Pointer declaration in C++ - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this pointer declaration code?

Consider the following C++ code snippet. What will be printed when it runs?

C++

#include <iostream>
int main() {
    int x = 10;
    int* p = &x;
    std::cout << *p << std::endl;
    return 0;
}

A Address of x

B 0

C Compilation error

D 10

💡 Hint

Remember that *p means the value pointed to by p.

The pointer p holds the address of x. Using *p accesses the value stored at that address, which is 10.

❓ Predict Output

intermediate

What is the value of variable 'p' after this declaration?

Look at this code snippet. What does the pointer 'p' hold immediately after declaration?

C++

int* p;

A It holds the address of some variable

B It holds nullptr

C It holds a garbage (undefined) value

D It holds 0

💡 Hint

Uninitialized pointers do not automatically point to nullptr.

Declaring a pointer without initializing it means it contains whatever random data was in memory at that location, called a garbage value.

❓ Predict Output

advanced

What error does this pointer declaration cause?

What error will this code produce?

C++

int* p = 5;

A Compilation error: cannot convert int to int*

B Runtime error: segmentation fault

C Warning but compiles

D No error, p points to address 5

💡 Hint

You cannot assign an integer directly to a pointer without casting.

Assigning an integer literal to a pointer without a cast is invalid in C++ and causes a compilation error.

❓ Predict Output

advanced

What is the output of this pointer declaration and dereference?

What will this program print?

C++

#include <iostream>
int main() {
    int x = 7;
    int* p = &x;
    *p = 20;
    std::cout << x << std::endl;
    return 0;
}

A 20

B Garbage value

C Compilation error

D 7

💡 Hint

Changing *p changes the value of x because p points to x.

The pointer p points to x. Changing *p changes x's value to 20, so printing x outputs 20.

🧠 Conceptual

expert

Which pointer declaration is correct for a pointer to a constant integer?

You want to declare a pointer that points to an integer value that cannot be changed through the pointer. Which declaration is correct?

A int* const p;

B const int* p;

C const int* const p;

D int const p*;

💡 Hint

The const keyword before int means the value pointed to is constant.

const int* p means p points to a constant int value (value cannot be changed via p). int* const p means p itself is constant (cannot point elsewhere), but value can change. const int* const p means both pointer and value are constant. int const p* is invalid syntax.