In the C++ programming language, decltype is an operator for querying the type of an expression. It was introduced in C++11. Its primary intended use is in generic programming, where it is often difficult, or even impossible, to express types that depend on template parameters.
As generic programming techniques became increasingly popular throughout the 1990s, the need for a type-deduction mechanism was recognized. Many compiler vendors implemented their own versions of the operator, typically called typeof, and some portable implementations with limited functionality, based on existing language features were developed. In 2002, Bjarne Stroustrup proposed that a standardized version of the operator be added to the C++ language, and suggested the name "decltype", to reflect that the operator would yield the "declared type" of an expression.
Augusta Ada King, Countess of Lovelace (10 December 1815 – 27 November 1852), born Augusta Ada Byron, was an English writer chiefly known for her work on Charles Babbage's early mechanical general-purpose computer, the analytical engine. Her notes on the engine include what is recognised as the first algorithm intended to be processed by a machine; as such she is sometimes considered the "World's First Computer Programmer".
She was the only legitimate child of the poet Lord Byron (with Anne Isabella Milbanke). She had no relationship with her father, who died when she was nine. As a young adult she took an interest in mathematics, and in particular Babbage's work on the analytical engine. Between 1842 and 1843 she translated an article by Italian mathematician Luigi Menabrea on the engine, which she supplemented with a set of notes of her own. These notes contain what is considered the first computer program—that is, an algorithm encoded for processing by a machine. Though Babbage's engine has never been built, Lovelace's notes are important in the early history of computers. She also foresaw the capability of computers to go beyond mere calculating or number-crunching while others, including Babbage himself, focused only on these capabilities.