一个非常方便的log到文件的函数.我们通常需要在程序中记录一些东西到文件中,但是又不喜欢写很多打开,关闭文件等操作才能写.使用这个函数,可以非常方便的实现log功能.现在它已经成为我的标准log例程了.-A very convenient log to file function. We usually required in the procedure record something to a file, but do not like to write a lot of open, shut down operations in order to write documents. Use this function, can easily realize the log function. Now it has become my standard routine of the log.