## What is the Mystery Behind the Expression \'<:]{%>\' in C ?

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Unveiling the Enigmatic Smile: <:>

In the realm of programming, curiosity often leads to encounters with intriguing expressions. As you delve into a compilation, you may stumble upon a perplexing sequence: <:>. Unlike many expressions that trigger errors or warnings, this one blends effortlessly into the code. But what lies beneath its cryptic exterior?

Digraphs, a lesser-known aspect of C , hold the key to understanding this mysterious expression. They enable the representation of certain symbols using character combinations. In this case, <: and> translate to [, respectively. Substitution reveals the true nature of the expression as a lambda expression: [] {};.

Lambda expressions, also known as anonymous functions, serve the purpose of placeholders or dummy functions without any actual implementation. They are commonly used to hold the spot for a function pointer or a function object. The lack of any discernible behavior in this specific example signifies its placeholder nature.

Despite the rarity of their use today, digraphs provide a valuable solution in circumstances where keyboards lack essential keys for C 's basic source character set. They allow programmers to represent graphical characters like braces and parentheses through a combination of alternate characters. This accommodation caters to variations in hardware and software capabilities, ensuring seamless compilation even in resource-constrained environments.

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