Python programming - how to find and list all capitalized letters in an input string

Question

I am working on a simple program that finds all the capitalized letters in an inputed string. However, I am stuck on getting the program to function properly. I did the bulk of the work, but I do not see why it does not work.

  import string

def string_upper(capz):
    BigLetters = input
    input = "Please enter a string"
    for char in capz:
        if char.isupper():
            BigLetters += char
    return BigLetters

print(string_upper)

Please keep in mind that I am relatively new to Python, with only roughly 3 months of experience. Any help is appericated!

Answer 1

Try this, it will give you a list of uppercase letters

def string_upper():
    big_letters = input("Enter String: ")
    uppers = [l for l in big_letters if l.isupper()]
    return uppers

if __name__ == '__main__':
    print(string_upper())

Or in one line of code

def find_caps():
    return [l for l in input("Enter String: ") if l.isupper()]

if __name__ == '__main__':
    print(find_caps())

if you don't want it as a list you can do this to get it back to a string

print("".join(find_caps()))

Answer 2

HexxNine already gave you a great answer, but I'll add some explanation as to what is wrong with what you posted.

def string_upper():
    chars = input("Please enter a string: ")
    cap_chars = []
    for char in chars:
        if char.isupper():
            cap_chars += char
    return cap_chars


print(string_upper())

You do not need to add import string in the beginning. If you are trying to get the initial string from the user, your function string_upper also does not need any arguments. In Python 3, input is a built-in function where the query prompt to the user ("Please enter a string") needs to be the input function's argument (comes in parentheses after input). I created an empty list cap_chars above which is then used to store any uppercase letters. You cannot call your function string_upper without at least empty parentheses behind it, ie you need to use string_upper() in case the function does not take any arguments or string_upper(some_argument) in case it takes a single argument.

If you do not want user input to be a direct part of the function, you can also pass a string as an argument or pass the user input like this:

def string_upper(chars):
    cap_chars = []
    for char in chars:
        if char.isupper():
            cap_chars += char
    return cap_chars


print(string_upper("ThiS iS a sTrInG"))  # just pass some string
print(string_upper(input("Please enter a string: ")))  # pass user input

HexxNine used a list comprehension in his solution which is a more elegant approach and is deemed "pythonic" because, well, list comprehensions are one of the features which make Python so neat. You might want to look up what a list comprehension is. Getting rid of another line:

def string_upper():
    chars = input("Please enter a string: ")
    return [c for c in chars if c.isupper()]

print(string_upper())

This would also work but is not as readable anymore, so I'd recommend using the previous solution:

def string_upper():
    return [c for c in input("Please enter a string: ") if c.isupper()]

print(string_upper())

Answer 3

Str="hello World this is newBie"
import string
ref=[i for i in string.ascii_uppercase]
capitals=[i for i in Str if i in ref]
print capitals

this could be more abstract solution

Answer 4

You can just do this:

import re
your_input_string = "Hi, this is a Test String"
capitals = re.findall(r'[A-Z]{1}', your_input_string) # ['H', 'T', 'S']

I am using Regular Experessions to match capital letters in your_input_string .
[AZ] will match any capital letter while {1} says to match single letters. findall() function simply returns a list of matched strings and hence we get a list of capital letters.