# Chapter10Structure of the main Function
In Section 2.9 you learned that all C programs begin with a function named main, which you can think of as a subroutine that is called by the operating system. In this chapter you will learn how the main function is organized (which is typical of all functions in C, and how you can call other functions from main. You will also learn how a function allocates memory for its own use while it is being executed. In Chapter 13 you will learn how to write functions that are called by main.