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    • ๐ŸกVector [ArrayList]
      • Custom vector, part 1
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      • std::vector
    • โ™ป๏ธUnion
      • Type Punning
      • Type Punning, part 2
      • Type Punning, part 3
      • Union, part 1
      • Union, Part 2
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  1. Memory

Union

In C++, a union is a special class type that allows you to store different data types in the same memory location. Here's a concise explanation of unions and their uses:

Definition: A union is a user-defined type where all members share the same memory location.

Key characteristics:

  1. Only one member can hold a value at any given time.

  2. The size of a union is determined by its largest member.

Main uses:

  1. Memory optimisation: When you need to store different types of data, but never simultaneously, unions can save memory.

  2. Type punning: Unions allow reinterpreting the same data as different types, though this can lead to undefined behaviour if not done carefully.

  3. Interfacing with hardware: Unions are useful when working with low-level memory or hardware registers that can have multiple interpretations.

union Punner {
    float f;
    int i;
};

Punner p;
p.f = 3.14f;
int bits = p.i;  // Access float's bit pattern as an int
Previousstd::vectorNextType Punning

Last updated 8 months ago

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