Reading/writing an INI file

Question

Is there any class in the .NET framework that can read/write standard .ini files:

[Section]
<keyname>=<value>
...

Delphi has the TIniFile component and I want to know if there is anything similar for C#?

Answer 1

Preface

Firstly, read this MSDN blog post on the limitations of INI files. If it suits your needs, read on.

This is a concise implementation I wrote, utilising the original Windows P/Invoke, so it is supported by all versions of Windows with .NET installed, (i.e. Windows 98 - Windows 11). I hereby release it into the public domain - you're free to use it commercially without attribution.

The tiny class

Add a new class called IniFile.cs to your project:

using System.IO;
using System.Reflection;
using System.Runtime.InteropServices;
using System.Text;

// Change this to match your program's normal namespace
namespace MyProg
{
    class IniFile   // revision 11
    {
        string Path;
        string EXE = Assembly.GetExecutingAssembly().GetName().Name;

        [DllImport("kernel32", CharSet = CharSet.Unicode)]
        static extern long WritePrivateProfileString(string Section, string Key, string Value, string FilePath);

        [DllImport("kernel32", CharSet = CharSet.Unicode)]
        static extern int GetPrivateProfileString(string Section, string Key, string Default, StringBuilder RetVal, int Size, string FilePath);

        public IniFile(string IniPath = null)
        {
            Path = new FileInfo(IniPath ?? EXE + ".ini").FullName;
        }

        public string Read(string Key, string Section = null)
        {
            var RetVal = new StringBuilder(255);
            GetPrivateProfileString(Section ?? EXE, Key, "", RetVal, 255, Path);
            return RetVal.ToString();
        }

        public void Write(string Key, string Value, string Section = null)
        {
            WritePrivateProfileString(Section ?? EXE, Key, Value, Path);
        }

        public void DeleteKey(string Key, string Section = null)
        {
            Write(Key, null, Section ?? EXE);
        }

        public void DeleteSection(string Section = null)
        {
            Write(null, null, Section ?? EXE);
        }

        public bool KeyExists(string Key, string Section = null)
        {
            return Read(Key, Section).Length > 0;
        }
    }
}

How to use it

Open the INI file in one of the 3 following ways:

// Creates or loads an INI file in the same directory as your executable
// named EXE.ini (where EXE is the name of your executable)
var MyIni = new IniFile();

// Or specify a specific name in the current dir
var MyIni = new IniFile("Settings.ini");

// Or specify a specific name in a specific dir
var MyIni = new IniFile(@"C:\Settings.ini");

You can write some values like so:

MyIni.Write("DefaultVolume", "100");
MyIni.Write("HomePage", "http://www.google.com");

To create a file like this:

[MyProg]
DefaultVolume=100
HomePage=http://www.google.com

To read the values out of the INI file:

var DefaultVolume = MyIni.Read("DefaultVolume");
var HomePage = MyIni.Read("HomePage");

Optionally, you can set [Section]'s:

MyIni.Write("DefaultVolume", "100", "Audio");
MyIni.Write("HomePage", "http://www.google.com", "Web");

To create a file like this:

[Audio]
DefaultVolume=100

[Web]
HomePage=http://www.google.com

You can also check for the existence of a key like so:

if(!MyIni.KeyExists("DefaultVolume", "Audio"))
{
    MyIni.Write("DefaultVolume", "100", "Audio");
}

You can delete a key like so:

MyIni.DeleteKey("DefaultVolume", "Audio");

You can also delete a whole section (including all keys) like so:

MyIni.DeleteSection("Web");

Please feel free to comment with any improvements!

Answer 2

The creators of the .NET framework want you to use XML-based config files, rather than INI files. So no, there is no built-in mechanism for reading them.

There are third party solutions available, though.

• INI handlers can be obtained as NuGet packages, such as INI Parser.
• You can write your own INI handler, which is the old-school, laborious way. It gives you more control over the implementation, which you can use for bad or good. See e.g. an INI file handling class using C#, P/Invoke and Win32.

Answer 3

This article on CodeProject "An INI file handling class using C#" should help.

The author created a C# class "Ini" which exposes two functions from KERNEL32.dll. These functions are: WritePrivateProfileString and GetPrivateProfileString. You will need two namespaces: System.Runtime.InteropServices and System.Text.

Steps to use the Ini class

In your project namespace definition add

using INI;

Create a INIFile like this

INIFile ini = new INIFile("C:\\test.ini");

Use IniWriteValue to write a new value to a specific key in a section or use IniReadValue to read a value FROM a key in a specific Section.

Note: if you're beginning from scratch, you could read this MSDN article: How to: Add Application Configuration Files to C# Projects. It's a better way for configuring your application.

Answer 4

I found this simple implementation:

http://bytes.com/topic/net/insights/797169-reading-parsing-ini-file-c

Works well for what I need.

Here is how you use it:

public class TestParser
{
    public static void Main()
    {
        IniParser parser = new IniParser(@"C:\test.ini");

        String newMessage;

        newMessage = parser.GetSetting("appsettings", "msgpart1");
        newMessage += parser.GetSetting("appsettings", "msgpart2");
        newMessage += parser.GetSetting("punctuation", "ex");

        //Returns "Hello World!"
        Console.WriteLine(newMessage);
        Console.ReadLine();
    }
}

Here is the code:

using System;
using System.IO;
using System.Collections;

public class IniParser
{
    private Hashtable keyPairs = new Hashtable();
    private String iniFilePath;

    private struct SectionPair
    {
        public String Section;
        public String Key;
    }

    /// <summary>
    /// Opens the INI file at the given path and enumerates the values in the IniParser.
    /// </summary>
    /// <param name="iniPath">Full path to INI file.</param>
    public IniParser(String iniPath)
    {
        TextReader iniFile = null;
        String strLine = null;
        String currentRoot = null;
        String[] keyPair = null;

        iniFilePath = iniPath;

        if (File.Exists(iniPath))
        {
            try
            {
                iniFile = new StreamReader(iniPath);

                strLine = iniFile.ReadLine();

                while (strLine != null)
                {
                    strLine = strLine.Trim().ToUpper();

                    if (strLine != "")
                    {
                        if (strLine.StartsWith("[") && strLine.EndsWith("]"))
                        {
                            currentRoot = strLine.Substring(1, strLine.Length - 2);
                        }
                        else
                        {
                            keyPair = strLine.Split(new char[] { '=' }, 2);

                            SectionPair sectionPair;
                            String value = null;

                            if (currentRoot == null)
                                currentRoot = "ROOT";

                            sectionPair.Section = currentRoot;
                            sectionPair.Key = keyPair[0];

                            if (keyPair.Length > 1)
                                value = keyPair[1];

                            keyPairs.Add(sectionPair, value);
                        }
                    }

                    strLine = iniFile.ReadLine();
                }

            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                if (iniFile != null)
                    iniFile.Close();
            }
        }
        else
            throw new FileNotFoundException("Unable to locate " + iniPath);

    }

    /// <summary>
    /// Returns the value for the given section, key pair.
    /// </summary>
    /// <param name="sectionName">Section name.</param>
    /// <param name="settingName">Key name.</param>
    public String GetSetting(String sectionName, String settingName)
    {
        SectionPair sectionPair;
        sectionPair.Section = sectionName.ToUpper();
        sectionPair.Key = settingName.ToUpper();

        return (String)keyPairs[sectionPair];
    }

    /// <summary>
    /// Enumerates all lines for given section.
    /// </summary>
    /// <param name="sectionName">Section to enum.</param>
    public String[] EnumSection(String sectionName)
    {
        ArrayList tmpArray = new ArrayList();

        foreach (SectionPair pair in keyPairs.Keys)
        {
            if (pair.Section == sectionName.ToUpper())
                tmpArray.Add(pair.Key);
        }

        return (String[])tmpArray.ToArray(typeof(String));
    }

    /// <summary>
    /// Adds or replaces a setting to the table to be saved.
    /// </summary>
    /// <param name="sectionName">Section to add under.</param>
    /// <param name="settingName">Key name to add.</param>
    /// <param name="settingValue">Value of key.</param>
    public void AddSetting(String sectionName, String settingName, String settingValue)
    {
        SectionPair sectionPair;
        sectionPair.Section = sectionName.ToUpper();
        sectionPair.Key = settingName.ToUpper();

        if (keyPairs.ContainsKey(sectionPair))
            keyPairs.Remove(sectionPair);

        keyPairs.Add(sectionPair, settingValue);
    }

    /// <summary>
    /// Adds or replaces a setting to the table to be saved with a null value.
    /// </summary>
    /// <param name="sectionName">Section to add under.</param>
    /// <param name="settingName">Key name to add.</param>
    public void AddSetting(String sectionName, String settingName)
    {
        AddSetting(sectionName, settingName, null);
    }

    /// <summary>
    /// Remove a setting.
    /// </summary>
    /// <param name="sectionName">Section to add under.</param>
    /// <param name="settingName">Key name to add.</param>
    public void DeleteSetting(String sectionName, String settingName)
    {
        SectionPair sectionPair;
        sectionPair.Section = sectionName.ToUpper();
        sectionPair.Key = settingName.ToUpper();

        if (keyPairs.ContainsKey(sectionPair))
            keyPairs.Remove(sectionPair);
    }

    /// <summary>
    /// Save settings to new file.
    /// </summary>
    /// <param name="newFilePath">New file path.</param>
    public void SaveSettings(String newFilePath)
    {
        ArrayList sections = new ArrayList();
        String tmpValue = "";
        String strToSave = "";

        foreach (SectionPair sectionPair in keyPairs.Keys)
        {
            if (!sections.Contains(sectionPair.Section))
                sections.Add(sectionPair.Section);
        }

        foreach (String section in sections)
        {
            strToSave += ("[" + section + "]\r\n");

            foreach (SectionPair sectionPair in keyPairs.Keys)
            {
                if (sectionPair.Section == section)
                {
                    tmpValue = (String)keyPairs[sectionPair];

                    if (tmpValue != null)
                        tmpValue = "=" + tmpValue;

                    strToSave += (sectionPair.Key + tmpValue + "\r\n");
                }
            }

            strToSave += "\r\n";
        }

        try
        {
            TextWriter tw = new StreamWriter(newFilePath);
            tw.Write(strToSave);
            tw.Close();
        }
        catch (Exception ex)
        {
            throw ex;
        }
    }

    /// <summary>
    /// Save settings back to ini file.
    /// </summary>
    public void SaveSettings()
    {
        SaveSettings(iniFilePath);
    }
}

Answer 5

The code in joerage's answer is inspiring.

Unfortunately, it changes the character casing of the keys and does not handle comments. So I wrote something that should be robust enough to read (only) very dirty INI files and allows to retrieve keys as they are.

It uses some LINQ, a nested case insensitive string dictionary to store sections, keys and values, and read the file in one go.

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;

class IniReader
{
    Dictionary<string, Dictionary<string, string>> ini = new Dictionary<string, Dictionary<string, string>>(StringComparer.InvariantCultureIgnoreCase);

    public IniReader(string file)
    {
        var txt = File.ReadAllText(file);

        Dictionary<string, string> currentSection = new Dictionary<string, string>(StringComparer.InvariantCultureIgnoreCase);

        ini[""] = currentSection;

        foreach(var line in txt.Split(new[]{"\n"}, StringSplitOptions.RemoveEmptyEntries)
                               .Where(t => !string.IsNullOrWhiteSpace(t))
                               .Select(t => t.Trim()))
        {
            if (line.StartsWith(";"))
                continue;

            if (line.StartsWith("[") && line.EndsWith("]"))
            {
                currentSection = new Dictionary<string, string>(StringComparer.InvariantCultureIgnoreCase);
                ini[line.Substring(1, line.LastIndexOf("]") - 1)] = currentSection;
                continue;
            }

            var idx = line.IndexOf("=");
            if (idx == -1)
                currentSection[line] = "";
            else
                currentSection[line.Substring(0, idx)] = line.Substring(idx + 1);
        }
    }

    public string GetValue(string key)
    {
        return GetValue(key, "", "");
    }

    public string GetValue(string key, string section)
    {
        return GetValue(key, section, "");
    }

    public string GetValue(string key, string section, string @default)
    {
        if (!ini.ContainsKey(section))
            return @default;

        if (!ini[section].ContainsKey(key))
            return @default;

        return ini[section][key];
    }

    public string[] GetKeys(string section)
    {
        if (!ini.ContainsKey(section))
            return new string[0];

        return ini[section].Keys.ToArray();
    }

    public string[] GetSections()
    {
        return ini.Keys.Where(t => t != "").ToArray();
    }
}

Answer 6

I want to introduce an IniParser library I've created completely in c#, so it contains no dependencies in any OS, which makes it Mono compatible. Open Source with MIT license -so it can be used in any code.

You can check out the source in GitHub, and it is also available as a NuGet package

It's heavily configurable, and really simple to use.

Sorry for the shameless plug but I hope it can be of help of anyone revisiting this answer.

Answer 7

If you only need read access and not write access and you are using the Microsoft.Extensions.Confiuration (comes bundled in by default with ASP.NET Core but works with regular programs too) you can use the NuGet package Microsoft.Extensions.Configuration.Ini to import ini files in to your configuration settings.

public Startup(IHostingEnvironment env)
{
    var builder = new ConfigurationBuilder()
        .SetBasePath(env.ContentRootPath)
        .AddIniFile("SomeConfig.ini", optional: false);
    Configuration = builder.Build();
}

Answer 8

PeanutButter.INI is a Nuget-packaged class for INI files manipulation. It supports read/write, including comments – your comments are preserved on write. It appears to be reasonably popular, is tested and easy to use. It's also totally free and open-source.

Disclaimer: I am the author of PeanutButter.INI.

Answer 9

If you want just a simple reader without sections and any other dlls here is simple solution:

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Tool
{
    public class Config
    {
        Dictionary <string, string> values;
        public Config (string path)
        {
            values = File.ReadLines(path)
            .Where(line => (!String.IsNullOrWhiteSpace(line) && !line.StartsWith("#")))
            .Select(line => line.Split(new char[] { '=' }, 2, 0))
            .ToDictionary(parts => parts[0].Trim(), parts => parts.Length>1?parts[1].Trim():null);
        }
        public string Value (string name, string value=null)
        {
            if (values!=null && values.ContainsKey(name))
            {
                return values[name];
            }
            return value;
        }
    }
}

Usage sample:

    file = new Tool.Config (Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().Location) + "\\config.ini");
    command = file.Value ("command");
    action = file.Value ("action");
    string value;
    //second parameter is default value if no key found with this name
    value = file.Value("debug","true");
    this.debug = (value.ToLower()=="true" || value== "1");
    value = file.Value("plain", "false");
    this.plain = (value.ToLower() == "true" || value == "1");

Config file content meanwhile (as you see supports # symbol for line comment):

#command to run
command = php

#default script
action = index.php

#debug mode
#debug = true

#plain text mode
#plain = false

#icon = favico.ico

Answer 10

Usually, when you create applications using C# and the .NET framework, you will not use INI files. It is more common to store settings in an XML-based configuration file or in the registry. However, if your software shares settings with a legacy application it may be easier to use its configuration file, rather than duplicating the information elsewhere.

The .NET framework does not support the use of INI files directly. However, you can use Windows API functions with Platform Invocation Services (P/Invoke) to write to and read from the files. In this link we create a class that represents INI files and uses Windows API functions to manipulate them. Please go through the following link.

Reading and Writing INI Files

Answer 11

Try this method:

public static Dictionary<string, string> ParseIniDataWithSections(string[] iniData)
{
    var dict = new Dictionary<string, string>();
    var rows = iniData.Where(t => 
        !String.IsNullOrEmpty(t.Trim()) && !t.StartsWith(";") && (t.Contains('[') || t.Contains('=')));
    if (rows == null || rows.Count() == 0) return dict;
    string section = "";
    foreach (string row in rows)
    {
        string rw = row.TrimStart();
        if (rw.StartsWith("["))
            section = rw.TrimStart('[').TrimEnd(']');
        else
        {
            int index = rw.IndexOf('=');
            dict[section + "-" + rw.Substring(0, index).Trim()] = rw.Substring(index+1).Trim().Trim('"');
        }
    }
    return dict;
}

It creates the dictionary where the key is "-". You can load it like this:

var dict = ParseIniDataWithSections(File.ReadAllLines(fileName));

Answer 12

I'm late to join the party, but I had the same issue today and I've written the following implementation:

using System.Text.RegularExpressions;

static bool match(this string str, string pat, out Match m) =>
    (m = Regex.Match(str, pat, RegexOptions.IgnoreCase)).Success;

static void Main()
{
    Dictionary<string, Dictionary<string, string>> ini = new Dictionary<string, Dictionary<string, string>>();
    string section = "";

    foreach (string line in File.ReadAllLines(.........)) // read from file
    {
        string ln = (line.Contains('#') ? line.Remove(line.IndexOf('#')) : line).Trim();

        if (ln.match(@"^[ \t]*\[(?<sec>[\w\-]+)\]", out Match m))
            section = m.Groups["sec"].ToString();
        else if (ln.match(@"^[ \t]*(?<prop>[\w\-]+)\=(?<val>.*)", out m))
        {
            if (!ini.ContainsKey(section))
                ini[section] = new Dictionary<string, string>();

            ini[section][m.Groups["prop"].ToString()] = m.Groups["val"].ToString();
        }
    }


    // access the ini file as follows:
    string content = ini["section"]["property"];
}

It must be noted, that this implementation does not handle sections or properties which are not found. To achieve this, you should extend the Dictionary<,>-class to handle unfound keys.

---

To serialize an instance of Dictionary<string, Dictionary<string, string>> to an .ini-file, I use the following code:

string targetpath = .........;
Dictionary<string, Dictionary<string, string>> ini = ........;
StringBuilder sb = new StringBuilder();

foreach (string section in ini.Keys)
{
    sb.AppendLine($"[{section}]");

    foreach (string property in ini[section].Keys)
        sb.AppendLine($"{property}={ini[section][property]");
}

File.WriteAllText(targetpath, sb.ToString());

Answer 13

There is an Ini Parser available in CommonLibrary.NET

This has various very convenient overloads for getting sections/values and is very light weight.

Answer 14

Here is my own version, using regular expressions. This code assumes that each section name is unique - if however this is not true - it makes sense to replace Dictionary with List. This function supports .ini file commenting, starting from ';' character. Section starts normally [section], and key value pairs also comes normally "key = value". Same assumption as for sections - key name is unique.

/// <summary>
/// Loads .ini file into dictionary.
/// </summary>
public static Dictionary<String, Dictionary<String, String>> loadIni(String file)
{
    Dictionary<String, Dictionary<String, String>> d = new Dictionary<string, Dictionary<string, string>>();

    String ini = File.ReadAllText(file);

    // Remove comments, preserve linefeeds, if end-user needs to count line number.
    ini = Regex.Replace(ini, @"^\s*;.*$", "", RegexOptions.Multiline);

    // Pick up all lines from first section to another section
    foreach (Match m in Regex.Matches(ini, "(^|[\r\n])\\[([^\r\n]*)\\][\r\n]+(.*?)(\\[([^\r\n]*)\\][\r\n]+|$)", RegexOptions.Singleline))
    {
        String sectionName = m.Groups[2].Value;
        Dictionary<String, String> lines = new Dictionary<String, String>();

        // Pick up "key = value" kind of syntax.
        foreach (Match l in Regex.Matches(ini, @"^\s*(.*?)\s*=\s*(.*?)\s*$", RegexOptions.Multiline))
        {
            String key = l.Groups[1].Value;
            String value = l.Groups[2].Value;

            // Open up quotation if any.
            value = Regex.Replace(value, "^\"(.*)\"$", "$1");

            if (!lines.ContainsKey(key))
                lines[key] = value;
        }

        if (!d.ContainsKey(sectionName))
            d[sectionName] = lines;
    }

    return d;
}

Answer 15

If you don't need bells and whistles (ie sections) here's a one liner:

List<(string, string)> ini = File.ReadLines(filename)
  .Select(s => {
     var spl = s.Split('=', 2);
     return spl.Length == 2 ? (spl[0], spl[1]) : (s, "");
   })
   .Select(vt => (vt.Item1.Trim(), vt.Item2.Trim()))
   .Where(vt => vt.Item1 != "")
   .ToList();

To write:

File.WriteAllLines(filename, ini.Select(vt => $"{vt.Item1}={vt.Item2}"));

(if you don't care about duplicates use .ToDictionary() instead of .ToList() for easier access)

Answer 16

Here is my class, works like a charm :

public static class IniFileManager
{


    [DllImport("kernel32")]
    private static extern long WritePrivateProfileString(string section,
        string key, string val, string filePath);
    [DllImport("kernel32")]
    private static extern int GetPrivateProfileString(string section,
             string key, string def, StringBuilder retVal,
        int size, string filePath);
    [DllImport("kernel32.dll")]
    private static extern int GetPrivateProfileSection(string lpAppName,
             byte[] lpszReturnBuffer, int nSize, string lpFileName);


    /// <summary>
    /// Write Data to the INI File
    /// </summary>
    /// <PARAM name="Section"></PARAM>
    /// Section name
    /// <PARAM name="Key"></PARAM>
    /// Key Name
    /// <PARAM name="Value"></PARAM>
    /// Value Name
    public static void IniWriteValue(string sPath,string Section, string Key, string Value)
    {
        WritePrivateProfileString(Section, Key, Value, sPath);
    }

    /// <summary>
    /// Read Data Value From the Ini File
    /// </summary>
    /// <PARAM name="Section"></PARAM>
    /// <PARAM name="Key"></PARAM>
    /// <PARAM name="Path"></PARAM>
    /// <returns></returns>
    public static string IniReadValue(string sPath,string Section, string Key)
    {
        StringBuilder temp = new StringBuilder(255);
        int i = GetPrivateProfileString(Section, Key, "", temp,
                                        255, sPath);
        return temp.ToString();

    }

}

The use is obviouse since its a static class, just call IniFileManager.IniWriteValue for readsing a section or IniFileManager.IniReadValue for reading a section.

Answer 17

You should read and write data from xml files since you can save a whole object to xml and also you can populate a object from a saved xml. It is better an easy to manipulate objects.

Here is how to do it: Write Object Data to an XML File: https://msdn.microsoft.com/en-us/library/ms172873.aspx Read Object Data from an XML File: https://msdn.microsoft.com/en-us/library/ms172872.aspx