------------------------------------- Test Your "C" Skill ---------------------------------------
DECLARATIONS AND INITIALIZATION:
1.
#include<stdio.h>
void main()
{
char var *s1,*s2;
printf(""%d%d",sizeof(s1),sizeof(s2));
}
Outout:-
4 2
2.
#include<stdio.h>
int x=40;
void main()
{
int x=20;
printf("%d",x);
}
Outout:-
20
3.
#include<stdio.h>
void main()
{
int x=40;
{
int x=20;
printf("%d",x0;
}
printf("%d",x);
}
Output:-
20 40
4.
Is the following
statement declaration or definition
extern int x;
Output:-
Declaration
5.
#include<stdio.h>
main()
{
extern int i;
i=20;
printf("%d",sizeof(i));
}
Output:-
Error,i undefined
Because extern int i is a declaration and
not definition
6.Is it true that the
global variable have many declarations but only one definition?
Output:-
yes
7.Is it true that the
function may have many declarations but only one definition?
output:-
yes
8.what is the
difference between declaration and definition of a variable
Output:-
Declaration:-only
gives the type,status and nature of variable without reserving any space for the variable
Definition:-actual space is reserved for the
variable and some initial value is given.
9.if the definition of
the external variable occurs in the source file before it's use in a
particular function then there is no need
for an external declaration in the function
Output:-
True
10.suppose the program
is divided in three source files f1,f2,f3 and the variable is defined in file f1 but used in f2 and f3. In such a
case would we need the external declaration for the variable in files f2 and f3?
Output:-
yes
10.what is the difference
between following declarations
extern int fun()
int fun();
Output:-
Nothing except that
that the first one gives us hint that function fun is probably in another file.
10. why does the following program reports the re declaration error of function display()
#include<stdio.h>
void main()
{
dispaly();
}
void dispaly()
{
printf("Hello world");
}
Output:-
Here the function
display() is called before it is declared .That is why the compiler assumes it
to be declared as
int display();
That accept unspecified no of arguments.i.e.
undeclared function assumes to return int
On appearing the declaration the fun shows
that it returns void hence the error
11.
void main()
{
extern int fun(float);
int a;
a=fun(3.14);
printf("%d",a);
}
int fun(aa) /* K & R style of function definition*/
float aa
{
return((int)aa);
}
Output:-
Error
Because we have mixed the ANSI prototype
with k & r style of function definition
If we use an ANSI prototype and pass float
to the function then it is promoted to double the function accepts it in to variable of
type float hence the type mismatch occurs To ready the situation define the
function as
int fun(float aa)
{
.....
}
12.point error if any
struct emp
{
char name[20];
int
age;
}
fun(int aa)
{
int bb;
bb=aa*aa;
return(bb);
}
main()
{
int a;
a=fun(20);
printf("%d",a);
}
Output:-
Missing semicolon
at the end of struct due to which the function fun assumed to be
returning void of type struct emp.
But it returns an int hence the error
13.Correct the error
fun(struct emp);
struct emp
{
char name[20];
int age;
};
void main()
{
struct emp e={"Mukesh",21}
fun(e);
}
fun(struct emp ee)
{
printf("\n %s
%d",ee.name,ee.age);
}
Output:-
Declare the structure before the prototype
of fun().
14.What would be the output
of the following program
void main()
{
int a[5]={2,3}
printf("\n %d %d
%d",a[2],a[3],a[4]);
}
Output:-
0 0 0
If a automatic array is partially
initialized then remaining elements are initialized by 0
15.void main()
{
struct emp
{
char name[20];
int age;
float sal;
};
struct emp e={"Mukesh"}
printf("\n %d %f",e.age, e.sal);
}
Output:-
0 0.000000
If an automatic structure is partially
initialized then remaining elements are initialized by 0.
16.point out error
void main()
{
int(*p)()=fun;
(*p)();
}
fun()
{
printf("\n Hello World");
}
Output:-
Here we are initializing function pointer to address of the function fun() but during the time of initialization the function has not
been defined.
Hence an error To eliminate the error add the prototype of
function fun() before the declaration of p, as shown bellow;
extern int fun(); or
int fun();
17.point error if any
void main()
{
union a
{
int i;
char ch[2];
};
union a z=512;
printf("%d %d",z.ch[0],z.ch[1]);
}
Output:-
In Pre-ANSI compiler union variable can not be initialized . ANSI compiler permits initialization of
first member of the union
18.What do you mean by
the scope of the variable? what are the 4 different types of scopes that a
variables can have?
Output:-
Scope indicates the
region over which the variable's declaration has an effect. The four kinds of
scopes are:
---file
---function
---block
---prototype.
19. what are different types
of linkages?
Output:-
There are three
different types of linkages : external , internal , and none.
---External linkage
means global, non-static variables and functions,
---Internal linkage
means static variables and functions with file scope
--- None linkage means local variables.
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