Here’s a comparison between structures and unions presented in a tabular format:
| Feature | Structures | Unions |
|---|---|---|
| Definition | Defined using the struct keyword followed by member variables enclosed in braces {}. | Defined using the union keyword followed by member variables enclosed in braces {}. |
| Memory Allocation | Each member has its own memory space. | All members share the same memory space. |
| Size | Size is equal to the sum of the sizes of its members. | Size is equal to the size of its largest member. |
| Accessing Members | Accessed using the dot . operator. | Accessed using the dot . operator or the arrow -> operator when working with pointers to unions. |
| Data Integrity | Modifying one member does not affect other members. | Modifying one member affects other members sharing the same memory space. |
| Use Cases | Useful for grouping related data of different types. | Useful for representing different interpretations of data in the same memory location. |
| Memory Efficiency | Less memory efficient if different members have different sizes. | More memory efficient when representing different data types in the same memory location. |
| Example | c struct Point { int x; int y; }; | c union MyUnion { int i; float f; char c; }; |
This table summarizes the key differences between structures and unions, helping to understand when to use each based on specific programming requirements.