def Calculation():
number_str=""
print "欢迎您使用光荣之路计算机"
while 1:
print "退出系统请按回车键"
operation=raw_input("请输入您的下一步操作： ")
if operation=="":
operation=raw_input("您确定要退出系统吗，确定请按数字'1'： ")
if operation=="1":
print "退出成功"
break
elif operation in ["+","-","*","/","//"]:
if len(number_str)==0:
number_str+=operation
else:
if number_str[-1] in ["+","-","*","/","//"]:
print "您已经连续输入两次计算符号，请您重新输入要计算的数字"
else:
number_str+=operation
elif operation.isdigit():
if len(number_str)==0:
number_str+=operation
else:
if number_str[-1].isdigit():
print "您已经连续输入两次计算符号，请您重新输入要计算的数字"
else:
number_str+=operation
elif operation=="=":
if number_str=="":
print "您要计算得内容为空，请输入内容"
elif number_str[-1] in ["+","-","*","/","//"]:
print "您要计算的内容最后内容为空，请您输入计算内容"
else:
try:
if number_str[0].isdigit():
print number_str+"计算结果为："+str(eval_r(number_str))
else:
print "0"+number_str+"计算结果为："+str(eval_r(number_str))
except Exception:
print number_str+"计算过程中出现错误:"+e.message