Summary

• A structure is a collection of one or more variables, possibly of different types, grouped together for convenient handling.
• Structures help to organize data because they allow a group of variables to be treated as a single unit.
• A structure declaration starts with the keyword struct, which introduces the declaration.
• The structure tag, which follows the keyword, is optional. It is only a label and not an actual structure in memory.
• The declaration then follows with a list of variables enclosed within curly braces. These variables are called members.
• Members can be accessed using the member access operator '.".
• The struct declaration defines a new datatype.
• Nested structures are nothing but structures within structures.
• The 'typedef" statement is used to define a new datatype.
• Pointers to structures are just like pointers to other variables.
• Members can be accessed through the pointer variable using the member access operator '- >".
• Structures may be passed to functions either by value or by reference.
• A union is a variable that may hold objects of different types at different times.
• A union declaration is similar to a structure declaration.