Understanding f-strings in Python

Understanding f-strings in Python

The f in front of the quotes is for f-strings, which stands for formatted strings in Python. They allow you to embed expressions (like variables or calculations) directly inside a string by enclosing them in curly braces {}.

Why Use f-strings?

  1. Readable and concise: Easier to read and write compared to older formatting methods.
  2. Efficient: Faster and more efficient than older techniques like format() or % formatting.
  3. Flexible: Can embed any valid Python expression.

Example: Building a URL with f-strings

url = f"https://{fortigate_ip}/api/v2/monitor/system/interface/arp"

The value of fortigate_ip (which is "192.168.1.99") gets inserted into the string, making url equal to:

"https://192.168.1.99/api/v2/monitor/system/interface/arp"

Another Example: Embedding Variables in a String

name = "FortiGate"
version = "7.2.1"

print(f"My firewall is {name} running version {version}.")

Output:

My firewall is FortiGate running version 7.2.1.

Without f-strings

Before f-strings, you would have to use the format() method:

print("My firewall is {} running version {}.".format(name, version))

As you can see, f-strings are a cleaner, faster, and more modern approach to string formatting in Python.

f-strings were introduced in Python 3.6 and have since become the preferred way to format strings in modern Python code. If you’re writing automation scripts or working with APIs, f-strings can help make your code more readable and efficient.