Python之字符串计算（计算器）
import re
expression = '-1-2*((60+2*(-3-40.0+42425/5)*(9-2*5/3+357/553/3*99/4*2998+10*568/14))-(-4*3)/(16-3*2))+56+(56-45)'
question = eval(expression)
print(question)
def arithmetic(expression='1+1'):
# content = re.search('\(([\-\+\*\/]*\d+\.?\d*)+\)', expression) # (-3-40.0/5)
content = re.search('\(([-+*/]*\d+\.?\d*)+\)', expression) # (-3-40.0/5)
print(111, content)
if content:
content = content.group()
content = content[1:-1]
print('content:', content)
replace_content = next_arithmetic(content)
expression = re.sub('\(([-+*/]*\d+\.?\d*)+\)', replace_content, expression, count=1)
print('next_expression:', expression)
else:
answer = next_arithmetic(expression)
return answer
return arithmetic(expression)
def next_arithmetic(content):
while True:
next_content_mul_div = re.search('\d+\.?\d*[*/][-+]?\d+\.?\d*', content) # 找出带有*/的式子
if next_content_mul_div: # 如果content含有带有*/的式子
next_content_mul_div = next_content_mul_div.group()
print('next_content_mul_div:', next_content_mul_div)
mul_div_content = mul_div(next_content_mul_div) # 计算出带有*/的式子
print('mul_div_content:', mul_div_content)
content = re.sub('\d+\.?\d*[*/][-+]?\d+\.?\d*', str(mul_div_content), content, count=1) # 把带有*/的式子计算出来后替换掉
print('content:', content)
continue
next_content_add_sub = re.search('-?\d+\.?\d*[-+][-+]?\d+\.?\d*', content) # 找出带有-+的式子
if next_content_add_sub: # 如果content含有带有+-的式子
next_content_add_sub = next_content_add_sub.group()
print('next_content_add_sub:', next_content_add_sub)
add_sub_content = add_sub(next_content_add_sub) # 计算出带有-+的式子
print('add_sub_content:', add_sub_content)
add_sub_content = str(add_sub_content)
content = re.sub('-?\d+\.?\d*[-+]-?\d+\.?\d*', str(add_sub_content), content, count=1) # 把带有-+的式子计算出来后替换掉
print('content:', content)
continue
else:
break
return content
def add_sub(content):
if '+' in content:
content = content.split('+')
print(content)
content = float(content[0]) + float(content[1])
return content
elif '-' in content:
content = content.split('-')
# 减法情况有多种
if content[0] == '-' and content[2] == '-':
# content = content.split('-')
print(content)
content = -float(content[1]) - float(content[-1])
return content
if content[0] == '-':
# content = content.split('-')
print(content)
content = -float(content[1]) - float(content[-1])
return content
if content[1] == '-' and content[2] == '-':
# content = content.split('-')
print(content)
content = -float(content[0]) + float(content[-1])
return content
if content[1] == '':
# content = content.split('-')
print(content)
content = float(content[0]) - float(content[2])
return content
if content[0] == '' and content[2] != '':
print(content)
content = -float(content[1]) - float(content[2])
return content
if content[0] == '' and content[2] == '':
print(content)
content = -float(content[1]) + float(content[3])
return content
else:
# content = content.split('-')
print(content)
content = float(content[0]) - float(content[1])
return content
def mul_div(content):
if '*' in content:
content = content.split('*')
print(content)
content = float(content[0]) * float(content[1])
return content
elif '/' in content:
content = content.split('/')
print(content)
content = float(content[0]) / float(content[1])
return content
# expression = '1-2*((60+2*(-3-40.0/5)*(9-2*5/3+7/3*99/4*2998+10*568/14))-(-4*3)/(16-3*2))'
expression = '-1-2*((60+2*(-3-40.0+42425/5)*(9-2*5/3+357/553/3*99/4*2998+10*568/14))-(-4*3)/(16-3*2))+56+(56-45)'
answer = arithmetic(expression)
print(answer)
