def check_value(num):
try:
num = float(num)
return True, num
except ValueError:
print("invalid data")
return False,
def check_op(operator):
if operator in ['+', '-', '*', '/']:
return True
else:
return False
def calc(v1,v2,oper):
if v1[0] and v2[0] and oper:
if op == "+":
result = v1[1] + v2[1]
if op == "-":
result = v1[1] - v2[1]
if op == "*":
result = v1[1] * v2[1]
if op == "/":
if v2[1] == 0:
result = False
else:
result = v1[1] / v2[1]
print(result)
return result
else:
print("wrong expression")
return False
exp = input("please input expression with spaces : ")
ls = exp.split()
while len(ls) >= 3 and len(ls) % 2:
x = ls[0]
y = ls[2]
op =ls[1]
result = calc(check_value(x),check_value(y),check_op(op))
if result != False:
del ls[:2]
ls[0] = result
else:
break
