Python - Create a string made of the first and last two characters from a given string

To solve the problem, we need to create a new string that combines the first two and the last two characters of a given string. If the input string is too short (less than 2 characters), we should return an empty string. This task is simple and can be achieved using a variety of methods.

Using slicing

This method uses Python's slicing feature to extract the required characters from the string.

s = "geeksforgeeks"

# Check if the string is long enough
if len(s) >= 2:
    # Combine first two and last two characters
    result = s[:2] + s[-2:]
else:
    # Return empty string for short inputs
    result = ""
print(result) 

geks

Explanation:

• Slicing s[:2] extracts the first two characters.
• Slicing s[-2:] extracts the last two characters.
• These are concatenated to form the result.
• If the string has fewer than two characters, it returns an empty string.

Using list comprehension

This method uses a concise, list-based approach to solve the problem.

s = "hello"

# Combine first two and last two characters using list comprehension
result = "".join([s[:2], s[-2:]]) if len(s) >= 2 else ""
print(result)  

helo

Explanation:

• join()method combines the sliced parts of the string.
• A conditional expression ensures that for strings shorter than two characters, an empty string is returned.

Using regular expressions

This method uses Python's re module for pattern matching. While not necessary for simple cases, regular expressions are useful for complex scenarios.

import re

# Input string
s = "geeks"

# Use regex to extract first and last two characters
result = s[:2] + s[-2:] if len(s) >= 2 else ""
print(result)  

geks

Explanation:

• While regular expressions are not necessary for this problem, they can handle more complex requirements if needed.
• For this problem, s[:2] + s[-2:] is directly applied to achieve the result efficiently.

Using conditional logic

This method implements inline conditional logic for compactness.

# Input string
s = "world"

# Use a conditional expression to generate the result
result = s[:2] + s[-2:] if len(s) >= 2 else ""
print(result) 

wold

Explanation:

• The conditional expression directly checks the string length and generates the desired output.
• It avoids the need for additional libraries or functions, making it a simple and lightweight approach.