最近遇到的一個bug，根據條件搜索出來的數據，用PHPExcel導出Excel，很奇葩的問題是：只有某一天的數據導出來報錯：找不到文件...
百思不得其解，各個步驟數據都獲取到了，可以打印出來，沒有毛病，後來用fiddler監聽，發現報了一個500的錯誤：PHP Fatal error: Uncaught exception 'PHPExcel_Calculation_Exception' ...
查了一波，大多是說導出的數據中有特殊符號 “=” 導致Excel把等號後面的當成公式處理，所以出錯
可是，問題是數據太大，這個“=”也不好找
在stack overflow上找到了答案：引用一下
I'm guessing that one of the values retrieved from your database begins with an = sign, in which case PHPExcel will "guess" that it's supposed to be a formula and store it as such.
If you have values that begin with an = that aren't formulae, then you need to tell PHPExcel that it is a string and that it should be stored as such.
This behaviour is defined in the default cell binder (PHPExcel/Cell/DefaultValueBinder.php).
If you want to force PHPExcel to store these values as strings, then you can use the setCellValueExplicit() method (which defaults to enforcing a string)
Or you can write a custom value binder and apply that instead of the default value binder
用setCellValueExplicit()把所有的輸出到Excel表格的數據強制轉爲字符串，問題就解決了
馬克一下