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.
What is union and structure in C?
Union. 1. Definition. Structure is the container defined in C to store data variables of different type and also supports for the user defined variables storage . On other hand Union is also similar kind of container in C which can also holds the different type of variables along with the user defined variables.