Write/Read Text Files (C#)

Question

I wasn't 100% sure how to explain this in the title or how to search it up, so sorry if this has been post before. What I'm trying to do is read and write a file, for example I would do:

WriteToFile(key + "=" + value);

And in the text file it would say something like:

AKey=AValue

I was able to get that fairly easily but I was wonder how exactly would I get code to find that 'key' and return its value. For example:

int integer = GetValue("AKey");

And the method GetValue would find the 'key', "AKey", and if it existed in the file, return the value.

First, read all the lines in, then for each line split the string using the = sign, which gives you two strings. Store these strings in a `Dictionary` and then you can do something like `myDictionary["AKey"]`. — Ron Beyer, Oct 16 '15 at 21:11
Since you're storing data in a custom format, you would need to write a custom parser to read data from that format. — David, Oct 16 '15 at 21:13
@Sam Say if I have a code saying `Save("myNumber", 1);` So It would be `Save(string name, int number);` and that would save to a text file as **myNumber=1**. And then I have another method that gets the value of _myNumber_, which would be something like this: `Get("myNumber")` (`Get(string name)`) and It would return the value so in this case, 1. — superhb, Oct 16 '15 at 21:17

Ron Beyer · Accepted Answer · 2015-10-16T21:20:22.590

For the sake of complete-ness, I'll expand on my comment, here is some example code of how you would accomplish this:

Dictionary<string, string> _keys = new Dictionary<string, string>();

private void ReadInKeyFile(string keyFileName)
{
    _keys.Clear();

    string[] lines = System.IO.File.ReadAllLines(keyFileName);

    foreach (string line in lines)
    {
        string[] keyval = line.Split('=');
        _keys.Add(keyval[0], keyval[1]);
    }
}

private string GetValue(string key)
{
    string retVal = string.Empty;
    _keys.TryGetValue(key, out retVal);
    return retVal;
}

The Dictionary<string, string> holds the key/value pairs that are read in from the file, so when you want to refresh it, you would call the ReadInKeyFile function with the file name. You can then use GetValue to get the value for a particular key (or String.Empty if the key is not found).

There are some obvious checks that I'm missing in the code above (file doesn't exist, line doesn't contain a =, etc), but it gets you 90% of the way there.

Edit

Here is some extensions to that for adding new keys and writing it out to a file:

private void SaveKeysToFile(string keyFileName)
{
    StringBuilder sb = new StringBuilder();
    _keys.ToList().ForEach(kvp => 
       sb.AppendLine(string.Format("{0}={1}", kvp.Key, kvp.Value)));
    System.IO.File.WriteAllText(keyFileName, sb.ToString());
}

private void AddValue(string key, string value)
{
    _keys[key] = value;
}

The SaveToFile method converts the dictionary to the file format you use, and the AddValue adds a key and value (or changes the existing key if it already exists).

@DourHighArch Yes, of course, it would have to be escaped, but again, thats part of the 10% I leave up to the OP. It would "work" (as in not break) but it would give an unexpected result. It has the same problem if the key contains an = sign as well. — Ron Beyer, Oct 16 '15 at 21:22
So I recreated what you have done here to test it out. It seems that it isn't writing to file. Do you know what could be possibly causing this? — superhb, Oct 16 '15 at 21:45
Nevermind, I got it to write to the file. Thank you for the help! — superhb, Oct 16 '15 at 21:56

Write/Read Text Files (C#)

1 Answers1