How to Convert Base64 string to Byte Array using C#


In this article, I will explain you how to convert Base64 string to Byte Array using C#.

1) When the image upload button clicked, that particular image file is read into a Byte Array with the help of BinaryReader class Object.

2) Now that Byte Array is converted into Base64 string using Convert.ToBase64String method.

3) Now to save Base64 encoded string as Image File, Base64 string is converted back to Byte Array with the help of Convert.FromBase64String function.

4) Lastly, the Byte Array save to your folder as a file using WriteAllBytes method.

protected void btnUpload_Click(object sender, EventArgs e)
    //Convert Image File to Base64 Encoded string
    //Read the uploaded image file using BinaryReader and convert it to Byte Array.

    BinaryReader br = new BinaryReader(FileUpload1.PostedFile.InputStream);
    byte[] bytes = br.ReadBytes((int)FileUpload1.PostedFile.InputStream.Length);
    //Convert the Byte Array to Base64 Encoded string.
    string base64String = Convert.ToBase64String(bytes, 0, bytes.Length);
    //Save Base64 Encoded string as Image File
    //Convert Base64 Encoded string to Byte Array.
    byte[] imageBytes = Convert.FromBase64String(base64String);
    //Save the Byte Array as Image File.
    string filePath = Server.MapPath("~/Images/" + Path.GetFileName(FileUpload1.PostedFile.FileName));
    File.WriteAllBytes(filePath, imageBytes);



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