Lua 中 table.sort 的比較函數

對 table.sort 的比較函數的理解不到位，結果把我害慘了T T

 

Lua 5.1 手冊裡是這麼寫的：

 

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.

 

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

 

那如果兩個參數相等應該返回什嗎？false！

 

關鍵就是這個，必須返回 false，否則排序的結果不正確。