first create a large file, and then point to 1.1 gigabytes of which add example,...

代码说明：

先创建一个大文件,然后一点一点往其中添加字节的例子,与网络下载工具创建文件的方式相同,非常适合初学者学习文件操作API-first create a large file, and then point to 1.1 gigabytes of which add example, and network tools to create documents downloaded in the same way, very suitable for beginners learning file manipulation API