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c#memory-managementcollections
AmirAsadi
AmirAsadi

Reputation: 11

How is C# dictionary variable stored in memory?

Can anyone explain me how C# dictionary stored in memory? I do know that in C# memory management is done using heap and stack. But I really couldn't find a simple explanation on how memory is allocated when dictionary variable is created, is it created in stack frame or heap space?

Upvotes: 0

Views: 2510

Answers (2)

Emiliano Javier González
Emiliano Javier González

Reputation: 190

You can always check the Reference Source to see most of .NET implementations:

https://referencesource.microsoft.com/#mscorlib/system/collections/generic/dictionary.cs,d3599058f8d79be0

All of the entries in the Dictionary are structs for example, so, they are going to be handled like ones:

private struct Entry {
        public int hashCode;    // Lower 31 bits of hash code, -1 if unused
        public int next;        // Index of next entry, -1 if last
        public TKey key;           // Key of entry
        public TValue value;         // Value of entry
    }

Upvotes: 3

Marc Gravell
Marc Gravell

Reputation: 1062895

Firstly, you need to be very clear about what you're asking here; do you mean the dictionary? or the variable? because they're two completely different things.

The dictionary is an object on the managed heap.

The variable (the reference to the object on the managed heap) - could mean a "local", a "parameter", or a "field". Fields are wherever they are, and depends on the thing having the field (reference-type, vs non-boxed value-type (which may or may not itself be a field on something), vs boxed value-type). Could be heap or stack. Parameters and locals are usually on the stack, except when they are captured into a state context (async methods, anonymous methods / lambdas, iterator blocks, local functions), in which case they are actually treated as fields; and the "fields on what" depends on the exact context (local functions are structs, for example). Also note that the stack is an implementation detail!

But you probably mean "the dictionary itself", in which case: managed heap.

Upvotes: 4

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