How to add a string in a certain position?

Examining string immutability and slicing

In Python, strings are immutable. This means once a string is created, it cannot be changed. However, this does not mean we can't generate a new string based on an existing one. Python has a powerful feature known as slicing for accessing parts of a string. For instance, s[:4] + '-' + s[4:] can be used to insert a dash into the string "3655879ACB6" at the fourth index:

s = "3655879ACB6"
print(s[:4] + '-' + s[4:])  # Prints: 3655-879ACB6 (looks like a hidden code, huh? 😉)
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Building a custom function for string insertion

You can build a custom insert_string function for repeated string insertions. It accepts three arguments: original, insert, and index:

def insert_string(original, insert, index):
    return original[:index] + insert + original[index:]

print(insert_string('3655879ACB6', '-', 4))  # Prints: 3655-879ACB6 (secret agent code activated! 🕵️‍♂️)
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Let's play with lists

An alternative to string slicing and concatenation is to convert the string into a list, then use list.insert() to add the new string, and finally join it back into a string with ''.join(). It might be slower but sometimes it feels more intuitive especially with multiple insertions and modifications:

s = "3655879ACB6"
s_list = list(s)
s_list.insert(4, '-')
s = ''.join(s_list)
print(s)  # Prints: 3655-879ACB6 (breaking codes, Python style! 🐍)
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Slicing vs list conversion: Performance considerations

In the battle of performance, slicing with a sword ⚔️ often defeats converting to a list and back. Especially when the string is particularly long, slicing is the speedy conqueror. Use slicing as your default strategy for small, straightforward insertions.

Never underestimate the power of slicing!

Python slicing is like a Swiss knife 💡 in the world of strings. It not only lets you add any string to any position, but you can use it to replace or even remove parts of a string for effective string manipulation:

# Replacing a substring
s = "Hello World"
s = s[:6] + "Python" + s[11:]
print(s)  # Prints: "Hello Python" (Who needs the world, when you've Python?! 🌏 🐍)

# Removing a substring
s = "Hello Python World"
s = s[:6] + s[13:]
print(s)  # Prints: "Hello World" (Back to basics 🌏)
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Indexing insights

Understanding indexing in Python is key. We start counting at 0. For inserting at the start of a string, use index 0. For the end, use the length of the string:

s = "Welcome"
s = s[:0] + "Hello " + s[0:]  # Insert at start
print(s)  # Prints: "Hello Welcome" (Polite as a Canadian 🍁)
s = s[:] + "!"  # Insert at end
print(s)  # Prints: "Hello Welcome!" (Excited like a dog seeing its owner 🐕)
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Test cases are your friends

Make sure to test your functions with multiple cases, including edge ones like inserting at the beginning or end of a string, to make sure they work in all scenarios. Tests are like vaccines, they prevent future headaches! 💉

String methods are your tools

Learning various Python string operations can solve many problems effectively. replace(), join(), and many more are there to help. These are your lightsabers in the fight against string problems. 🌌