Develop Reference

Is it possible to easily get variable names in a method as well as their values

Following my Is it possible to have a Function that takes any number of variables of any type?
I have the function that gets any number of any type of variables and it works perfectly
public string funcVars(params object[] paths)
{
string strVars = String.Join(", ", paths.Select(x => x.ToString()));
return strVars;
}
To call it I'd simply need to
string someString ="asd"; int someInt = 123; bool someBool=false;
funcVars(someString,someInt,someBool);
And the output would be
asd,123,false
is there any simple way I can also get the variable names as well as their values, so the output would be
asd,123,false,someString,someInt,someBool //(or any other similar form)
Or do I need to hardcode the names every time I call my method ?
funcVars("someString","someInt","someBool",someString,someInt,someBool);

What you really should be doing is creating a class to hold your variables:
internal class MyValues
{
internal string SomeString { get; set; }
internal int SomeInt { get; set; }
internal bool SomeBool { get; set; }
}
Then you can pass an instance of your class:
var mv = new MyValues() { SomeString = "asd", SomeInt = 123, SomeBool = false };
funcVars(mv);
Here is funcVars:
public string funcVars(MyValues values)
{
string strVars =
String.Join(", ", new[] { values.SomeString,
values.SomeInt.ToString(), values.SomeBool.ToString() });
return strVars;
}

Straight up stealing roy.ap's code and adding the "nameof()" method since getting the name of the property seemed to be apart of the question.
class Program
{
internal class MyValues
{
internal string SomeString { get; set; }
internal int SomeInt { get; set; }
internal bool SomeBool { get; set; }
}
static void Main(string[] args)
{
var mv = new MyValues() { SomeString = "asd", SomeInt = 123, SomeBool = false };
Console.WriteLine(funcVars(mv));
Console.ReadLine();
}
public static string funcVars(MyValues values)
{
string strVars =
String.Join(", ", new[]
{
nameof(values.SomeString), values.SomeString,
nameof(values.SomeInt), values.SomeInt.ToString(),
nameof(values.SomeBool), values.SomeBool.ToString()
});
return strVars;
}
}
There really isn't a way to get the variable names via the the function itself because the scope changes once you're in the method. That is even if you pass an array of objects, if you perform a foreach to go through each object you will give the individual objects a new scope specific name.

No, because the variables are not actually passed
No it is not possible, because the variables themselves are not actually passed. Their values are passed.
Consider this code:
string someString ="asd"; int someInt = 123; bool someBool=false;
funcVars(someString,someInt,someBool);
In your call to funcVars, all the parameters are passed by value. All three variables are copied, and copy of them is put on the stack. These stack variables are identified by completely different symbols-- (e.g. paths[0],paths[1], etc.)
After all, what would happen if you called it like this?
funcVars("Hello",245+25,test != null);
Obviously those values do not have variable names. There is no way your function can possibly retrieve what doesn't exist.
Use ExpandoObject instead
The System.Dynamic.ExpandoObject seems like a really good fit for this problem.
var args = new System.Dynamic.ExpandoObject();
args.SomeString = "hello";
args.SomeInt = 32;
args.SomeBool = false;
funcVars(args);
public static string funcVars(ExpandoObject inputs)
{
var sb = new StringBuilder();
foreach (KeyValuePair<string, object> kvp in inputs)
{
sb.Append(String.Format("{0} = {1}", kvp.Key, kvp.Value);
}
return sb.ToString();
}

How to 'select' object field when you only have a string with exact name as the object field

Sorry if the title is not clear, it was hard to properly word this question.
I have an object named Stuff and MoreStuff.
public class Stuff()
{
public string Field1;
public string Field2;
}
public class MoreStuff()
{
public string Field3;
public string Field4;
}
I want to create something that adds a value to Field1 when the string fieldValue = 'Field1'
To make it more clear, something like this. But I want to have it generic for any object.:
string fieldValue = 'Field1'
Stuff thing = new Stuff();
checkField(fieldValue);
thing.fieldValue = 'checked';
string fieldValue = 'Field4'
MoreStuff moreThing = new MoreStuff();
checkField(fieldValue);
moreThing.fieldValue = 'checked';
Is this possible to do in C#? I can't find anything about it, also hard to search for a question like this.

You can use reflection:
string fieldName = "Field1";
Stuff thing = new Stuff();
thing.GetType().GetField(fieldName).SetValue(thing, "checked");

Square test = new Square();
test.Field1 = "sdflsjf";
test.Field2 = "sdlfksj";
test.Field3 = "sldfjs";
foreach (PropertyInfo propertyInfo in test.GetType().GetProperties())
{
if (propertyInfo.Name == "Field2")
propertyInfo.SetValue(test, "checked");
}
This uses System.Reflection to do approximately what you're looking for by the sounds of it.

Handling data with lists

Is this bad practice? Or is it completely fine to do this
private readonly List<KeyValuePair<GameType, KeyValuePair<string, string>>> _tempStats = new List<KeyValuePair<GameType, KeyValuePair<string, string>>>();
GameType is an enumerator by the way.
I have data that I am downloading from a table that has a few different GameTypes with two strings associated with them. So it will parse the data and determines what GameType to assign it, and it finds the tables Key and it's Value. And it works, it stores the information and I am able to retrieve it with no problems, but it just seems like having a list of a KeyValuePair with a KeyValuePair isn't right, but maybe it is. Would using a tuple be a better approach?
My current usage of the list
private void ParseNodeText(string nText, GameType gmode)
{
_tempStats.Clear();
var reader = new StringReader(nText);
while((nText = reader.ReadLine()) != null)
{
nText = nText.Replace(" ", "");
if (nText == "")
{
continue;
}
string statType = Regex.Replace(nText, "[^A-Za-z]", "");
string statValue = Regex.Replace(nText, "[^0-9]", "");
// Console.WriteLine(gmode + " : Found line with Type of {0} and a value of {1}",statType,statValue);
_tempStats.Add(new KeyValuePair<GameType, KeyValuePair<string, string>>(gmode, new KeyValuePair<string, string>(statType, statValue)));
}
}

Your Solution is fine, but not that good readable.
You could do something like this:
private readonly List<GameStats> _tempStats = new List<GameStats>();
and GameStats is a own written simple Class:
public class GameStats
{
public GameType Type { get; set; }
public string StatType { get; set; }
public string StatValue { get; set; }
public GameStats(GameType gameType, string statType, string statValue)
{
this.Type = gameType;
this.StatType = statType;
this.StatValue = statValue;
}
}
and add it to your list like:
_tempStats.Add(new GameStats(gmode, statType, statValue));
i think, this looks good and will do it.

Read values from a non-delimited string into class object

I have a string with the following structure:
Student Name________AgeAddress_______________________Bithday___Lvl
Example:
Jonh Smith 016Some place in NY, USA 01/01/2014L01
As you can see, there is no delimited character like | or ,
Also, there is no space between fields (if you check, there is no space between Age/Address and Birthday/Level.
The size of each field is static so if data's length is less then it will contains white spaces.
I have a class that need to be filled with that information:
public class StudentData
{
public char[] _name = new char[20];
public string name;
public char[] _age = new char[3];
public string age;
public char[] _address = new char[30];
public string address;
public char[] _bday = new char[10];
public string bday;
public char[] _level = new char[3];
public string level;
}
Is there any way to do this automatically and dynamically?
I mean I really don't want to code like this:
myClass.name = stringLine.substring(0,19);
myClass.age = stringLine.substring(20,22);
That's because I have way more fields that the ones added in this example & way more string lines with other different data.
Update: There were supposed to be a lot of spaces between "Smith" and "016", but I don't know how to edit it.
Update2: If I use StringReader.Read() I can evade to use substring and indexes, but it isn't still so dynamically because I would need to repeat those 3 lines for each field.
StringReader reader = new StringReader(stringLine);
reader.Read(myClass._name, 0 myClass._name.Length);
myClass.name = new string(myClass._name);

Given your requirement I came up with an interesting solution. All be-it it may be more complex and longer than using the String.SubString() method as stated.
However this solution is transferable to other types and other string. I used a concept of Attributes, Properties, and Reflection to parse a string by a Fixed Length and setting the class Properties.
Note I did change your StudentData class to follow a more conventional coding style. Following this handy guide on MSDN: http://msdn.microsoft.com/en-us/library/xzf533w0(v=vs.71).aspx
Here is the new StudentData class. Note it uses the properties as opposed to fields. (Not discussed here).
public class StudentData
{
string name;
string age;
string address;
string bday;
string level;
[FixedLengthDelimeter(0, 20)]
public string Name { get { return this.name; } set { this.name = value; } }
[FixedLengthDelimeter(1, 3)]
public string Age { get { return this.age; } set { this.age = value; } }
[FixedLengthDelimeter(2, 30)]
public string Address { get { return this.address; } set { this.address = value; } }
[FixedLengthDelimeter(3, 10)]
public string BDay { get { return this.bday; } set { this.bday = value; } }
[FixedLengthDelimeter(4, 3)]
public string Level { get { return this.level; } set { this.level = value; } }
}
Note on each of the properties there is an Attribute called FixedLengthDelimeter that takes two parameters.
OrderNumber
FixedLength
The OrderNumber parameter denotes the order in the string (not the position) but the order in which we process from the string. The second parameter denotes the Length of the string when parsing the string. Here is the full attribute class.
[AttributeUsage(AttributeTargets.Property, AllowMultiple = false)]
public sealed class FixedLengthDelimeterAttribute : Attribute
{
public FixedLengthDelimeterAttribute(int orderNumber, int fixedLength)
{
this.fixedLength = fixedLength;
this.orderNumber = orderNumber;
}
readonly int fixedLength;
readonly int orderNumber;
public int FixedLength { get { return this.fixedLength; } }
public int OrderNumber { get { return this.orderNumber; } }
}
Now the attribute is simple enough. Accepts the two paramters we discussed eariler in the constructor.
Finally there is another method to parse the string into the object type such as.
public static class FixedLengthFormatter
{
public static T ParseString<T>(string inputString)
{
Type tType = typeof(T);
var properties = tType.GetProperties(BindingFlags.Instance | BindingFlags.Public); //;.Where(x => x.GetCustomAttributes(typeof(FixedLengthDelimeterAttribute), false).Count() > 0);
T newT = (T)Activator.CreateInstance(tType);
Dictionary<PropertyInfo, FixedLengthDelimeterAttribute> dictionary = new Dictionary<PropertyInfo, FixedLengthDelimeterAttribute>();
foreach (var property in properties)
{
var atts = property.GetCustomAttributes(typeof(FixedLengthDelimeterAttribute), false);
if (atts.Length == 0)
continue;
dictionary[property] = atts[0] as FixedLengthDelimeterAttribute;
}
foreach (var kvp in dictionary.OrderBy(x => x.Value.OrderNumber))
{
int length = kvp.Value.FixedLength;
if (inputString.Length < length)
throw new Exception("error on attribute order number:" + kvp.Value.OrderNumber + " the string is too short.");
string piece = inputString.Substring(0, length);
inputString = inputString.Substring(length);
kvp.Key.SetValue(newT, piece.Trim(), null);
}
return newT;
}
}
The method above is what does the string parsing. It is a pretty basic utility that reads all the properties that have the FixedLengthDelimeter attribute applied a Dictionary. That dictionary is then enumerated (ordered by OrderNumber) and then calling the SubString() method twice on the input string.
The first substring is to parse the next Token while the second substring resets the inputString to start processing the next token.
Finally as it is parsing the string it is then applying the parsed string to the property of the class Type provided to the method.
Now this can be used simply like this:
string data1 = "Jonh Smith 016Some place in NY, USA 01/01/2014L01";
StudentData student = FixedLengthFormatter.ParseString<StudentData>(data1);
What this does:
Parses a string against property attributes in a fixed length format.
What this does not do:
It does convert the parsed strings to another type. Therefore all the properties must be a string. (this can be easily adapted by adding some type casting logic in).
It is not well tested. This is only tested against a few samples.
It is not by all means the only or best solution out there.

You could use FileHelpers library (NuGet).
Just define the structure of your input file with attributes:
[FixedLengthRecord]
public class StudentData
{
[FieldFixedLength(20)]
[FieldTrim(TrimMode.Right)]
public string name;
[FieldFixedLength(3)]
public string age;
[FieldFixedLength(30)]
[FieldTrim(TrimMode.Right)]
public string address;
[FieldFixedLength(10)]
public string bday;
[FieldFixedLength(3)]
public string level;
}
Then simply read the file using FileHelperEngine<T>:
var engine = new FileHelperEngine<StudentData>();
var students = engine.ReadFile(filename);

Using DefaultIfEmpty with an object?

I saw an example on MSDN where it would let you specify the default value if nothing is returned. See below:
List<int> months = new List<int> { };
int firstMonth2 = months.DefaultIfEmpty(1).First();
Is it possible to use this functionality with an object? Example:
class object
{
int id;
string name;
}
code:
List<myObjec> objs = new List<myObjec> {};
string defaultName = objs.DefaultIfEmpty(/*something to define object in here*/).name;
UPDATE:
I was thinking I could do something like this:
List<myObjec> objs = new List<myObjec> {};
string defaultName = objs.DefaultIfEmpty(new myObjec(-1,"test")).name;
But haven't been able to. It should be noted that I am actually trying to use this method on an object defined in my DBML using LINQ-To-SQL. Not sure if that makes a difference in this case or not.

You need to pass an instantiated class as a parameter of the DefaultIfEmpty.
class Program
{
static void Main(string[] args)
{
var lTest = new List<Test>();
var s = lTest.DefaultIfEmpty(new Test() { i = 1, name = "testing" }).First().name;
Console.WriteLine(s);
Console.ReadLine();
}
}
public class Test
{
public int i { get; set; }
public string name { get; set; }
}
To add to it and make it a bit more elegant (IMO) add a default constructor:
class Program
{
static void Main(string[] args)
{
var lTest = new List<Test>();
var s = lTest.DefaultIfEmpty(new Test()).First().name;
Console.WriteLine(s);
Console.ReadLine();
}
}
public class Test
{
public int i { get; set; }
public string name { get; set; }
public Test() { i = 2; name = "testing2"; }
}

As per the MSDN page on this Extension Method you can do what you want:
http://msdn.microsoft.com/en-us/library/bb355419.aspx
Check the sample on this page for an example on how to use this with an object.

i must admit i am not too sure i understand your question, but i'll try to suggest using double question mark if the returned object might be null. Like so:
myList.FirstOrDefault() ?? new myObject();

You can create a default Object Like this:
Object o_Obj_Default = new Object();
o_Obj_Default.id = 3;
o_Obj_Default.name = "C";
And add it to your default value :
string defaultName = objs.DefaultIfEmpty(o_Obj_Default).First().name;
If your list "objs" is empty, the result will be "C"