THINK++ — Engineering Visualized

Safety First

Null Pointers

A null pointer is a pointer that doesn't point to any valid memory location. It represents the "empty" or "not set" state.

MODERN C++ (C++11+)

int* ptr = nullptr;

Always use nullptr instead of NULL or 0. It is type-safe and prevents ambiguity with integer types.

The Null Check

if (ptr != nullptr) {
    cout << *ptr; // Safe to dereference
} else {
    cout << "Pointer is empty";
}

SEGMENTATION FAULT

Dereferencing a null pointer (*ptr when ptr is null) will cause your program to crash immediately. This is the most common cause of "Segmentation Fault".

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