C#•2y ago

✅ Whenever I read from a file, do I need to close the file if I want to read from it again?

I want to read from a file to get the number of names within the file so I can create an array with a correct number of elements. I'm wondering if it's okay for me to not close the file before determining that number of names.

// Open the file and get a StreamReader object.
                inputFile = File.OpenText("D:\\Projects\\Chapter7\\Ch7-BinarySearch\\Ch7-BinarySearch\\Names.txt");

                //getting the total number of names within the file
                while (!inputFile.EndOfStream)
                    index++;

                //do I need to close the file and reopen it to prevent an error in the next while loop here?

                // While we're not at the end of the array and not at the end of the file, Read the file's contents into the array.
 
int counter = 0;
                while (counter < index && !inputFile.EndOfStream)
                {
                    namesArray[counter] = inputFile.ReadLine();
                    counter++;
                }

                // Close the file.
                inputFile.Close();

// Open the file and get a StreamReader object.
                inputFile = File.OpenText("D:\\Projects\\Chapter7\\Ch7-BinarySearch\\Ch7-BinarySearch\\Names.txt");

                //getting the total number of names within the file
                while (!inputFile.EndOfStream)
                    index++;

                //do I need to close the file and reopen it to prevent an error in the next while loop here?

                // While we're not at the end of the array and not at the end of the file, Read the file's contents into the array.
 
int counter = 0;
                while (counter < index && !inputFile.EndOfStream)
                {
                    namesArray[counter] = inputFile.ReadLine();
                    counter++;
                }

                // Close the file.
                inputFile.Close();

12 Replies

Grin•2y ago

I need to clean up that code I'm just curious if you need to close a file if you want to read from the start of the file twice

phaseshift•2y ago

If you have a stream I bet you can seek back to the beginning. I'm wondering why you don't just File.ReadAllLines though

Grin•2y ago

My book hasn't covered File.ReadAllLines How would I include that in my code?

hiyosilver•2y ago

ReadAllLines returns a string array. You could assign it to namesArray directly rather than going line by line.

Grin•2y ago

I get an error when I try that

// Open the file and get a StreamReader object.
                inputFile = File.OpenText("D:\\Projects\\Chapter7\\Ch7-BinarySearch\\Ch7-BinarySearch\\Names.txt");

                string[] readText = File.ReadAllLines(inputFile);

// Open the file and get a StreamReader object.
                inputFile = File.OpenText("D:\\Projects\\Chapter7\\Ch7-BinarySearch\\Ch7-BinarySearch\\Names.txt");

                string[] readText = File.ReadAllLines(inputFile);

at the inputFile I get an error

hiyosilver•2y ago

What error? ReadAllLines takes a file path directly.

mtreit•2y ago

Probably that it's held in use because of the first line... Er... Wait... Passing the stream to ReadAllLines doesn't make any sense...

Unknown User•2y ago

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mtreit•2y ago

I believe that code will not even compile.

Unknown User•2y ago

Message Not Public

Grin•2y ago

I was just learning about binary searches in the end. But I would like to understand ReadAllLines, but I'll make a new project and continue testing for it there. I'm gonna close this for now

Accord•2y ago

Closed!

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✅ Whenever I read from a file, do I need to close the file if I want to read from it again?