GetValueOrDefault

GetValueOrDefault is a common method name used in programming libraries to obtain a stored value when present or a fallback default when it is not. It appears most often in the context of nullable value types and collection lookup helpers.

In .NET, Nullable<T>.GetValueOrDefault() returns the contained value when HasValue is true, otherwise it returns default(T). An overload accepting a user-specified default value allows callers to supply an alternative fallback. Because it never throws for missing values, it is safer than accessing Value, which throws InvalidOperationException if the nullable has no value.

Many frameworks and utility libraries also provide GetValueOrDefault variants for dictionaries or maps. These return the value associated with a key when found, or default(TValue) (or a supplied fallback) when the key is absent. Such helpers simplify code that would otherwise require explicit existence checks.

Typical uses include reading optional data without exception handling, supplying sensible defaults in configuration parsing, and simplifying lookup patterns. Pitfalls include unintentionally using a type’s default (for example 0 for numeric types or null for reference types) when a different sentinel would be more appropriate; in such cases the overload accepting a custom default should be used. Conceptually, the method mirrors other idioms like the null-coalescing operator or optional-or-else functions in other languages, but its exact name and overloads vary by platform and library.