Is file empty check

Question

How do I check if a file is empty in C#?

I need something like:

if (file is empty)
{
    // do stuff
}

else
{
    // do other stuff
}

Answer 1

Use FileInfo.Length:

if( new FileInfo( "file" ).Length == 0 )
{
  // empty
}

Check the Exists property to find out, if the file exists at all.

Answer 2

FileInfo.Length would not work in all cases, especially for text files. If you have a text file that used to have some content and now is cleared, the length may still not be 0 as the byte order mark may still retain.

You can reproduce the problem by creating a text file, adding some Unicode text to it, saving it, and then clearing the text and saving the file again.

Now FileInfo.Length will show a size that is not zero.

A solution for this is to check for Length < 6, based on the max size possible for byte order mark. If your file can contain single byte or a few bytes, then do the read on the file if Length < 6 and check for read size == 0.

public static bool IsTextFileEmpty(string fileName)
{
    var info = new FileInfo(fileName);
    if (info.Length == 0)
        return true;

    // only if your use case can involve files with 1 or a few bytes of content.
    if (info.Length < 6)
    {
        var content = File.ReadAllText(fileName);   
        return content.Length == 0;
    }
    return false;
}

Answer 3

The problem here is that the file system is volatile. Consider:

if (new FileInfo(name).Length > 0)
{  //another process or the user changes or even deletes the file right here

    // More code that assumes and existing, empty file
}
else
{


}

This can and does happen. Generally, the way you need to handle file-io scenarios is to re-think the process to use exceptions blocks, and then put your development time into writing good exception handlers.

Answer 4

if (!File.Exists(FILE_NAME))
{
    Console.WriteLine("{0} does not exist.", FILE_NAME);
    return;
}

if (new FileInfo(FILE_NAME).Length == 0)  
{  
    Console.WriteLine("{0} is empty", FILE_NAME);
    return;
} 

Answer 5

I've found that checking the FileInfo.Length field doesn't always work for certain files. For instance, and empty .pkgdef file has a length of 3. Therefore, I had to actually read all the contents of the file and return whether that was equal to empty string.

Answer 6

This is how I solved the problem. It will check if the file exists first then check the length. I'd consider a non-existent file to be effectively empty.

var info = new FileInfo(filename);
if ((!info.Exists) || info.Length == 0)
{
    // file is empty or non-existant    
}

Answer 7

In addition to answer of @tanascius, you can use

try
{
    if (new FileInfo("your.file").Length == 0)
    {
        //Write into file, i guess    
    }
} 
catch (FileNotFoundException e) 
{
    //Do anything with exception
}

And it will do it only if file exists, in catch statement you could create file, and run code agin.

Answer 8

What if file contains space? FileInfo("file").Length is equal to 2.
But I think that file is also empty (does not have any content except spaces (or line breaks)).

I used something like this, but does anybody have better idea?
May help to someone.

string file = "file.csv";
var fi = new FileInfo(file);
if (fi.Length == 0 || 
    (fi.Length < 100000 
     && !File.ReadAllLines(file)
        .Where(l => !String.IsNullOrEmpty(l.Trim())).Any()))
{
    //empty file
}

Answer 9

You can use this function if your file exists and is always copied to your debug/release directory.

/// <summary>
/// Include a '/' before your filename, and ensure you include the file extension, ex. "/myFile.txt"
/// </summary>
/// <param name="filename"></param>
/// <returns>True if it is empty, false if it is not empty</returns>
private Boolean CheckIfFileIsEmpty(string filename)
{
    var fileToTest = new FileInfo(Environment.CurrentDirectory + filename);
    return fileToTest.Length == 0;
}