C-static
stackoverflow What does “static” mean in C?
I've seen the word static used in different places in C code; is this like a static function/class in C# (where the implementation is shared across objects)?
wikipedia Static (keyword)
In the C programming language (and its close descendants such as C++ and Objective-C), static is a reserved word controlling both lifetime (as a static variable) and visibility (depending on linkage). The word static is also used in languages influenced by C, such as Java.
In C, static is a storage class (not to be confused with classes in object-oriented programming), as are extern, auto and register (which are also reserved words). Every variable and function has one of these storage classes; if a declaration does not specify the storage class, a context-dependent default is used:
externfor all top-level declarations in a source file,autofor variables declared in function bodies.
| Storage class | Lifetime | Visibility |
|---|---|---|
extern |
program execution | external (whole program) |
static |
program execution | internal (translation unit only) |
auto, register |
function execution | (none) |
In these languages, the term "static variable" has two meanings which are easy to confuse:
- A variable with the same lifetime as the program, as described above (language-independent); or
- (C-family-specific) A variable declared with storage class
static.
Variables with storage class extern, which include variables declared at top level without an explicit storage class, are static in the first meaning but not the second.