刷题 -- python计算器练习题
#/usr/bin/env python3 #mail infaaf@126.comimportre,sys
symbos_map={'+-':'-','++':'+','-+':'-','--':'+'}
# -1-(-1)*-1 =-2 #过程 -1--1*-1 => -1-- -1=> -1+-1 => -1-1 => -2
# 找最内括号，数字后面无符号，去除括号
# 找最内括号，有表示式，先乘除，乘除 从数字开始匹配， 1*-1 1*1
# 乘除完成，从左到右，带符号匹配。-1+-1 不等于 -（1-1） ，需要处理-1-------1 情况（由于乘除时未处理符号）
def calc_element_3(v1,v2,symbol):
print("计算： %s,%s,%s"%(v1,v2,symbol))
'''带符号 + - * / '''
v1,v2=float(v1),float(v2)
if symbol=='+':return v1+v2
elif symbol =='-':return v1-v2
elif symbol == '*':return v1*v2
elif symbol =='/':return v1/v2
else:print(symbol);sys.exit()
def multi_divi(s):
''' s括号内表达式，用于处理乘除。找到1*-2，处理为-2 ，处理1次 '''
print("处理乘除： %s"%s)
re_seach_obj=re.search(r'(+)([*/])([+-])?(+)',s)
if re_seach_obj is not None:
s_match_str = re_seach_obj.group(0)# 1*-1
value1=re_seach_obj.group(1)
value2=re_seach_obj.group(4)
simblos=re_seach_obj.group(2)
simblo_ext=re_seach_obj.group(3)
ret=calc_element_3(value1,value2,simblos)
ret=simblo_ext+str(ret)
print(s_match_str,ret)
s=s.replace(s_match_str,ret)
return s
# res=multi_divi('-1-2*-2') # print(res)
def add_minu(s):
print("处理加减： %s"%s)
''' -1--1,1--1,-1+1,-1---1,-1---------1，用于从左往右处理加减，处理1次'''
if re.search(r'[*/]', s):
print("should do * / before + -: %s"%s)
sys.exit()
while re.search(r'[+\-*\\]{2,}',s): #-1-1 ,1+++++1 => -1-1 , 1+1
for symbos_key in symbos_map:
s=s.replace(symbos_key,symbos_map)
# print(s)
re_seach_obj = re.search(r'([+-]?+)([+-])(+)', s)
if re_seach_obj:
s_match_str = re_seach_obj.group(0)# 1*-1
value1=re_seach_obj.group(1)
value2=re_seach_obj.group(3)
simblos=re_seach_obj.group(2)
ret=calc_element_3(value1,value2,simblos)
# print(s_match_str,ret)
s=s.replace(s_match_str,str(ret))
# print(s)
return s
# res=add_minu('1.0+1.5++++1')
def handler_expression(expression):
print("进入表达式处理%s"%expression)
while re.search('[*/]',expression):
expression=multi_divi(expression)
while re.search('+[+-]++',expression):
expression=add_minu(expression)
return expression
# res=handler_expression('-1+---5*-2/-1++2+2+2') # print(res)
# a=handler_expression('1+2--5.0*-3.0')
# print(a)
def hadler_braces(s):
print(s)
flag=True
while flag:
re_obj=re.search('\([+\-*/0-9.]*\)',s)
if re_obj:
s_match_str=re_obj.group(0)
print("括号匹配： %s"%s_match_str)
if re.match('\([+\-]?(*)\)',s_match_str):
print("仅剩余单个值: %s"%s_match_str)
s_match_str_match=re.match('\(([+\-]?*)\)',s_match_str).group(1)
s = s.replace(s_match_str, s_match_str_match)
print(s)
else:
print("调用处理%s"%s_match_str)
s_match_str_str=re.search('\(([+\-*/0-9.]*)\)',s).group(1)
ret=handler_expression(s_match_str_str)
s = s.replace(s_match_str, str(ret))
print(s)
else:
flag=False
return s
# no_braces_result=hadler_braces('(-1+(2-5*(-1))*(2-5))')
# result=handler_expression(no_braces_result)
# print(result)
if __name__ == '__main__':
while True:
exp=input("输入表达式: ")
exp=re.sub('\s','',exp)
no_braces_result=hadler_braces(str(exp))
result=handler_expression(no_braces_result)
print(result)
页:
[1]