def check_num(num):
try:
return float(num)
except ValueError:
print("input error" + str(num))
exit()
def check_op(operator):
if operator in ["+","-","*","/"]:
return True
else:
print("Wrong operator")
return False
#try:
#a = float(a)
#b = float(b)
# if op in ["+","-","*","/"]:
#print("op is right")
def calc(a,b,op):
a = check_num(a)
b = check_num(b)
print(a,b)
if check_op(op):
if op == '+':
result = a + b
if op == '-':
result = a - b
if op == '*':
result = a * b
if op == '/':
if b == 0:
print("** b can not be zero **")
else :
result = a/b
return result
result = 0
#else:
#print("wrong operator")
#except:
#print("Error")
#except ZeroDivisionError :
#print("b can't be zero")
# print("data type error")
#exp = '1+1'
exp = '1 + 1'
exp = exp.split()
print(exp)
#a = -2
#b = 9
#op = '/'
while (len(exp) >=3 and len(exp)%2):
a = exp[0]
b = exp[2]
op = exp[1]
result = calc(a,b,op)
del exp[:2]
print(exp)
exp[0] = result
print ("expression result is:" + str(result))
