1. int *ptr ; What are we doing here ? 2. int x = 10; int *ptr = x ; printf (\"

Question

1.

int *ptr ;

What are we doing here ?

2. int x = 10;

int *ptr = x ;

printf (" %d ", *ptr) ;

A programmer wrote the above code in an application. Is there a problem in the code ?

3.

Are these two version of the code work the same or different?

Version 1:

int x = 10;

int y = x;

version 2:

int x = 10;

int *ptr = &x ;

int y = *ptr ;

4.

if

int *ptr = x ;

then the variable x should be defined as

a. int x;

b. float x;

c. int *x;

d. All of the above

5.

int *x ;

int iA [ 4 ] ;

iA = x ;

Is the above statement valid ?

Consider this code

int *x;

int iA [ 4 ] ;

6.

x = iA ;

To which cell is x pointing to ?

7. In the above program clip,

x = ( iA + 3 ) ;

Now, to which cell does x points to ?

8.

in the same code above, if we change

x = iA + 5;

Is the above statement (though valid), result in good working code ?

9.

using the same code above, Consider this

x = iA ;

we now want to print all values in the array using a for loop.

how would you print all values using the pointer x

10.

unsigned char *ptr ;

unsigned int iA [ 2 ] = { 0x01020304, 0x05060708} ; // integer array

ptr = iA ; // we made char pointer point to a integer array

ptr = iA + 1 ;

printf (" %d ", *ptr);

What would be printed ?

Explanation / Answer

1.int *ptr ;
Ans: Here we declaring pointer of integer type.

2. int x = 10;
int *ptr = x ;
printf (" %d ", *ptr) ;
Ans: Pointer always store the address of value.
So there is a error in second line.
Correct Statement is: int *ptr = &x;

3.Are these two version of the code work the same or different?

Version 1:
int x = 10;
int y = x;

version 2:
int x = 10;
int *ptr = &x ;
int y = *ptr ;

Ans: Both are same.

4.if
int *ptr = x ;
then the variable x should be defined as

a. int x;
b. float x;
c. int *x;
d. All of the above

Ans: int x.

5.
int *x ;
int iA [ 4 ] ;
iA = x ;
Is the above statement valid ?
Consider this code
int *x;
int iA [ 4 ] ;

Ans: No the above code is wrong.
Right code:
int *x ;
int iA [ 4 ] ;
x=iA ;

6.
x = iA ;
To which cell is x pointing to ?

Ans:First cell i.e iA[0].

7. In the above program clip,
x = ( iA + 3 ) ;
Now, to which cell does x points to ?

Ans:iA[3].

8.
in the same code above, if we change
x = iA + 5;
Is the above statement (though valid), result in good working code ?

Ans: Invalid, it will give error.

9.
using the same code above, Consider this
x = iA ;
we now want to print all values in the array using a for loop.
how would you print all values using the pointer x

Ans: for(i=0;i<4;i++)
       {
        print("%d",*(x+i));
       }

10.
unsigned char *ptr ;
unsigned int iA [ 2 ] = { 0x01020304, 0x05060708} ; // integer array
ptr = iA ; // we made char pointer point to a integer array
ptr = iA + 1 ;
printf (" %d ", *ptr);
What would be printed ?

Ans:0x05060708

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