strings in python

string

A sequence of characters inside quotes (” “ or ’ ’).

Can strings contain spaces, digits, or special characters?

Yes, they can contain all of those.

Are strings mutable or immutable in Python?

| Immutable (cannot be changed directly, but new strings can be created).

How do you access the first character of a string?

string[0].

How do you access the last character of a string?

string[-1].

What is slicing?

Extracting a part of a string: string[start:end:step]

What does len(string) return?

The number of characters in the string.

How to concatenate strings?

With +

How to repeat a string?

With * (e.g., “Hi” * 3 → “HiHiHi”)

What does \n mean?

New line

What does \t mean?

Tab

What does \ mean?

A backslash

What is a raw string?

A string with r”” that treats backslashes literally (e.g., r”C:\new\test”)

What does .upper() do?

Converts string to uppercase

What does .replace(“old”,“new”) do?

Replaces substring with new text

What does .find(“sub”) do?

Returns index of first match, or -1 if not found

What are 3 main ways to format strings?

f-strings, .format(), % operator

Example of f-string?

f”My name is {name}”

Example of .format()?

“My name is {}”.format(name)

Example of % operator?

“My name is %s” % name

What is regex used for?

Pattern matching in strings

Common regex functions?

search, findall, split, sub

What does \d match?

Any digit

What does \D match?

Any non-digit

What does \w match?

Any word character (letters, digits, _)

What does \W match?

Any non-word character

What does \s match?

Any whitespace

What does \S match?

Any non-whitespace

What does \b match?

Word boundary

What does \B match?

Not at word boundary

What does re.split(r”\s”, text) do?

Splits text by whitespace

What does re.sub(pattern, replacement, text do?

) | Replaces matches with replacement