检查条件语句中的数据类型

Question

I want to print a character from a string if it is an integer.

This is a simplified and specific sample code which I wrote after zeroing-in on the problem in a code I was writing for a Kata in Codewars. While the Kata is not relevant here, I can't seem to figure out how to use data type in a conditional statement (something like if type(char) == int ).

string = "th3is i1s anot4her ra2ndom strin5g"
for word in string:
    for char in word:
        if type(char) == int:
            print(char)

Answer 1

1. You never split your string into words, so the outer loop makes no sense.
2. You are iterating over characters, which are length 1 strings. The type of a length 1 string is never equal to int .
3. You can use the str.isdigit method.

Rewritten code with a single loop:

for c in string:
    if c.isdigit():
        print(c)

As a oneliner:

print('\n'.join(c for c in string if c.isdigit()))

Answer 2

I think isdigit() can work, also you can use regex. https://www.w3schools.com/python/ref_string_isdigit.asp

Answer 3

You are partially on the right track with using the type keyword, however, if you type in

type(<some variable>)

into the interpreter, you will always get an output similar to the form "<class '<type'>" where <type> is the type of your variable. You can use the practically with this code (it's an example so modify it for your purpose):

myvar = "some python string"

if type(myvar) == "<class 'str'>":
    # true
    print("Is a string")

now as you can imagine, this program would output

>>> Its a string

You can make this work with any type by changing the str part of the "<class 'str'>" block to the type that you are looking for (for example: "<class 'int'>" for integers).

Hope this helps!

Answer 4

This can be done with regular expressions, You can import re module in Python to use regular expressions:

import re
sentences = "th3is i1s anot4her ra2ndom strin5g"
num = re.findall("[0-9]", sentences)
print(num)

Basically, this code will return all numerical values in that string

Answer 5

Don't worry.. Everybody who is a master programmer today was once a beginner and therefore would have had all obvious basic questions:).

You can use, str.isnumeric() boolean check. By using that you can avoid the second for loop since the second for loop doesn't actually make sense here.

Here is the revised code-

string = "th3is i1s anot4her ra2ndom strin5g"
for char in string:
    if char.isnumeric():
        print(char)