What are Runes in Go, and How Do They Work?

Exploring the Enigma of Runes in Go

Often encountered in Golang, the term "rune" sparks curiosity yet leaves many puzzled. Amidst the sparse documentation, we delve deeper to unravel its enigmatic nature.

Defining Runes: A Numerical Representation of Unicode

In Go, a rune is an alias for an integer type. It represents Unicode codepoints, essentially numerical values assigned to characters in different languages. For instance, the rune 'a' corresponds to the integer 97, mirroring ASCII's numeric representation for lowercase characters.

Unveiling the Rune's Intricacies

The provided SwapRune function illustrates how runes are manipulated in code. It employs a series of conditions to transform runes between uppercase and lowercase by adding or subtracting 32, the difference between corresponding Unicode codepoints.

Deciphering the Conditional Expressions

Let's dissect the conditional expressions in the SwapRune function:

• 'a' <= r && r <= 'z' checks if the rune is a lowercase letter from 'a' to 'z' (97 to 122 in integer values).
• 'A' <= r && r <= 'Z' verifies if the rune is an uppercase letter from 'A' to 'Z' (65 to 90).

The Missing Argument in Switch

The switch statement in SwapRune operates without any arguments because it checks the value of the r rune variable, which is implicitly determined by the function's input.

The Curious Role of &<<" (and)

The &<<' operator in the condition is used to perform a bitwise logical AND operation, ensuring that both the left and right operands evaluate to true for the condition to hold. In the context of the function, it verifies that the rune falls within the specified range of lowercase or uppercase letters.

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