#import" xxx"之间的区别是什么？和#import< xxx>？
可能重复：
＃include< filename>之间有什么区别？和#include“ filename”？
写#import< filename.h>之间的区别和#import“ filename.h”即用尖括号和引号写出文件名？
这可能是一个愚蠢的问题。有什么区别 #import< QuartzCore / QuartzCore.h> 和 #importQuartzCore / QuartzCore.h？ （大于/小于双引号）
This might be a stupid question. What is the difference between #import <QuartzCore/QuartzCore.h> and #import "QuartzCore/QuartzCore.h"? (greater-than/less-than vs the double-quotes)
它们似乎都有效。
一般来说， #importQuartzCore / QuartzCore.h表格是找到我自己的标题，如果找不到它，则查找系统标题，< QuartzCore / QuartzCore.h> 表格是查找系统标题。从理论上讲，这些位置是编译器定义的，它们可以在给定的平台上以不同的方式实现，但我没有遇到过做任何不同的C编译器。
In general the #import "QuartzCore/QuartzCore.h" form is "find my very own header, if you can't find it look for a system header", and the <QuartzCore/QuartzCore.h> form is "find a system header". In theory the locations are compiler defined and they could be implemented differently on a given platform, but I haven't run into a C compiler that does anything different.