【入门夯实】字符统计：频次表的gmatch一行写法

local s = "传奇传奇再传奇"
-- 按字节循环统计，切出来的是半个"传"字
for i = 1, #s do
    print(string.sub(s, i, i))
end

local s = "传奇传奇再传奇"
local count = {}
for ch in string.gmatch(s, "[\128-\255][\128-\191]*") do
    count[ch] = (count[ch] or 0) + 1
end
for ch, c in pairs(count) do
    print(ch, c)
end

local function countChar(s, ch)
    local n = 0
    for c in string.gmatch(s, "%" .. ch) do
        n = n + 1
    end
    return n
end
print(countChar("a,b,c", ","))