Lua 中 table.sort 的比较函数

对 table.sort 的比较函数的理解不到位，结果把我害惨了T T

 

Lua 5.1 手册里是这么写的：

 

table.sort (table [, comp])

 

Sorts table elements in a given order, in-place, from table[1] to table[n], where n is the length of the table. If comp is given, then it must be a function that receives two table elements, and returns true when the first is less than the second (so that not comp(a[i+1],a[i]) will be true after the sort). If comp is not given, then the standard Lua operator < is used instead.

 

The sort algorithm is not stable; that is, elements considered equal by the given order may have their relative positions changed by the sort.

 

文中说：returns true when the first is less than the second

 

那如果两个参数相等应该返回什么？false！

 

关键就是这个，必须返回 false，否则排序的结果不正确。