How to check if System.IO.File.Delete deleted a file successfully

Question

After removing a file using the system.io.file class:

System.IO.File.Delete(openedPdfs.path);

I need to run some code if the file was sucessfully deleted. As long as the method does not return any value, I am checking if the file exist after the delete method. If it still exist I supposed the operation had failed.

The problem is, the deletion method works fine, but there is a couple of seconds to the file to be deleted. The Exist function return true because at the time it is checking the file is there.

How can I verify for sure if the System.IO.File.Delete(openedPdfs.path); completed successfully?

Code:

FileInfo file = new FileInfo(openedPdfs.path);    
System.IO.File.Delete(openedPdfs.path);
if (file.Exists == false)
{ ... }
else 
{ ... }

Answer 1

As others have pointed out, the File.Delete method will throw an exception in case of failure.

What they omitted to say is that the exception will be thrown in almost all cases but not in all cases.

Specifically, the File.Delete method will not throw an exception if the file to be deleted did not happen to already exist.

---

• If we look at the Official Microsoft Documentation for System.IO.File.Delete,
• and if we skip past the list of exceptions thrown,
• and if we keep scrolling to go past the extensive code example to arrive at a "Remarks" section,
• and if the keep reading this section despite the trivialities that it mostly consists of, such as
  • "Specify a file name with any relative or absolute path"
  • and "Relative path information is interpreted as relative to the current working directory"
  • and "To obtain the current working directory, see GetCurrentDirectory"
• then we arrive at the following little gem, hidden among the noise:

If the file to be deleted does not exist, no exception is thrown.

In other words, this function has deliberately built-in silent failure.

Silent failure constitutes sabotage against the developer in virtually all cases.

Answer 2

Delete should throw an exception if the file wasn't deleted. Hence, your call to Exists is redundant.

Have a look at the documentation for Delete.

Answer 3

This is ancillary to Daniel A. White's answer: We can see the signature for the method is public static void Delete(string path). So clearly, you're not going to get feedback from the Delete call except by exception. But let's suppose you have a file that gets written or updated periodically by another process:

1. Your program successfully delete the file.
2. The other process recreates it immediately after the delete.
3. Your program tests for existence with file.Exists. There's a new file with the same name, so that returns true. You're technically going down the wrong path.

This exact scenario might not be true for the problem you're currently trying to solve, but checking to see if the Delete call threw an exception is much more robust than relying on your current implementation.

Answer 4

It won't throw exception if file doesn't exists. In case of error it will throw exception if it couldn't be deleted, check File.Delete

Answer 5

You can always use

 System.IO.File.Exists(path)

Although I agree with Daniel, if Delete does not throw exception you should be good.

Answer 6

From the comments and suggestions you should be able to use the following to acheive your desired result

try {
  FileInfo file = new FileInfo(openedPdfs.path);    
  System.IO.File.Delete(openedPdfs.path);
  // if no exception is thrown then you should assume all has gone well and put  
  // your file successfully deleted code here.
} catch /*(Specfic exceptions can be referenced here in separate catch blocks see Daniel A. White answer)*/ {
  // If something bad happened and the file was not deleted put handling code here
} finally {
  // if some action needs to be taken regardless of whether the file was successfully deleted or not put 
  // that code here
}

Answer 7

I discovered that if you use the FileInfo Delete() instance method that the FileInfo instance property Exists is not updated.
For example the following code will throw a file not found exception because the file has been deleted but the second if (output_file.Exists) still evaluates to true.

FileInfo output_file;
if (output_file.Exists) output_file.Delete();   

FileStream fs;
if (output_file.Exists)
{
     fs = new FileStream(fi.FullName, FileMode.Open, FileAccess.ReadWrite);
}
else
{
     fs = new FileStream(fi.FullName, FileMode.CreateNew, FileAccess.ReadWrite);
}

I found that creating a new FileInfo from the old one fixed the problem:

FileInfo output_file;
if (output_file.Exists)
{
    output_file.Delete();
    output_file = new FileInfo(output_file.FullName);      
}

FileStream fs;
if (output_file.Exists)
{
     fs = new FileStream(fi.FullName, FileMode.Open, FileAccess.ReadWrite);
}
else
{
     fs = new FileStream(fi.FullName, FileMode.CreateNew, FileAccess.ReadWrite);
}

Answer 8

private String del(String fileLocation) {

 if (File.Exists(@fileLocation)) {
  try {
   File.Delete(@fileLocation);
  } catch (Exception e) {
   return "File couldn't be deleted because: " + e.GetType().Name;
  }
 } else {
  return "File doesn't exist";
 }

 return "File successfully deleted";
}