今天在困惑int和long的使用。

查到c语言中，int和long的字节数是和操作系统指针所占位数相等。

但c语言中说，long的长度永远大于或等于int

objective-c里，苹果的官方文档中总是推荐用NSInteger

它和int有什么区别呢，stackoverflow这帮大神给了答案。

原来在苹果的api实现中，NSInteger是一个封装，它会识别当前操作系统的位数，自动返回最大的类型。

定义的代码类似于下：

#if __LP64__ || TARGET_OS_EMBEDDED || TARGET_OS_IPHONE || TARGET_OS_WIN32 || NS_BUILD_32_LIKE_64

typedeflongNSInteger;

typedefunsignedlongNSUInteger;

#else

typedefintNSInteger;

typedefunsignedintNSUInteger;

#endif

You usually want to useNSIntegerwhen you don't know what kind of processor architecture your code might run on, so you may for some reason want the largest possibleinttype, which on 32 bit systems is just anint, while on a 64-bit system it's along.

From:http://blog.csdn.net/delphi090902/article/details/6967247