What does the `sizeof` operator do in C?

The sizeof operator in C is utilized to determine the size, in bytes, of a variable or a datatype. This operator provides a way to obtain the memory size associated with the specific data type or variable at compile time. For example, using sizeof(int) might return 4 on many platforms, indicating that an integer requires 4 bytes of memory. Similarly, if you apply sizeof to a variable like sizeof(myVariable), it will return the size of the variable's type in bytes.

This operator is essential for dynamic memory management and understanding the memory layout of data structures, as it helps programmers gauge how much space to allocate when using functions like malloc and to comprehend data structure sizes accurately.

Other choices include options that do not accurately reflect the functionality of sizeof: calculating the total number of variables in an array pertains more to array indexing and size manipulation rather than memory size, determining the total memory allocated to a program involves more extensive tools and runtime considerations, and counting lines in a file is unrelated to data types and memory size calculations.