简单计算器的实现：
计算：1-2*((60-30+(-40.0/5)*(9-2*5/3+7/3*99/4*2998+10*568/14))-(-4*3)/(16-3*2))'
#!usr/bin/env python
# encoding: utf-
import re #乘除运算
def chengchu(formula):
while True:
s_formula = re.search('\d+\.?\d*[*/][-]?\d+\.?\d*',formula)
if s_formula:
s_formula_list = re.split('[*/]',s_formula.group())
if '*' in s_formula.group():
s_sub = float(s_formula_list[]) * float(s_formula_list[])
formula = formula.replace(s_formula.group(),str(s_sub))
elif '/' in s_formula.group():
s_sub = float(s_formula_list[]) / float(s_formula_list[])
formula = formula.replace(s_formula.group(),str(s_sub))
else:
print(s_formula_list,formula)
res = jiajian(formula)
return res #加减运算
def jiajian(formula2):
if '+-' in formula2 or '++' in formula2 or '-+' in formula2 or '--' in formula2:
formula2 = formula2.replace('+-', '-')
formula2 = formula2.replace('++', '+')
formula2 = formula2.replace('-+', '-')
formula2 = formula2.replace('--', '+')
while True:
s_f = re.search('\d+\.?\d*[+-]\d+\.?\d*',formula2)
if s_f:
s_f_list = re.split('[+-]',s_f.group())
print(s_f_list)
if '-' in s_f.group():
s_f_sub = float(s_f_list[]) - float(s_f_list[])
formula2 = formula2.replace(s_f.group(),str(s_f_sub))
elif '+'in s_f.group():
s_f_sub = float(s_f_list[]) + float(s_f_list[])
formula2 = formula2.replace(s_f.group(), str(s_f_sub))
continue
else:
print(formula2)
return formula2 #开始运算
def calc(arg):
while True:
m = re.search("\([^()]+\)",arg)
if m:
formula = m.group().strip('()')
print(formula)
m_result = chengchu(formula)
arg = arg.replace(m.group(),str(m_result))
continue
else:
print(arg)
su = chengchu(arg)
print(su)
break if __name__ == "__main__":
a = '1-2*((60-30+(-40.0/5)*(9-2*5/3+7/3*99/4*2998+10*568/14))-(-4*3)/(16-3*2))'
# a = '1-2*-1388338.2476190478'
calc(a)