Specifiers AUTO Key word auto precedes the normal variable declaration All local variables are auto by default Created when function is called and destroyed when function terminates Life time of function run time ID: 505332
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Slide1
Storage Class SpecifiersSlide2
AUTO
Key word auto precedes the normal variable declaration
All local variables are auto by default
Created when function is called and destroyed when function terminates
Life time of function run time
Local auto variables have function scope
Can be applied only to local variablesSlide3
REGISTER
Keyword register is used
It is an auto declaration
Has all features of an auto variable
Provide faster access compared to other variables since they are stored in CPU registers
*
rather than memory
Can be applied only to local variables
*
a processor register is a small amount of storage available as part of a CPU or other digital processor.Slide4
STATIC
1) static global variable
* variable is globally available for the file in which it appears
Cannot be accessed from other files
2) Static Local variable
Created when the function is called
Not destroyed when the function is terminated.
Rather, value is retained in memory.
But, can be accessed only inside the function
Hence, it has function scope and program run life timeSlide5
EXTERN
Used when a program is spread across files
A
global variable
can be created with keyword
extern
(extern variable cannot be created locally)
Can be accessed across files.
Tells the compiler that variables and names declared as extern have been declared else where and fresh memory need not be allocated to these variables
Has file scope and program runtime.Slide6
Storage class specifiers
for Functions
By
default
, C++ functions have
program life time
and can be shared
across files
.
If declared static, the function has file scope.
Ie
, can be used only inside the file in which it appears and another file can use the same name for a
different function.
If declared extern, it means that the function has been defined in another file.
Useful for programs spread across files.Slide7
#include<
iostream.h
>
#include<
conio.h
>
void print()
{
static
int
x=1;
int
i
;
for(
i
=0;i<10;i++)
x++;
cout
<<"\n\n x= "<<x;
}
void main()
{
clrscr
();
cout
<<"First call...";
print();
cout
<<"\n\
nSecond
call..";
print();
getch
();
}
Out put:-
First Call…
11
Second call….
21