What are the differences between structures and unions in C?

What are the differences between structures and unions in C?

In C, structures and unions are both used to group different data types, but they handle memory differently. A structure allocates enough memory to hold all its members, while a union allocates memory for the largest member only.

Can you give an example of when to use a structure over a union?

Sure! Use a structure when you need to store multiple attributes of an object, like a 'Person' with a name, age, and height. Use a union when you want to save memory and only need to store one of several possible values at a time.

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 memory may contain data from another member. It's important to keep track of which member is currently valid.

Are there any performance differences between using structures and unions?

Generally, structures may have a slight overhead due to their larger memory allocation, but the performance difference is usually negligible. The choice should be based on the specific use case rather than performance.