计算机中的「魔数」（magic number）

摘自wikipedia：https://en.wikipedia.org/wiki/Magic_number_%28programming%29#Examples

In computer programming, the term magic number has multiple meanings. It could refer to one or more of the following:

A constant numerical or text value used to identify a file format or protocol; for files, see List of file signatures
Distinctive unique values that are unlikely to be mistaken for other meanings (e.g., Globally Unique Identifiers)
Unique values with unexplained meaning or multiple occurrences which could (preferably) be replaced with named constants

例如BMP图片文件的前缀是“BM”，JPEG图片文件的前缀是“JFIF”，这些文件的前缀就算是Magic number，这是指上面的第一种情况。再如Linux系统使用的uImage压缩内核的前缀是：0x27051956，这个就是uImage的Magic number，属于上面说的后面两种情况。三种情况都有共同点，都是用来作为区别事物的，一般用于程序检测文件类型做对应的处理工作。

原文链接：https://blog.csdn.net/tq384998430/article/details/77866679