C++ Nullptr Vs Null

C++ Nullptr Vs Null: Understanding the Differences

C++ is a programming language that is widely used for developing various applications. When it comes to pointer initialization, C++ provides two options: nullptr and null. Although they may seem similar, these two can have significant differences in various applications.

Null Vs. Nullptr: Understanding the Basics

Before diving deeper into the differences between these two pointers, let’s first understand what they are. Null is a pointer that has a value of zero. On the other hand, nullptr is a pointer that is explicitly initialized to a value of zero.

Now that we understand the basics let’s explore the differences between these two pointers and when to use them.

Difference Between Nullptr and Null

– nullptr is a C++11 feature, whereas null has been present in earlier versions of C++.
– nullptr is a strongly-typed pointer, meaning that it can only be assigned to null pointer types, whereas null is available to any pointer type.
– Mixing nullptr with non-pointer types causes a compilation error whereas mixing null with non-pointer types is allowed.
– nullptr is safer when compared to null since it avoids accidental misuses.

Usage of Nullptr

The primary use of nullptr is to ensure that any null pointer is explicitly defined. The use of nullptr can also simplify your code and prevent any confusion that may arise when dealing with null pointers. This pointer is particularly useful when dealing with overloaded functions.

Consider the following example.

void myFunction(int param);
void myFunction(char *param);
void myFunction(int *param);

If you pass null instead of nullptr, you may encounter errors, while if you use nullptr, the compiler will tell you that there is an error because it’s impossible to define which overload to use.

Usage of Null

Null is often used as an uninitialized pointer with the purpose of pointing to something later on. It’s a value used to indicate that the pointer is not pointing to any value in memory. It’s important to remember that null is not a value and is not pointing towards any data. Here’s an example of how null is used in C++.

char *p = nullptr; // Same as char *p = 0;
int *q = NULL; // Same as int *q = 0;

In the above example, we have initialized two pointers p and q. Both p and q are null pointers, meaning that they are not pointing towards any objects.

When to Use Nullptr or Null

Nullptr and null should be used appropriately based on their functions.

Use nullptr:

– When initializing in code an empty or null pointer.
– While overloading functions where you don’t want any confusion.
– When the code requires a constant expression.

Use Null:

– When defining uninitialized pointers.
– When checking for null pointers.

Why is Nullptr Safer?

One of the significant advantages of using nullptr over null is that it’s safer. Assigning null to non-pointer variables will cause errors and crashes during runtime. Nullptr, on the other hand, is a strongly-typed pointer, and when attempted to be assigned to non-pointer variables, it throws an error during the compile stage.

When Should You Use Nullptr or Nullptr in Your Code?

There isn’t a clear-cut rule on when to use nullptr or null, but several pointers can guide their use.

– Always use nullptr in your code because it’s safer than null. It detects errors during compile-time rather than during runtime, making it easier for programmers to debug their code.
– If you are using the C++11 standard, always go for nullptr when initializing empty pointers. It’s easier to use and prevents confusions when using overloaded functions.


To summarise, both nullptr and null can be used to initialize a pointer whose value is unknown. Nullptr was introduced in C++11 and provides an explicit and safer way of initializing null pointers. Null, on the other hand, has been a part of C++ for a long time and can be used to define uninitialized pointers.

It’s always recommended to use nullptr in your code whenever possible, to avoid runtime errors caused by assigning null values to non-pointer types. Nullptr is also useful when dealing with overloaded functions where different data types are involved. Ensure that your code is correctly optimized so that it’s not tricky for everyone to understand.