1. 時間戳轉成格式化字串

直接利用函式os.date()將時間戳轉化成格式化字串.
```
local timestamp = 1561636137;
local strDate = os.date("%Y/%m/%d %H:%M:%S", timestamp)
print("strDate = ", strDate);
```
輸出: strDate = 	2019/06/27 19:48:57
注意'%Y', Y是大寫, 如果是小寫的話則輸出為:
輸出: strDate = 	19/06/27 19:48:57

2. 字串轉化成時間戳

通過string.find的模式匹配, 解析子串.
```
local strDate = "2019/06/27 19:48:57"
local _, _, y, m, d, hour, min, sec = string.find(strDate, "(%d+)/(%d+)/(%d+)%s*(%d+):(%d+):(%d+)");

print(y, m, d, hour, min, sec);
```
輸出: 2019	06	27	19	48	57
這裡已經將'y, m, d, hour, min, sec'從strDate中分離出來了, 接下來轉化為時間戳.完整程式碼:
```
--分離字串
local strDate = "2019/06/27 19:48:57"
local _, _, y, m, d, _hour, _min, _sec = string.find(strDate, "(%d+)/(%d+)/(%d+)%s*(%d+):(%d+):(%d+)");

print(y);
print(m);
print(d);
print(_hour);
print(_min);
print(_sec);

--轉化為時間戳
local timestamp = os.time({year=y, month = m, day = d, hour = _hour, min = _min, sec = _sec});
print("timestamp = ", timestamp);
```
輸出:
2019
06
27
19
48
57
timestamp =