验证字典中是否存在键或值，可用于char并不能用于数字

问题描述

当我提供输入1或3时，为什么下面的程序什么都不返回.并且在c的情况下有效.

#!/usr/local/bin/python3

d = {'a':1, 'b':3, 8:'c'}

x = input()
if x in d.values():
        print('In a dictionary')

更新:如果我提供a或b，则密钥也相同.有用.对于8，它不返回任何值.

y = input()

if y in d:
        print('key in dictionary')

我应该怎么做?

解决方案

input()返回一个字符串.以下代码可能会有用.

d = {'a':1, 'b':3, 8:'c'}

x = input()
from string import digits
if x in digits:
    x = int(x)
if x in d.values():
    print('In a dictionary', x)


>>> 
c
In a dictionary c

>>> 
3
In a dictionary 3

类似地，要签入密钥，请执行以下操作:

d = {'a':1, 'b':3, 8:'c'}

x = input()
from string import digits
if x in digits:
    x = int(x)
if x in d.values():
    print('In a dictionary', x)

if x in d:
    print ("In keys!")

输出测试:

>>> 
1
In a dictionary 1
>>> 
a
In keys!

要将键和值转换为字符串，可以使用字典理解.

>>> d = {'a':1, 'b':3, 8:'c'}
>>> d = {str(x): str(d[x]) for x in d}
>>> d
{'8': 'c', 'a': '1', 'b': '3'}

Why is below program returns nothing when I provide input 1 or 3. And works in case of c.

#!/usr/local/bin/python3

d = {'a':1, 'b':3, 8:'c'}

x = input()
if x in d.values():
        print('In a dictionary')

UPDATE:Same for key also if I provide a or b. It works. For 8, it returns none.

y = input()

if y in d:
        print('key in dictionary')

What should I do for these?

解决方案

The input() returns a string. Following code might be useful.

d = {'a':1, 'b':3, 8:'c'}

x = input()
from string import digits
if x in digits:
    x = int(x)
if x in d.values():
    print('In a dictionary', x)


>>> 
c
In a dictionary c

>>> 
3
In a dictionary 3

Similarly, to check in keys, do:

d = {'a':1, 'b':3, 8:'c'}

x = input()
from string import digits
if x in digits:
    x = int(x)
if x in d.values():
    print('In a dictionary', x)

if x in d:
    print ("In keys!")

Output Test:

>>> 
1
In a dictionary 1
>>> 
a
In keys!

To convert the keys and values to strings, you can use a dictionary comprehension.

>>> d = {'a':1, 'b':3, 8:'c'}
>>> d = {str(x): str(d[x]) for x in d}
>>> d
{'8': 'c', 'a': '1', 'b': '3'}

这篇关于验证字典中是否存在键或值，可用于char并不能用于数字的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！