how this can be done

that is good work, but not what i aim to. i need to make the program to take a number between 2,9 and the program make possible combinations in form of sets where {1,2} the same as {2,1} i don't need the program to display both sets. also when you give the program a number between 2,9 for example : for 2 {1,2} for 3 {1,2,3} for 4 {1,2,3,4} and continue displaying all possible combination in a form of sets which contains a number of elements specified by the user of the program. if you don't understand me please post a reply.

Not sure if it's entirely correct. but here's my try :) using System; namespace csConsole { class NumberSets { static void Main(string[] args) { int[] intset = new int[]{1,2,3,4,5,6,7,8,9,10}; int count = 0; for (int i = 0; i < intset.Length; i++) { for (int j = 0; j < intset.Length; j++) { Console.WriteLine(string.Format("({0}, {1})" ,intset[i] ,intset[j])); count++; if(intset[i] != intset[j]) { Console.WriteLine(string.Format("({1}, {0})" ,intset[i] ,intset[j])); count++; } } } Console.WriteLine("\n\n" + count + " results"); Console.Read(); } } }

forget the previouse now , and try to make a solution for the following problem: for you have a set A={1,2,3,4,5,6,7,8,9,10} and i need to make all possible combination between 1,2,3,4,..,or 9 elements for example: i need the output in case of combination of two elements to be as follows:- {1,2}{ 1,3} {1,4} {1,5} .... {1,10} {2,3} {2,4} ...... {2,10} ... etc..

What is "[i]" in "MyArray[i]"? Let me see if i understood. You generate a equation string like "2x+3y", but the equation is stored in an array like Y = {"2", "x", "+", "3", "y"} And you want to assign values to y an x to get a result. Is this right?

i am sorry , no one can understand me. i will show you my question in another example, an d i hope you will understand it. look:>> y = "myArray[i]" // where y is string after i make this equation that was generated by any way... i need to use "myArray[i]" in a for loop for example: for(i=0;i<10;i++) { Console.writeline(myArray[i]); /*here " myArray[i] was gotten from the above equation - y="myArray[i]" which was generated by someway and i don't know what is the result from that way.*/ } please if you don't understand it again tell me what you don't understand and i will show it for you.

If you want to use the equation in another method I suppose you could make a class. In that class you write a public static method that implements the equation. Then you could access that equation from anywhere. MyClass.Equation(); This is the only part of your question that I can understand :) Sorry

i am waiting your answer

you get the first part of my question well. but, i mean that: 1- i don't need sum to be int, i need it as string - any datatype - that helps me to produce some of myarray elements in the form " 1,2,3" - separated by commas. 2- second, look at the follwing example if i get f(x) = 2x+3 suppose that 2x+3 is generated by for loop and f(x) the object which contains this equation how can i use this equation not the object in another piece of code i.e in another method. NOW i think you got my question correctly.