def check_value(opand):
try:
if type(float(opand)) == float:
return float(opand)
except:
print('wrong input data')
return None
exp = input("Please input expression with spaces in between operand and operator")
exp = exp.split()
success = False
while len(exp) >= 3 and len(exp) % 2:
x = exp[0]; y = exp[2]; op =exp[1]
x = check_value(x); y = check_value(y)
if x != None and y !=None:
if op in ['+', '-', '*', '/']:
if op == '+':
result = x + y
if op == '-':
result = x - y
if op == '*':
result = x * y
if op == '/':
try:
result = x / y
except:
print("second value can not be zero")
result = None
break
del exp[:2]
exp[0] = result
success = True
else:
print("wrong operator")
break
else:
break
else:
if success:
print(f"The calculated result is: {exp[0]}")
else:
print("wrong expression")
