nullptr
- C++ course
- Beginner
- Lesson 80/116
- 5 min
Learn the modern null pointer concept with nullptr.
nullptr
nullptr is the pointer value meaning 'points nowhere'. In old C++ you would use NULL or 0, but modern C++ prefers nullptr because it is type-safe.
Initializing a pointer with int* p = nullptr; states clearly that p has no target yet. Later you can check whether it is empty with if (p == nullptr). This is the safety check before dereferencing.
Null check
Before dereferencing a pointer with *p, it is a good habit to check whether it is null. Dereferencing a null pointer is undefined behavior; the program may crash.
The check: if (p != nullptr) { std::cout << *p; }. This prints the value only if p is not null. Null pointers are an explicit way to express 'no target yet'; so you meet them often in modern C++ code.
Practice Null pointer check
Declare int* p = nullptr;. Check with if (p == nullptr); if true, print "Boş" with std::cout (with a newline).
Starter code
#include <iostream>
int main() {
// Set p to nullptr
// Check if it is null
// Print Boş
return 0;
}Sample solution
#include <iostream>
int main() {
int* p = nullptr;
if (p == nullptr) {
std::cout << "Boş\n";
}
return 0;
}Expected output
Boş
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 nullptr assignment
int* p = ____;int* p = nullptr;Explanation: int* p = nullptr; makes p a null pointer.
2 What is nullptr?
- A value that points nowhere Correct answer
- An empty variable
- A pointer type
- A reference
Explanation: nullptr is the pointer value that points nowhere.
3 Match each expression to its meaning
| Term | Meaning |
|---|---|
nullptr |
Null pointer |
if (p == nullptr) |
Check |
int* |
Pointer type |
p == nullptr |
Comparison |