What is global variable in C programming?

Answer 1

A global variable is a variable that is declared at global scope, rather than file, namespace, function, class or nested scope. Global variables are usually declared with external linkage within a header and initialised in one (and only one) source file. Any file that includes the header (which includes the source file that initialised the global variable) then has unrestricted access to the variable. It is globally visible and any code can alter it.

Global variables should be used sparingly and only when absolutely necessary. If the vast majority of the functions in your program require access to a particular variable, then a global variable makes perfect sense and is by far the simplest solution. However, a variable that is only used by a handful of functions can hardly be described as a global entity, thus it has no place within the global namespace and should be scoped to those functions that actually require it instead.

Answer 2

Global variables are named storage locations that are allocated (and possibly initialized) when the program is loaded. Global variables are accessible by name from within any function. In C source, a global is a variable that is declared outside of any function, without an extern or static storage class specifier.

The use of global variables without good justification is generally considered bad programming style, as it creates cohesion between functions and between modules, allows functions to have side-effects, and causes lots of confusion if some functions declare automatic variables with the same names as global variables.

Answer 3

The question should be "what is ... definition ...?" It does not really matter where you declare a variable. Declaration is only a compiler directive telling it information about an object you intend to define later. Definition is what is important. Declaration and definition can be done at the same time, however; its just that they are two distinct actions. Global definition, now, is where the variable (or object) is defined at file scope, i.e. outside of any block, i.e. outside of any enclosing braces.

With global definition, you have global scope, i.e. visibility. Unless you also specified static, you also have program scope, i.e. inter-module scope or visibility.

Answer 4

When a variable is declared inside the function/ main functions, the variable is called a local variable.

On the other hand, when a variable is declared outside of the function/main function, the variable is called a global variable.

For Example:

#include

int a;

int main()

{

int c;

return 0;

}

On the above program "int c" is a local variable & "int a" is a global variable.

Answer 5

Global variables can be seen in all blocks of your program, when local variables are visible only within the block where it's declared. hope this helps ...harry hill

Answer 6

When the scope of the variable is throughout then such variable is called global.