Get the last 4 characters of a string

Be careful: String too short

When your string contains less than 4 characters, no worries! The same slicing method works perfectly:

short_string = "Lot"
last_four = short_string[-4:]  # Four shall not pass but "Lot" certainly does!
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last_four will merely be "Lot".

Edges of the Python universe

Empty strings are like black holes: they suck every character in, leaving an empty substring:

empty_string = ""
last_four = empty_string[-4:]  # Expects nothing, delivers nothing.
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Python slicing dodges IndexError, unlike direct index access. Good when sliding along a string, bad when expecting an error.

Twist and turn: Variations

Reversing and slicing

You can reverse the string, then get the first 4 characters:

reversed_four = my_string[::-1][:4][::-1]
# This could turn a Python into a nohtyP!
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Function extraction

Use a function if longevity is your goal and those last few characters seem very attractive:

def get_last_n_chars(string, n):
    return string[-n:] if len(string) >= n else string

# Usage:
last_four = get_last_n_chars("Programming", 4)
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Conditional slicing

When you're unsure about getting your hands (or slice) all the way to the end:

last_four = my_string[-4:] if len(my_string) >= 4 else my_string
# Here's to optional commitment!
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This approach employs the ternary operator to make an informed decision: slice or return the whole string.

Practical applications

Substrings can be key information vectors, and string slicing a master key. Practical examples are file extensions, ID codes, or data formatting.

File extension parsing

Extract extension from file names:

file_name = "selfie.jpg"
extension = file_name[-4:]  # As long as your extension doesn't suffer from chararter-limit condition!
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ID numbers and special codes

Working with identification numbers with last few digits as checksum or SPC (Special Python Code):

id_number = "1234-5678-91238"
check_code = id_number[-4:]
# "1238" is suspicious. I bet it ate "7"!
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