String Formatting in Python: % vs. .format vs. f-strings — Which is Best and When?

String Formatting: % vs. .format vs. F-String Literal

Question 1:

Which string formatting method is most suitable and when?

Answer:

• Python <2.6: "Hello %s" % name - Backwards compatibility
• Python 2.6 : "Hello {}".format(name) - Improved syntax, more sophisticated
• Python 3.6 : f"Hello {name}" - F-strings, most concise and modern

Question 1.1:

Why is ".format" often preferred over "%"?

Answer:

• ".format" allows both positional and keyword arguments, avoiding potential type errors and ugly syntax.
• It presents a cleaner and more readable format.

Question 2:

When does string formatting occur, and how can runtime performance penalties be avoided?

Answer:

String formatting occurs during expression evaluation, not function calls. To avoid runtime penalties, minimize formatting within loops or performance-critical sections.

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