
    for operators_group in operators_groups:
        i = 0
        while i < len(lst):
            if (not isinstance(lst[i], int) and not isinstance(lst[i], float)) if operators_group == 'all' else (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):
    try:
        pre_parse(s)
        parsed_s = parse(s)
        return eval(parsed_s)
    except Exception as e:
        return 'Error: ' + str(e)

כל השיעורים ביחידה פרויקט מחשבון באמצעות Python

תרגלו בעצמכם: קומפיילר Python אונליין