What you might want is to put the input taking code into the while loop:
while True:
num1 = float(raw_input("enter a number: ")) # type: float
operation = str(raw_input("enter a operation: "))
num2 = float(raw_input("enter a number: ")) # type: float
if operation == "+":
print (num1 + num2)
elif operation == "-":
print (num1 - num2)
elif operation == "*":
print (num1 * num2)
elif operation == "/":
print (num1 / num2)
else:
print("Error Error")
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…