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发修改好的上来：
#!/usr/bin/python
#-*- coding: utf_8 -*-
############################ file name: lcal.py #######################################
############################ function: ################################################
# 1. normal calculation, including add, subtract, multiple, divide
# 2. mathematical power calculation, square root calculation (want to realize extraction
# root calculation in future )
# 3. other calculation will be realized in future if i think of it
#
#######################################################################################
#
############################ version 0.9 ###############################################
import math
class Calculator:
# __init__ function will just convert the argument string to 2 numbers and 1 operator
u'''About lcal:
This programm can process +, -, *, /, %, **(power calculation, for example, 3 ** 2 = 9),
//2 (extraction square root calculation, for example 9 // 2, '2' is required)
the form of input should be just like 1 + 1, or 1+1, otherwise lcal will prompt an error
message.
关于lcal:
lcal可以进行加，减，乘，除，模，乘方，和开平方运算，对应运算符为+, -, *, /, %, **, //2。
输入的模式为 1 + 1或者1+1等，如果输入错误，会有错误提示。输入help，显示本段信息，输入version
显示版本信息，输入quit退出。
'''
def __init__ (self, string):
operator_tp = '*', '/', '%', '-', '+'# 创建一个包含所需运算符的tuple，减号和加号必须放后面，不然很麻烦，
operator = '' #用于存储运算符 #如果放开头，当出现计算 5 * - 3的情况，operator将会是减号“-”
oper_index = 0 #存储运算符所在的位置，即下标
num1 = 0 #左操作数
num2 = 0 #右操作数
s = string.strip() #去头尾空格
#print s, operator_tp
self.statu = True #用于判断输入是否有效，即是否可以正常转换成两个数字和运算符
for op in operator_tp:
if s.find(op, 1) != -1: 从下标1开始找，避免将 -123 + 456 的第一个符号当做运算符
operator = op
oper_index = s.find(op, 1)
break #一找到运算符，跳出循环， 避免将 123 - -456的第二个减号当做运算符
if operator == '-':
if s.find('+', 1, oper_index) != -1: #如果出现 123 + -456的情况， 上面操作会把减号当做运算符，致使左操作数变成123 +，无法转换浮点数
operator = '+' #所以这里检查是否存在这种情况，存在的话，重新设置运算符，和运算符下标
oper_index = s.find('+', 1)
if operator == '+':
if s.find('-', 1, oper_index) != -1: #原因同上
operator = '-'
oper_index = s.find('-', 1)
#print operator
if operator in operator_tp:
if (operator == '*' and s[oper_index+1] == '*') or \ #判断是否要进行乘方开方运算，是的话，重新设置运算符，运算符下标不用重设
(operator == '/' and s[oper_index+1] == '/'):
num1 = s[0 per_index].strip() #并获取左右操作数
num2 = s[oper_index+2:].strip()
operator = operator + s[oper_index+1]
else:
num1 = s[0per_index].strip() #获取左右操作数
num2 = s[oper_index+1:].strip()
num1_sign = num1[0] #以下判断左右操作数字串第一位是否是正负号
num2_sign = num2[0]
if num1_sign.isdigit(): #如果第一位是数字，操作数直接转换成数字，无法转换的话，报错
try:
num1 = float(num1)
except ValueError:
print 'Left operand is invalid.'
self.statu = False
elif num1_sign[0] == '+' or num1_sign[0] == '-': #如果第一位是正负号，
num1 = num1[1:].strip() #去掉正负号和空格
try:
if num1_sign[0] == '+': #正数的话，直接转
num1 = float(num1)
else:
num1 = 0 - float(num1) #负数的话，用0减
except ValueError:
print 'Left operand is invalid.'
self.statu = False #无法转换，设置statu为False
else:
print 'Left operand is invalid.'
self.statu = False
if num2_sign.isdigit(): #以下同num1
try:
num2 = float(num2)
except ValueError:
print 'Right operand is invalid'
self.statu = False
elif num2_sign[0] == '+' or num2_sign[0] == '-':
num2 = num2[1:].strip()
try:
if num2_sign[0] == '+':
num2 = float(num2)
else:
num2 = 0 - float(num2)
except ValueError:
print 'Right operand is invalid'
self.statu = False
else:
print 'Right operand is invalid.'
self.statu = False
self.leftoperand = num1
self.rightoperand = num2
self.op = operator
else:
self.statu = False
#print num1, self.op, num2, self.statu
def add (self):
if int(self.leftoperand + self.rightoperand) == (self.leftoperand + self.rightoperand):
return int(self.leftoperand + self.rightoperand)
else:
return self.leftoperand + self.rightoperand
def subtract (self):
if int(self.leftoperand - self.rightoperand) == (self.leftoperand - self.rightoperand):
return int(self.leftoperand - self.rightoperand)
else:
return self.leftoperand - self.rightoperand
def multiply (self):
if int(self.leftoperand * self.rightoperand) == (self.leftoperand * self.rightoperand):
return int(self.leftoperand * self.rightoperand)
else:
return self.leftoperand * self.rightoperand
def divide (self):
if self.rightoperand != 0:
if int(self.leftoperand / self.rightoperand) == (self.leftoperand / self.rightoperand):
return int(self.leftoperand / self.rightoperand)
else:
return self.leftoperand / self.rightoperand
else:
return "False! divisor must not be 0 !"
def mod (self):
int_left = int (self.leftoperand)
int_right = int (self.rightoperand)
if int_left != self.leftoperand or int_right != self.rightoperand:# 2 operands must be integers for mod operation
return " lease enter integers!"
else:
if self.rightoperand != 0:
return (int_left % int_right)
else:
return "False! divisor must not be 0 !"
def power (self):
if int(self.leftoperand ** self.rightoperand) == (self.leftoperand ** self.rightoperand):
return int(self.leftoperand ** self.rightoperand)
else:
return self.leftoperand ** self.rightoperand
def sqrt (self):
if self.leftoperand >= 0:
if int(math.sqrt(self.leftoperand)) == math.sqrt(self.leftoperand):
return int(math.sqrt(self.leftoperand))
else:
return math.sqrt(self.leftoperand)
else:
return "The leftoperand for sqrt calculation must be greater than or equal to 0"
expr = raw_input ("type 'help' for help, 'version' to show version, 'quit' to quit\n>>"
judge = True
version = u'''lcal Version: 0.9
'''
while judge:
if expr != 'quit':
cal = Calculator (expr)
if expr != 'help' and expr != 'version':
if cal.statu == True:
if cal.op == '+':
print '>>', cal.add()
elif cal.op == '-':
print '>>', cal.subtract()
elif cal.op == '*':
print '>>', cal.multiply()
elif cal.op == '/':
print '>>', cal.divide()
elif cal.op == '%':
print '>>', cal.mod()
elif cal.op == '**':
print '>>', cal.power()
else:
print '>>', cal.sqrt()
else:
print '>>Wrong input! please input again.'
elif expr == 'version':
print version
else:
print cal.__doc__
expr = raw_input (">>"
else:
judge = False
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发表于 2012-03-28 18:19
