https://DevOpsCloud.io -- Cloud Monk Losang Jinpa, Ph.D., MCSE/MCT, GitOps DevOps Engineer

See also Null References - The Billion Dollar Mistake by Tony Hoare, Tony Hoare, Null (SQL), Null reference, Null pointer, Null pointer exception, Nullable type, Null-Safety, Null-Safety

TLDR: A null pointer is a pointer in programming that does not point to any valid memory location or object. This concept, introduced in early programming languages like C in the 1970s, serves as a way to indicate the absence of a value or reference. However, improper handling of null pointers can lead to null pointer exceptions, causing runtime errors or application crashes.

https://en.wikipedia.org/wiki/Null_pointer

A null pointer is often used as a sentinel value to indicate “no object” or “no data” in scenarios like uninitialized variables or when an object is explicitly set to null. For example, in C, the `NULL` macro is used to represent a null pointer, while in Java or C Sharp, the keyword `null` serves the same purpose. Attempting to dereference a null pointer leads to undefined behavior in C and CPP or throws a runtime exception in managed languages like Java.

https://en.cppreference.com/w/cpp/utility/nullptr

Languages like Kotlin and Swift have addressed the challenges of null pointers by introducing null-safety features. In these languages, nullable and non-nullable types are explicitly defined, and the compiler enforces proper handling of null values. For instance, Kotlin's safe call operator (`?.`) prevents dereferencing nulls, significantly reducing the occurrence of null pointer issues.

https://kotlinlang.org/docs/null-safety.html

To mitigate the risks associated with null pointers, developers use defensive programming practices, such as null checks, default initializations, and static analysis tools like SonarQube or FindBugs. These tools scan codebases to identify potential null pointer exceptions and provide recommendations for safer alternatives, ensuring robust and reliable software systems.

https://www.sonarsource.com/products/sonarqube/