1 import re 2 3 def multifly_cha(s): 4 ret = float(s.split("*")[0]) * float(s.split("*")[1]) if "*" in s else float(s.split("/")[0]) / float(s.split("/")[1]) 5 return ret 6 7 def remove_cha(s): 8 if "*" not in s and "/" not in s: 9 return s 10 else: 11 k = re.search(r"-?[\d\.]+[*/]-?[\d\.]+",s).group() 12 s = s.replace(k,"+" + str(multifly_cha(k))) if re.findall(r"-",k) == 2 else s.replace(k, str(multifly_cha(k))) 13 return remove_cha(s) 14 15 def add_up(s): 16 l = re.findall("([\d\.]+|-|\+)", s) 17 if l[0] == "-": 18 l[0] = l[0] + l[1] 19 del l[1] 20 sum = float(l[0]) 21 for i in range(1,len(l),2): 22 if l[i] == "+" and l[i+1] != "-": 23 sum += float(l[i+1]) 24 elif l[i] == "+" and l[i + 1] == "-": 25 sum -= float(l[i + 2]) 26 elif l[i] == "-" and l[i + 1] == "-": 27 sum += float(l[i + 2]) 28 elif l[i] == "-" and l[i + 1] != "-": 29 sum -= float(l[i + 1]) 30 31 return sum 32 33 def basic_operation(s): 34 s = s.replace(' ','') 35 return add_up(remove_cha(s)) 36 37 def calculate_(expression): 38 if not re.search(r"\([^()]+\)",expression): 39 return basic_operation(expression) 40 k = re.search(r"\([^()]+\)",expression).group() 41 expression = expression.replace(k,str(basic_operation(k[1:len(k)-1]))) 42 return calculate_(expression) 43 44 s = '1 - 2 * ( (60-30 +(-40/5) * (9-2*5/3 + 7 /3*99/4*2998 +10 * 568/14 )) - (-4*3)/ (16-3*2) )' 45 print("the evals results is: {}\nthe calculate results is: {}".format(eval(s),calculate_(s)))
