In my opinion it is rarely a good idea to use global variables, unless you need to refer to them across modules, or their values need to be keep for a long period of program execution. Local variables should always be used when their lifetime is short, usually only in the module they are declared in.
Global variables lifetime will be for the length of the program execution.
Variables that are declared globally outside every program are called global variables.
Coupling is the interdependency of a program. A program that uses local variables is more independent than one that uses global variables. Therefore, the program would be considered to have lower coupling.
global
Global Variables Or: variables with names longer than 128 characters.
Global variables can be seen in all blocks of your program, when local variables are visible only within the block where it's declared.
The program's data segment. This area of memory is allocated by the linker and is used to store the program's global variables, static variables, static arrays and constants. Constants are always initialised, as are static variables, but global variables and static arrays need not be initialised.
The variables which are declared outside the main() function is known as global variables and they can be used anywhere in the program. And, the variables which used declare inside the main() function is known as local variables and they can be used inside the main() function only. Example: #include<stdio.h> #include<conio.h> int x,y; // global variables void main() { int a,b; // Local variables ------------ ---------------------- --------------------- getch(); }
C++ has 4 distinct regions for memory distribution Stack : This region is used for function calls' return addresses , arguments and local variables Heap : This region is for dynamic allocation of memory (dynamic variables created on run time use this memory , aka RAM) Global Variables : This is used for global variables defined by the programmer Program Code : This region is for the program code.
Extern and Global are the storage space in C program. Global provides us to access the variables from anywhere inside the program only whereas Extern provides us to access the variables from outside that program, i,e., some other program.
Global variables are globally accessible. Java does not support globally accessible variables due to following reasons:The global variables breaks the referential transparencyGlobal variables creates collisions in namespac
Another name of global variable is "EXTERNAL VARIABLES".
Local variables: These variables only exist inside the specific function that creates them. They are unknown to other functions and to the main program. As such, they are normally implemented using a stack. Local variables cease to exist once the function that created them is completed. They are recreated each time a function is executed or called. Global variables: These variables can be accessed (ie known) by any function comprising the program. They are implemented by associating memory locations with variable names. They do not get recreated if the function is recalled.