"""
description : use python eval() function implement a simple calculator
functions can be used as follow：
----------------------------------------
+ : addition
- : minus
* : multiplication
/ : division
% : --> /100.0
e : math.e
pi : math.pi
sin : math.sin
cos : math.cos
^ : --> **
tan : math.tan
mod : --> %
sqrt: math.sqrt
rad: --> radius math.radians
round:
"""
import math
# 定義可以使用的函數及常量
functions=('e','pi','sin','cos','tan','sqrt','radians')
def calculate(expression):
expression=expression.lower()
# replace函數返回替換后的字符串
expression=expression.replace('%','/100.0')
expression=expression.replace('^','**')
expression=expression.replace('mod','%')
expression=expression.replace('rad','radians')
for i in functions:
if i in expression:
expression=expression.replace(i,'math.{}'.format(i))
try:
return (eval(expression))
except ZeroDivisionError:
print('zero can not be division')
except Exception as e:
print(e)
def main():
while True:
expression=input("input your expression here:")
if expression=='q':
break
else:
result=calculate(expression)
if result:
print(result)
if __name__=="__main__":
main()
