string - 如何在 Lua 中实现 string.rfind

Question

在 Lua 中只有string.find，但有时string.rfind需要。例如，解析目录和文件路径，如：

fullpath = "c:/abc/def/test.lua"
pos = string.rfind(fullpath,'/')
dir = string.sub(fullpath,pos)

怎么写这样的string.rfind？

Answer 1

You can use string.match:

fullpath = "c:/abc/def/test.lua"
dir = string.match(fullpath, ".*/")
file = string.match(fullpath, ".*/(.*)")

Here in the pattern, .* is greedy, so that it will match as much as it can before it matches /

UPDATE:

As @Egor Skriptunoff points out, this is better:

dir, file = fullpath:match'(.*/)(.*)'

Answer 2

Yu & Egor 的回答很有效。使用 find 的另一种可能性是反转字符串：

pos = #s - s:reverse():find("/") + 1