typedef

根据现有类型定义新类型。它的语法反映了变量声明的语法。

/* Byte can be used wherever `unsigned char` is needed */
typedef unsigned char Byte;

/* Integer is the type used to declare an array consisting of a single int */
typedef int Integer[1];

/* NodeRef is a type used for pointers to a structure type with the tag "node" */
typedef struct node *NodeRef;

/* SigHandler is the function pointer type that gets passed to the signal function. */
typedef void (*SigHandler)(int);

虽然技术上不是存储类，但编译器会将其视为一个存储类，因为如果使用 typedef 关键字，则不允许使用其他任何存储类。

typedefs 很重要，不应该用 #define 宏代替。

typedef int newType; 
newType *ptr;        // ptr is pointer to variable of type 'newType' aka int

然而，

#define int newType
newType *ptr;        // Even though macros are exact replacements to words, this doesn't result to a pointer to variable of type 'newType' aka int