Question

我有一个生成数学表的代码，我觉得有可能减少，因为我有三个相同的代码重复，但每个if / elif语句只有略微不同的解决方案。

num=10
x=str(input("Enter Math Operation (+, -, *): "))
while (x != "+" and x != "-" and x != "*"):
    x=str(input("\tEnter Math Operation: "))
    if x=="+":
        for table in range(1,11):
            print(str(num),str(x),table,"=",num+table) 
    elif x=="-":
       for table in range(1,11):
            print(str(num),str(x),table,"=",num-table) 
    elif x=="*":
       for table in range(1,11):
            print(str(num),str(x),table,"=",num*table)

请告诉我如何压缩此代码。

Answer 1

您通常会这样做：

将操作符存储为变量
使用字典查找运算符
使用.format()代替将大量字符串拼凑在一起
如果参数已经是字符串

str()

以下是这样的：

import operator
x = 10
operators = {
    '+': operator.add,
    '-': operator.sub,
    '*': operator.mul,
}
while True:
    op_name = input('Enter Math Operation ({}): '.format(', '.join(operators)))
    op_func = operators.get(op_name)
    if op_func is not None:
        break
for y in range(1, 11):
    print('{} {} {} = {}'.format(x, op_name, y, op_func(x, y)))

Answer 2

您可以使用查找表来存储不同的功能

num=10
x=str(input("Enter Math Operation (+, -, *): "))
while (x != "+" and x != "-" and x != "*"):
    x=str(input("\tEnter Math Operation: "))
ops = {
    '+': lambda x, y: x+y,
    '-': lambda x, y: x-y,
    '*': lambda x, y: x*y}

fn = ops[x]
for table in range(1,11):
    print(str(num),str(x),table,"=",fn(num,table))

Answer 3

函数是python中的第一类对象。将正确的函数分配给变量，然后使用它。

num=10
x=str(input("Enter Math Operation (+, -, *): "))
# Read operation
while (x != "+" and x != "-" and x != "*"):
    x=str(input("\tEnter Math Operation: "))
# Select appropriate function
if x=="+":
    op = lambda x, y : x + y
elif x=="-":
    op = lambda x, y : x - y
elif x=="*":
    op = lambda x, y : x * y

# Use function
for table in range(1,11):
    val = op(num, table)
    print(str(num), str(x),table,"=", val)

如何在范围内缩小＆＃39; for x＆＃39;声明如果＆＃39; ＆＃39; elif的＆＃39;在＆＃39; while＆＃39;内的陈述声明

3 个答案: