Python 计算变量的内容

我正在学习python，我遇到了一个问题

for i in input:
    operator = i.split()[0]
    number1 = i.split()[1]
    number2 = i.split()[2]
    equation = (number1 + ' ' +  operator + ' ' + number2)

此代码用于计算随机生成的输入，例如：

+9 16

这个要我打印9+16的结果

所以我编写了代码，将输入转换成一个方程，但我不知道如何告诉代码来计算它

有人能帮我吗？

您不需要循环：

a = input()
operator = a.split()[0]
number1 = a.split()[1]
number2 = a.split()[2]
equation = (number1 + ' ' +  operator + ' ' + number2)
print(equation)

---

你不需要一个循环就能得到整个句子。由于split（）用于按给定参数拆分字符串，因此只需输入即可。只需使用a=input（）

在你的情况下，你可以试试

print(eval(equation)) #ugly

---

表达式是一个前缀表达式，其中运算符是第一个，后跟操作数

+9 16

是一个简单的表达式，因为这里只有一个运算符，即

+

和两个操作数

9

和

16

def evaluate(num1, num2, operator):
    # returns the result after evaluating the expression
    if operator == '+': 
        return(num1 + num2) 

    elif operator == '-': 
        return(num1 - num2) 

    elif operator == '*': 
        return(num1 * num2) 

    elif operator == '/': 
        return(num1 / num2)


a = str(input())
# a = "+ 9 16"

temp = None
operator = ""

for i in a.split():
    # a.split() is a list
    if i.isdigit():
        # isdigit() returns true if i is a number
        if not temp:
            # this is our first operand
            temp = int(i) 
        else:
            # this is our second operand
            print(evaluate(temp, int(i), operator))
    else:
        # this is our operator
        operator = i

为了计算更复杂的前缀表达式，我们通常使用堆栈。要了解有关计算复杂前缀表达式的详细信息，请参阅

def evaluate(num1, num2, operator):
    # returns the result after evaluating the expression
    if operator == '+': 
        return(num1 + num2) 

    elif operator == '-': 
        return(num1 - num2) 

    elif operator == '*': 
        return(num1 * num2) 

    elif operator == '/': 
        return(num1 / num2)


a = str(input())
# a = "+ 9 16"

temp = None
operator = ""

for i in a.split():
    # a.split() is a list
    if i.isdigit():
        # isdigit() returns true if i is a number
        if not temp:
            # this is our first operand
            temp = int(i) 
        else:
            # this is our second operand
            print(evaluate(temp, int(i), operator))
    else:
        # this is our operator
        operator = i