Convert File to Byte Array In C#


In this article, let us see how to convert a file content to a byte array, restore the original content from the byte array, and display it in its original file formats such as pdf, doc, xls, rtf, jpeg, png, etc.

Convert a file content to a byte array

Step 1. Create an ASP.Net application and add a class Document.

public class Document  
    public int DocId { get; set; }  
    public string DocName { get; set; }  
    public byte[] DocContent { get; set; }  

Step 2. Create a format doc/pdf/rtf file and convert the file content to a ByteArray using the following method. Then create an object of type Document and assign the Docname and DocContent property values from the filename and filecontent.

public Document FileToByteArray(string fileName)  
    byte[] fileContent = null;  
    System.IO.FileStream fs = new System.IO.FileStream(fileName, System.IO.FileMode.Open, System.IO.FileAccess.Read);  
    System.IO.BinaryReader binaryReader = new System.IO.BinaryReader(fs);  
    long byteLength = new System.IO.FileInfo(fileName).Length;  
    fileContent = binaryReader.ReadBytes((Int32)byteLength);  
    Document = new Document();  
    Document.DocName = fileName;  
    Document.DocContent = fileContent;  
    return Document;  

Convert a byte array to file content

Step 3. Now we need to revert the byte array to the file content and display it to the user with download options. For that, I am using another method, ShowDocument, as below.

private void ShowDocument(string fileName, byte[] fileContent)  
    //Split the string by character . to get file extension type  
    string[] stringParts = fileName.Split(new char[] { '.' });  
    string strType = stringParts[1];  
    Response.AddHeader("content-disposition", "attachment; filename=" + fileName);  
    //Set the content type as file extension type  
    Response.ContentType = strType;  
    //Write the file content  

Step 4. In the page_load event, I have the following code: read the contents from the file and convert it to a ByteArray using the FileToByteArray method, and convert it back to content using the ShowDocument method.

protected void Page_Load(object sender, EventArgs e)  
    FileToByteArray("C:\\Users\\santhosh.kumar\\Documents\\Test for rht format.rtf");  
    ShowDocument(Document.DocName, Document.DocContent);  


This article taught us how to convert files to Byte Arrays and Byte Arrays to Files. For the complete source code, please find the attached solution. 

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