What is union explain with example?

A union is a user-defined type similar to structs in C except for one key difference . Structures allocate enough space to store all their members, whereas unions can only hold one member value at a time.

The primary use of a union is allowing access to a common location by different data types , for example hardware input/output access, bitfield and word sharing, or type punning. Unions can also provide low-level polymorphism.

That is the main difference between structure union and enum in C. … Structure and union are two methods to store multiple variables of different types as a single variable . On the other hand, enum is a data type to declare a set of named constants. All these are user-defined data types.

A union is like a struct in that it generally has several fields , all of which are public by default. Unlike a struct, however, only one of the fields is used at any given time. In other words, it is a structure that allows the same storage space to be used to store values of different data types at different times.