变量中的计算总和

Sum of calculation in a variable

我对如何在变量中进行计算感到困惑。目前我的代码将打印(例如):(1,'+',2)。但我需要答案的实际总和。我的代码:

def calc(num1,op,num2):
    sum = num1,op,num2
    print(sum)

num1 = int(input("First number:"))
op = input("Operator:")
num2 = int(input("Second number:"))

calc(num1,op,num2)

这可以帮助你.....

def calc(x=0, y=0, z=0):
    expression = raw_input('Enter an expression: ')

    return eval(expression, None, locals())

示例:

>>> calc()
Enter an expression: 8 + 5 - 7
6