函数是 C 中最常用的结构概念。它们应用于实现“自顶向下的”问题解决方法 — 即，将问题分解成越来越小的子问题，直到每个子问题都能够用代码表示。这对程序的模块化和文档记录有帮助。此外，由许多小函数组成的程序更易于调试。-C function is the most commonly used structural concept. They used to achieve the "top-down" solution to the problem- that is, the problem is divided into increasingly small son, until every child that the problems can be expressed using code. This modular and procedures to document any help. In addition, many small component of the process function more easily debug.