Lecture 4: Characters and Pointers #

What will be the output ?

char ch = 'a';
char* ptr = &ch;
ch++;
cout << *ptr << endl;

Options

a. a
b. b
c. 97
d. 98
Correct Answer 
b. b
This should print all characters until it reaches a null character. But we can assume that the next one is a null character.

Assume address of 0th index of array ‘b’ is 200. What is the output ?

char b[] = "xyz";
char *c = &b[0];
cout << c << endl;

Options

a. 200
b. x
c. xyz
d. None of these
Correct Answer 
d. xyz
This should print all characters until it reaches a null character.

Assume that address of 0th index of array ‘a’ is : 200. What is the output ?

char b[] = "xyz";
char *c = &b[0];
c++;
cout << c << endl;

Options

a. 201
b. y
c. xyz
d. yz
Correct Answer 
d. yz
This should print all characters until it reaches a null character.

Fill the output ?

char s[]= "hello";
char *p = s;
cout << s[0] << " " << p[0];

Answer

____
Correct Answer 
h h
Why not hello hello or h hello? As we have used bracket notation, dereferencing has been done, and dereferencing happens according to the jump.
The only anomaly is with character addresses(pointers and array_names), where instead of displaying the hex address, we get the derefenced char values till EOS.

Lecture 5: Pointers and Functions #

Figure out the correct output of the following code.

void changeSign(int *p)
{
    *p = (*p)  *  -1;
}

int main()
{
    int a = 10;
    changeSign(&a);
    cout << a << endl;
}

Options

a. -10
b.  10
c.  Error
d. None of the above
Correct Answer 
-10
We made changes at the address, and it will surely be reflected.

Fill the output

void fun(int a[])
{
    cout << a[0] << " ";
}

int main()
{
    int a[] = {1, 2, 3, 4};
    fun(a + 1);
    cout << a[0];
}

Answer

____
Correct Answer 
2 1
Obvious.

What will be the output ?

void square(int *p)
{
    int a = 10;
    p = &a;
    *p = (*p) * (*p);
}

int main()
{
    int a = 10;
    square(&a);
    cout << a << endl;
}

Options

a. 100
b. 10
c. Error
d. None of these
Correct Answer 
10
No changes were made at the location of the argument.

Lecture 6: Double Pointer #

What will be the output ?

int a = 10;
int *p = &a;
int **q = &p;
int b = 20;
*q = &b;
(*p)++;
cout << a << " " << b << endl;

Options

a. 10 21
b. 11 20
c. 11 21
d. 10 20
Correct Answer 
a. 10 21
Use the diagram rules.

What will be the output ?

int a = 100;
int *p = &a;
int **q = &p;
int b = (**q)++ + 4;
cout << a << " " << b << endl;

Options

a. 100 104
b. 101 104
c. 101 105
d. 100 105
Correct Answer 
a. 101 104
++ is evaluated after the statement ends. Safe assumption.

What will be the output ?

int a = 100;
int *p = &a;
int **q = &p;
int b = (**q)++;
int *r = *q;
(*r)++;
cout << a << " " << b << endl;

Options

a. 102 100
b. 101 100
c. 101 101
d. 102 101
Correct Answer 
a. 102 100
Draw a diagram.

What will be the output ?

void increment(int **p)
{
    (**p)++;
}

int main()
{
    int num = 10;
    int *ptr = &num;
    increment(&ptr);
    cout << num << endl;
}

a. 10
b. 11
c. Error
d. None of these
Correct Answer 
b. 11
The function changes the value at the address.

End Of Quiz #