CODEWITHSUNDEEP
c#.netforeachunassigned-variable
sebastian
sebastian

Reputation: 13

c# foreach loop access variable

I have the following problem: i have a string variable, which has to store a filepath. In a foreach loop i go through all files in a certain directory and im looking for the oldest, which is saved in that string variable. When the loop is finished i try to delete that file, but i get an error: Use of an unassigned local variable.

Here is the code:

DateTime min = DateTime.Now;
string[] fileNames = Directory.GetFiles(somePath);
string fileDelete;
int countFiles = fileNames.Length;
if (countfiles > 5)
{
    foreach (string someFile in fileNames)
    {
        FileInfo infoFile = new FileInfo(someFile);
        if (infoFile.CreationTime <= min)
        {
            min = infoFile.CreationTime;
            fileDelete = someFile;
        }   
    }
    File.Delete(fileDelete);
}

it says that the string fileDelete in File.Delete(fileDelete) has no value, but the fun thin is, when i give it a value at the beginning just like that:

string fileDelete = "blabla";

it works perfectly fine. This is just a snipped of the method in case you are wondering

Upvotes: 1

Views: 1902

Answers (5)

Suvidha
Suvidha

Reputation: 72

Use this

DateTime min = DateTime.Now;
string[] fileNames = Directory.GetFiles(somePath);
string fileDelete;
int countFiles = fileNames.Length;
if (countfiles > 5)
{
    foreach (string someFile in fileNames)
    {
        FileInfo infoFile = new FileInfo(someFile);
        if (infoFile.CreationTime <= min)
        {
            min = infoFile.CreationTime;
            fileDelete = someFile;
            File.Delete(fileDelete);
        }   
    }

}

Upvotes: 0

Georgios Tsaprazlis
Georgios Tsaprazlis

Reputation: 463

You must initialize your variable. see at Why compile error "Use of unassigned local variable"?

Upvotes: 0

Andrey Korneyev
Andrey Korneyev

Reputation: 26846

It works exactly as intended.

In C# local variables are not initialised automatically at declaration.

You're not assinging any value to the fileDelete when declaring it and assigning it only under some condition in your loop.

But you're trying to use its value outside this condition in loop, thus compiler can't deduce - will fileDelete has some value at runtime or not (if code under condition will not be executed - then fileDelete will has no value).

Thus compiler generates this error.

Upvotes: 1

Serve Laurijssen
Serve Laurijssen

Reputation: 9733

in C# you have to initialise variables, otherwise you could pass garbage values to File.Delete.

I recommend using 

string fileDelete = null; // or ""

and later check for that.

if (!string.IsNullOrEmpty(fileDelete))
{
  File.Delete(fileDelete);
}

Upvotes: 3

Kapol
Kapol

Reputation: 6463

Imagine this scenario:

  • countFiles > 5 is True
  • infoFile for someFile is bigger than min

What value will fileDelete have when passed to File.Delete?

Answer: In such scenario fileDelete will be uninitialized, thus the error message.

Upvotes: 0

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