a=flat(input("输入第一个数:")
ch=
b=float(input("输入第二个数:"))
if ch== "+":
print(a,ch,b,"=",a+b)
elifch=="-":
print(a,ch,b,"=",a-b)
elif ch == *":
print(a,ch,b,"=",a*b)
elif ch == "/":
if
print(a,ch,b,"=",a/b)
else:
print("除数不能为0")
else:
print("运算符不正确")