Storage Classes, auto, extern, static, register | C Programming | Bengali скачать в хорошем качестве

Storage Classes, auto, extern, static, register | C Programming | Bengali

C - Scope Rules A scope in any programming is a region of the program where a defined variable can have its existence and beyond that variable it cannot be accessed. There are three places where variables can be declared in C programming language 1. Inside a function or a block which is called local variables. 2. Outside of all functions which is called global variables. 3. In the definition of function parameters which are called formal parameters.   Initializing Local and Global Variables When a local variable is defined, it is not initialized by the system, you must initialize it yourself. Global variables are initialized automatically by the system when you define them as follows − Data Type Initial Default Value int 0 char '\0' float 0 double 0 pointer NULL Storage Classes in C Storage Classes are used to describe the features of a variable/function. These features basically include the scope, visibility and life-time which help us to trace the existence of a particular variable during the runtime of a program. It tells us: 1. Where the variable would be stored. 2. What will be the initial value/default of the variable? 3. What is the scope of the variable? 4. What is the life of the variable? i.e how long would the variable exist. C language uses 4 storage classes, namely: 1) auto 2) extern 3) static 4) register Storage Classes Storage Place Default Value Scope Lifetime auto RAM Garbage Value Local to the block where it is defined. Till the control remains within the block. extern RAM Zero Global Till the end of the main program. static RAM Zero Local to the block where it is defined. Till the end of the main program. register CPU Register Garbage Value Local to the block where it is defined Till the control remains within the block.