What is union and structure?

A structure contains an ordered group of data objects. Unlike the elements of an array, the data objects within a structure can have varied data types. Each data object in a structure is a member or field. A union is an object similar to a structure except that all of its members start at the same location in memory .

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What are unions in C++?

In C++17 and later, the std::variant class is a type-safe alternative for a union. A union is a user-defined type in which all members share the same memory location . This definition means that at any given time, a union can contain no more than one object from its list of members.

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What is the declaration of structure?

A “structure declaration” names a type and specifies a sequence of variable values (called “members” or “fields” of the structure) that can have different types . An optional identifier, called a “tag,” gives the name of the structure type and can be used in subsequent references to the structure type.

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