c# - 出现错误：无法从“对象”转换为“字符串”

Question

我有以下小功能：

public Image AddImage(Stream stream)
{
    return AddImage(stream as object);
}

我总是收到错误Can not convert from 'object' to 'string'

Stream是类型System.IO.Stream

怎么了？如何解决这个问题？

Answer 1

从您的更新到问题，您有两个AddImage. 一个接受 a Stream，一个接受 a string。

您正在尝试调用AddImage(object)，但没有匹配的重载。编译器告诉您不能将对象发送到AddImage(string blah)方法。

Answer 2

你为什么不只创建一个函数

public Image AddImage(Stream stream, string filename)
    {
        string contentType = "";
        Image image; 

        // The extension this file has will be taken to be its format.
        switch (Path.GetExtension(filename))
        {
            case ".tiff": contentType = "image/tif"; break;
            case ".tif": contentType = "image/tif"; break;
            case ".png": contentType = "image/png"; break;
            case ".bmp": contentType = "image/png"; break;
            case ".gif": contentType = "image/gif"; break;
            case ".jpg": contentType = "image/jpg"; break;
            case ".jpeg": contentType = "image/jpeg"; break;
            default: contentType = "image/jpg"; break;
        }

        //What you do in the third function;

       return image;
    }