Auto:
Variables
with automatic storage duration are
created when the block in which they’re defined is entered; they exist while
the block is active, and they’re destroyed when the block is exited.
Only
variables can have automatic storage
duration.
A
functions local variables (those declared
in the parameter list or function body) normally have automatic storage
duration.
Keyword
auto explicitly declares variables of
automatic storage duration.
#include<stdio.h>
#include<conio.h>
void
fun();
int
main()
{
auto
int a;
clrscr();
a=10;
printf(“a=%d\n”,a);
{
int
a=20;
printf(“a=%d\n”,a);
}
printf(“a=%d\n”,a);
fun();
printf(“a=%d\n”,a);
getch();
return
0;
}
void
main()
{
int
a=30;
printf(“a=%d\n”,a);
}
OUTPUT:
a=10
a=20
a=10
a=30
a=10
For
example, in the program shown on the screen the following declaration indicates
that int variable ‘a’ is an automatic
local variable and exists only in the body of the function or the block in
which the declaration appears:
auto
int a;
local
variables have automatic storage duration by default, so keyword auto is rarely
used.
