C-sharp (C♯, C#)

C♯ in music

In musical notation C♯ is the pitch a semitone above C and a semitone below D in equal temperament. Depending on octave it appears in scales and keys such as C♯ major and C♯ minor. C♯ major is one of the few major keys that uses seven sharps in its key signature; C♯ minor, its relative minor, uses four sharps. The precise frequency of a given C♯ depends on the tuning system; in modern concert pitch where A4 = 440 Hz, the note commonly labeled C♯4 has a frequency near 277 Hz.

C# the programming language

C# (pronounced "see sharp") is a statically typed, object-oriented language developed under the leadership of Anders Hejlsberg for Microsoft as part of the .NET initiative. It was designed to be simple, modern and safe, incorporating features such as strong typing, automatic memory management (garbage collection), generics, lambda expressions, and language-integrated query (LINQ). C# source code is typically compiled into an intermediate language that runs on the Common Language Runtime (CLR), enabling interoperability with other .NET languages.

Characteristics and ecosystem

• Language features: classes, interfaces, delegates, events, properties, async/await, and pattern matching.
• Runtime: originally tied to the .NET Framework; later versions run on cross-platform .NET implementations (formerly .NET Core).
• Common uses: enterprise applications, web services, desktop apps, mobile apps (via Xamarin), and game scripting (notably in Unity).

History and standards

C# emerged around the turn of the 21st century as Microsoft built the .NET platform. It quickly gained popularity for enterprise development and has evolved through multiple language versions, each adding capabilities for safer, more expressive code. The language has been formalized through industry standards and is supported by a rich tooling ecosystem, including compilers, integrated development environments, and package managers.

Distinctions and notable facts

The written forms C♯ and C# serve different audiences: musicians use the sharp sign (♯), while programmers commonly use the hash sign (#) because of keyboard conventions. Despite the shared name, the musical and computing senses are unrelated beyond their label; the programming name alludes metaphorically to musical notation and to an evolution beyond the C family of languages. Both meanings are widely encountered in music theory and software development respectively, making context essential when the term appears.