What does the `sizeof` operator do in C?

The sizeof operator in C is used to determine the size, in bytes, of a variable or data type. This is crucial for memory management and for understanding how much space different types of data will occupy. By using sizeof, you can obtain the size of primitive data types, such as int, float, or char, as well as user-defined data types like structures and arrays.

For example, if you use sizeof(int), it will return the number of bytes that an integer variable occupies in memory (commonly 4 bytes on many systems). This operator is evaluated at compile time, making it efficient for allocating memory dynamically when using functions like malloc or calloc.

Other answers provide different functionalities or purposes that are not related to what the sizeof operator does. Knowing how to properly use sizeof is important in programming for tasks such as memory allocation, debugging memory issues, and optimizing data structures.