1.首先表达式的空格。
2.循环计算最内层带括号的表达式(提取运算符出现的顺序,然后计算)
3.计算最外层的表达式输出。
刚接触python,代码不够严谨,仅实现功能。不知道如何在函数中使用运算符变量做运算(使用的时候是字符串形式),希望知道的朋友告诉我,互相学习一下。
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
import re,math def qcysf(s): while re.findall('+-|++|--|-+',s): s = s.replace('+-','-') s = s.replace('++','+') s = s.replace('--','+') s = s.replace('-+','-') return s def yunsuan(a1): temp1 = re.sub('d|.|+|-| ','',a1) # print(temp1) # print(a1) for i in temp1: if i == "*": b = re.search('(-?d+.?d**-?d+.?d*)', a1).group() # print(b) temp2 = round(float(b.split('*')[0]) * float(b.split('*')[1]),10) temp2 = '+' + str(temp2) a1 = a1.replace(b, temp2,1) # print(a1) else: b = re.search('(-?d+.?d*/-?d+.?d*)', a1).group() # print(b) temp2 = round(float(b.split('/')[0]) / float(b.split('/')[1]),10) temp2 = '+' + str(temp2) a1 = a1.replace(b, temp2,1) # print(a1) a1 = qcysf(a1) # print(a1) a2 = a1.lstrip('-') temp3 = re.sub('d|.| ', '', a2) for i in temp3: if i == "+": b = re.search('(-?d+.?d*+d+.?d*)', a1).group() temp2 = round(float(b.split('+')[0]) + float(b.split('+')[1]),10) a1 = a1.replace(b, str(temp2),1) # print(a1) else: b = re.search('(d+.?d*-d+.?d*)', a1).group() temp2 = round(float(b.split('-')[0]) - float(b.split('-')[1]),10) a1 = a1.replace(b, str(temp2),1) # print(a1) return a1 if __name__ == "__main__": a = input('请输入你要计算的内容:') a = a.replace(' ','') # print(a) if re.findall('[a-zA-Z]]',a): print('你输入的内容不合法') else: while re.search("([^()]+)", a): b = re.search("([^()]+)", a).group() # b = qcysf(b) # print(a) # print(b) b1 = re.sub('(|)','',b) # print(a) temp = yunsuan(b1) a = a.replace(b, str(temp)) # print('这是倒数第二个',a) a = qcysf(a) a = yunsuan(a) print(a)
请输入你要计算的内容:1 - 2 * ( (60-30 +(-40/5) * (9-2*5/3 + 7 /3*99/4*2998 +10 * 568/14 )) - (-4*3)/ (16-3*2) )
2776672.6951997215