The set of all global variables is known as the global environment or global state. In the c programming language, and its predecessor b, an external variable is a variable defined outside any function block On the other hand, a local (automatic) variable is a variable defined inside a function block As an alternative to automatic variables, it is possible to define variables that are external to all functions, that is, variables that can be accessed by name by any function. Data segment in computing, a data segment (often denoted.data) is a portion of an object file or the corresponding address space of a program that contains initialized static variables, that is, global variables and static local variables. Scope (computer science) in computer programming, the scope of a name binding (an association of a name to an entity, such as a variable) is the part of a program where the name binding is valid
That is, where the name can be used to refer to the entity. Singletons are often preferred to global variables because they do not pollute the global namespace (or their containing namespace) Additionally, they permit lazy allocation and initialization, whereas global variables in many languages will always consume resources [1][3] the singleton pattern can also be used as a basis for other design patterns, such as the abstract factory, factory. There is also the concept of instance variables, where a class variable is bound to a class instance. Variable lifetime is contrasted with scope (where a variable can be used)
In many languages, global variables are always static, but in some languages they are dynamic, while local variables are generally automatic, but may be static.
OPEN
