Explaining the Python % Sign: A Beginner’s Guide

In Python, the percent sign (%) is used for string formatting as well as for modulo operations.

String Formatting

The % operator is used to format a string by replacing a placeholder in the string with a value. The placeholder is represented by a percent sign followed by one or more of these special characters:

• %s: String (or any object with a str() method)
• %d: Integer
• %f: Floating-point decimal

Here is an example of using the % operator for string formatting:

name = 'John'
age = 30

print('Hello, my name is %s and I am %d years old' % (name, age))
Code language: PHP (php)

Output:

Hello, my name is John and I am 30 years old

However, it is worth noting that this is an old-school way of formatting strings and these days you should use f-strings instead.

Use f-strings instead of % for String Formatting

f-strings (short for “formatted strings”) are a convenient and powerful way to embed expressions inside string literals, making it easier to format strings and embed variables. They were introduced in Python 3.6 and have since become a popular choice for string formatting in Python.

F-strings offer several advantages over other string formatting methods in Python, such as the older % string formatting operator and the format() method. Some of the benefits of using f-strings include:

1. Improved readability: F-strings allow you to embed expressions directly inside string literals, making your code more readable and easier to understand.
2. Increased performance: F-strings are generally faster than other string formatting methods, as they are evaluated at runtime rather than being compiled.
3. Greater flexibility: F-strings allow you to use any valid Python expression inside the curly braces, giving you more flexibility when formatting strings.
4. Easier debugging: F-strings include the expression and its result directly in the string, making it easier to debug your code by printing out the values of variables.

Modulo Operation

The % operator is also used to perform the modulo operation, which returns the remainder of a division. For example:

print(10 % 3)  # Output: 1
print(11 % 3)  # Output: 2
print(12 % 3)  # Output: 0
Code language: PHP (php)

The modulo operator is often used to perform operations on integers that repeat in a cycle, such as wrapping around an array index or incrementing a clock.