How to Use Python f-string, String Format, and String Template to Format String Output

1. Using f-string (formatted string literals).

Python f-strings provide a concise and readable way to embed expressions inside string literals, using curly braces `{}`.

def use_f_strings():

    # Using f-strings
    language = "Python"
    rank = 1
    print(f"{language} is number {rank}!")

    name = "Alice"
    age = 30
    formatted_string = f"Name: {name}, Age: {age}"
    print(formatted_string)


if __name__ == "__main__":

    use_f_strings()

2. Using `str.format()` method.

The `str.format()` method allows for more complex string formatting and is available in all versions of Python starting from 2.7.

def use_str_format():

    language = "Python"
    rank = 1

    # Using str.format()
    print("{} is number {}!".format(language, rank))
    print("{language} is number {number}!".format(language="Python", number=1))  # Output: Python is number 1!

    name = "Bob"
    age = 25
    formatted_string = "Name: {}, Age: {}".format(name, age)
    print(formatted_string)


if __name__ == "__main__":

    use_str_format()

3. Using `string.Template`.

The `string.Template` class in the `string` module provides a way to substitute values into strings using placeholders.

from string import Template

def use_string_template():

    name = "Carol"
    age = 35
    template = Template("Name: $name, Age: $age")
    formatted_string = template.substitute(name=name, age=age)
    print(formatted_string)


if __name__ == "__main__":

    use_string_template()

Each of these methods has its own use case, with f-strings being the most concise and readable for most modern Python code, `str.format()` offering flexibility for complex formatting needs, and `string.Template` providing a straightforward option for situations requiring simpler and safer substitution (e.g., when dealing with user-provided templates).

4. Example Demo Video.