Strings, ints, and operators in Python

问题

How can I use an arithmetic operator (input by the user as a string) in an operation? I can print the operation itself, but I want to print the solution!

Here's my clumsy attempt:

# Initialise variables

x = 2
y = 3

# Prompt the user for an arithmetic operator

operator = input("Please enter  *,  /,  +,  or  - : ")

# Calculate the operation

result = (str(x) + operator + str(y))

# Display the result

print(result)

回答1:

Use the operator module, which has functions that perform the same operations as your arithmetic operations.

import operator
ops = {'*': operator.mul, '/': operator.div, '+': operator.add, '-': operator.sub}

op = input("Please enter  *,  /,  +,  or  - : ")
result = ops[op](x, y)

来源：https://stackoverflow.com/questions/15521281/strings-ints-and-operators-in-python