The ones who are crazy enough to think they can change the world are the ones who do.- Steve Jobs
In C programming, structure is a collection of variables of different data types. These data types are under a common structure name. Refer For More C Structures
In C, a structure declaration can be placed inside another structure. Refer For More C Struct within Struct
An Enumeration is user defined data type. An enumerated type has a finite number of named values. It uses the keyword enum. Refer For More C Enumeration
Bit fields provides exact amount of bits required by the variable. Bit fields uses the memory very efficiently. The bits must be specified by non-negative(unsigned) integer type followed by a colon(:). Bit fields can also used as member in unions. Refer For More C Bitfields
Union is similar to the structures, it also contains number of members like structures. In C, union is identified by the keyword union The members of union share the same memory location within the computer, whereas each structure member has its own memory location within the computer. At any time of compilation, only one member of the union can reside in that memory location. The union require bytes that are equal to the bytes required by largest member within union. The union allocates fixed bytes. Thus, unions are used to conserve or save memory. Refer For More C Union
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