CODEWITHSUNDEEP
c#stringobjectdynamic
user469453
user469453

Reputation: 349

Creating objects dynamically in loop

I have an array of strings that I am looping through. I would like to loop through the array and on each iteration, create a new object with a name that matches the string value.

For example;

string[] array = new string[] { "one", "two", "three" };

class myClass(){

    public myClass(){
    }
}

foreach (string name in array)
{
   myClass *value of name here* = new myClass(); 
}

Would result in three objects being instantiated, with the names "one", "two" and "three".

Is this possible or is there are better solution?

Upvotes: 12

Views: 30415

Answers (9)

Michael Buen
Michael Buen

Reputation: 39483

Not applicable to C#, or any statically-typed language for that matter.

For curiosity, I tried if what I remembered in PHP(creating variables on-the-fly) is still correct.

It's still the same PHP, last I used it was year 2000. You can generate variables on-the-fly, not saying it's advisable though, it pollutes the global variables, it can corrupt some existing variable or object with same name.

https://ideone.com/nJDiou

<?php

class MyClass
{
    private $v;
    function __construct($x) {
        $this->v = $x;
    }
    public function getValue() {
        return $this->v;
    }
}

$one = new MyClass("I'm tough!");

echo "The one: " . $one->getValue() . "\n";

$i = 0;
foreach(array("one","two","three") as $h) {
   $$h = new MyClass("Says who? " . ++$i);
}

echo "The one: " . $one->getValue() . "\n";

echo $two->getValue() . "\n";
echo $three->getValue() . "\n";

echo "loop\n";

foreach(array("three","one","two") as $h) {
   echo $$h->getValue() . "\n";
}

?>

Outputs:

The one: I'm tough!
The one: Says who? 1
Says who? 2
Says who? 3
loop
Says who? 3
Says who? 1
Says who? 2

Upvotes: 0

Michael Buen
Michael Buen

Reputation: 39483

What are you trying to do is not possible in statically-typed language. IIRC, that's possible on PHP, and it's not advisable though.

Use dictionary instead: http://ideone.com/vChWD

using System;
using System.Collections.Generic;

class myClass{

    public string Name { get; set; }
    public myClass(){
    }
}

class MainClass
{

    public static void Main() 
    {
        string[] array = new string[] { "one", "two", "three" };
        IDictionary<string,myClass> col= new Dictionary<string,myClass>();
        foreach (string name in array)
        {
              col[name] = new myClass { Name = "hahah " + name  + "!"};
        }

        foreach(var x in col.Values)
        {
              Console.WriteLine(x.Name);
        }

        Console.WriteLine("Test");
        Console.WriteLine(col["two"].Name);
    }
}

Output:

hahah one!
hahah two!
hahah three!
Test
hahah two!

Upvotes: 12

aabiro
aabiro

Reputation: 4288

You can use this approach:

  var array = [srt1, srt2, str3];
  var other_array = [];

  for(var i = 0; i <  array.length; i++){
    other_array.push({
    name: array[i]
    })
  }

And for lookup it is easy to find the instance you need by filtering:

var instance1 = other_array.filter(function(result) {
return result.name == 'str1';
});

Upvotes: 1

Nikhil Agrawal
Nikhil Agrawal

Reputation: 48600

While others have given you an alternate but no one is telling why do they recommend you that.

That's because You cannot access object with dynamic names.

(Food for thought: Just think for a moment if you could do so, how will you access them before they are even coded/named.)

Instead create a Dictionary<string, myClass> as others mentioned.

Upvotes: 5

Willem T
Willem T

Reputation: 104

You can use lists to store the objects so you can access them

list<myClass> myClasses = new List<myClass>();
foreach (myClass object in myClasses)
{
    //preform interaction with your classes here 
}

Upvotes: 0

Asif Mushtaq
Asif Mushtaq

Reputation: 13150

You can use the following code.

string[] array = new string[] { "one", "two", "three" };
Dictionary<String, myClass> list;
class myClass(){

   public myClass(){
   list = new Dictionary<String, myClass>();
   }
 } 

 foreach (string name in array)
 {
    list.Add(name, new myClass())
 }

Upvotes: 0

pstrjds
pstrjds

Reputation: 17448

You could do something like this -

Dictionary<string, myClass> classes = new Dictionary<string, myClass>();

foreach(string name in array)
{
    classes[name] = new myClass();
}

Then you can refer to the named instances later 

classes[name].MyClassMethod();

Upvotes: 0

Oded
Oded

Reputation: 499392

Looks like you need a list of dictionary of your objects:

var myClassDictionary = new Dictionary<string,myClass>();

foreach (string name in array)
{
  myClassDicationry.Add(name, new myClass());
}

// usage:
// myClass["one"] <- an instance of myClass

There are no programming languages that I know of that let you define variable names in runtime.

Upvotes: 0

Tim Schmelter
Tim Schmelter

Reputation: 460360

Use a Dictionary<String, myClass> instead:

var dict= new Dictionary<String, myClass>();

foreach (string name in array)
{
    dict.Add(name, new myClass());
}

Now you can access the myClass instances by your names:

var one = dict["one"];

or in a loop:

foreach (string name in array)
{
    myClass m = dict[ name ];
}

Upvotes: 4

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