What are the differences between structs and unions in C?

What are the differences between structs and unions in C?

Structs and unions are both user-defined data types in C, but they have key differences. A struct allocates separate memory for each of its members, while a union shares the same memory location for all its members.

Can you give an example of when to use a struct versus a union?

Sure! Use a struct when you need to store multiple attributes of an object, like a 'Person' with name and age. Use a union when you want to save memory and only need one of several possible values, like a 'Data' type that can be an int, float, or char.

What happens if I try to access a union member that wasn't the last one written to?

Accessing a union member that wasn't the last one written to can lead to undefined behavior, as the value may not be valid for that member. Always ensure you're accessing the correct member.

Are there any performance differences between using structs and unions?

Generally, structs may have a slight overhead due to separate memory allocation, while unions can be more memory-efficient. However, performance differences are usually negligible unless in a memory-constrained environment.