简单的四则混合运算,加上小括号。
import re user_input=r'1 - 2 * ( (60-30 +(-40/5) * (9-2*5/3 + 7 /3*99/4*2998 +10 * 568/14 )) - (-4*3)/ (16-3*2) )' def reslut(in_str): #判断字符串内是否有括号 for i in in_str: if i=='(': return False return True def replace_str(in_str): #去空格 out_str = in_str.replace(" ", '') return out_str def is_operation(oper): #判断是否为计算符号 if oper == '+' or oper == '-' or oper == '*' or oper == '/': return True else: return False def my_list(in_str): #把数据存入列表中 list1=[] t='' #向list1添加数据 n='' for i in in_str: if in_str[0]=='-' and len(list1)==0 and t=='': t=t+i elif is_operation(i): if is_operation(n): t=t+i else: list1.append(t) list1.append(i) t='' else: t=t+i n=i list1.append(t) return list1 def calculator_one(in_list): if ('*'in in_list) or ('/'in in_list): i=0 out_list=in_list for item in in_list: if item=='*': a=float(in_list[i-1]) b=float(in_list[i+1]) out_list[i-1]=str(a*b) out_list[i]='' out_list[i+1] = '' break elif item=='/': a=float(in_list[i-1]) b=float(in_list[i+1]) if b==float(0): print("被除数不能为0") exit() out_list[i-1]=str(a/b) out_list[i]='' out_list[i+1] = '' break i+=1 new_list = [x for x in out_list if x != ''] return calculator_one(new_list) else: return in_list def calculator_two(in_list): if '+'in in_list or '-' in in_list: i=0 out_list=in_list for item in in_list: if item=='+': a=float(in_list[i-1]) b=float(in_list[i+1]) out_list[i-1]=str(a+b) out_list[i]='' out_list[i+1] = '' break elif item=='-': a=float(in_list[i-1]) b=float(in_list[i+1]) out_list[i-1]=str(a-b) out_list[i]='' out_list[i+1] = '' break i+=1 new_list = [x for x in out_list if x != ''] return calculator_two(new_list) else: return in_list def replace_brackets(in_str): #去括号 if reslut(in_str): n=my_list(in_str) n=calculator_one(n) n=calculator_two(n) return n[0] else: out_str=re.search(r'([^(,^)]*)',in_str) t=out_str.group() t = t.replace('(', '') t = t.replace(')', '') t=my_list(t) t=calculator_one(t) t=calculator_two(t) in_str=re.sub(r'([^(,^)]*)',t[0],in_str,1) return replace_brackets(in_str) # in_str.replace(out_str,t) b=replace_str(user_input) b=replace_brackets(b) print(b) print(eval(user_input))