c# - BinaryWriter 覆盖现有文件 c#

Question

要在我的袖珍电脑的内存上写一张图片，我使用以下代码:

pic = (byte[])myPicutureFromDatabase;
using (var fs = new BinaryWriter(new FileStream(filepath, FileMode.Append, FileAccess.Write)))
{
    fs.Write(pic);
    fs.Flush();
    continue;
}

我想问你，如果这个名字的文件已经存在，这个方法是否用新值覆盖文件，或者因为已经存在这个文件而什么都不做？
我需要覆盖该文件，以防该文件已经存在但具有旧值。

Answer 1

来自 MSDN文件模式.创建

Specifies that the operating system should create a new file. If the file already exists, it will be overwritten. This requires FileIOPermissionAccess.Write permission. FileMode.Create is equivalent to requesting that if the file does not exist, use CreateNew; otherwise, use Truncate. If the file already exists but is a hidden file, an UnauthorizedAccessException exception is thrown.

凡是 FileMode.Append

Opens the file if it exists and seeks to the end of the file, or creates a new file. This requires FileIOPermissionAccess.Append permission. FileMode.Append can be used only in conjunction with FileAccess.Write. Trying to seek to a position before the end of the file throws an IOException exception, and any attempt to read fails and throws a NotSupportedException exception.

所以，你应该使用这个

pic = (byte[])myPicutureFromDatabase;
using (var fs = new BinaryWriter(new FileStream(filepath, FileMode.Create, FileAccess.Write)))
       {
          fs.Write(pic);
          fs.Flush();
          continue;
        }