print three lists using foreach

Question

I have 3 lists like List A=new List (); List B=new List (); List C=new List (); How can I print the contents of the lists like this: first item of list A first item of list B first item of list C second item of list A second item of list B second item of list C third item of list A third item of list B third item of list C ....

Matthew Cochran · Answer

Here's a different way to look at it with the 3.5 framework -Matt class Program { static void Main ( string [] args) { List string > A = new List string >(){ 1  2  3 }; List string > B = new List string >(){ W  X  Y  Z }; List string > C = new List string >(){ !  @ }; new List String >[] { A B C } .Collate() .ForEach( val => Console .WriteLine( val )); Console .ReadLine(); } } public static class Extensions { public static IEnumerable Collate ( this IEnumerable IEnumerable > items) { Int32 i length =items.Count(); IEnumerator [] en = items.Convert(x => x.GetEnumerator()).ToArray(); Boolean [] finished = new Boolean [length]; // set to 'false' by default while ( finished.Contains( false ) ) { for (i = 0; i { // we are finished if there are no more items in the enumerator finished[i] = ! en[i].MoveNext(); if (!finished[i]) yield return en[i].Current; } } } public static IEnumerable Convert ( this IEnumerable input Func f) { foreach (T item in input) yield return f(item); } public static void ForEach ( this IEnumerable items Action act) { foreach (T item in items) act(item); } }

Alan · Answer

OK this is how I'd suggest doing that: using System; using System.Collections.Generic; class Program { static void Main() { List A= new List (); A.Add(A1); A.Add(A2); List B= new List (); B.Add(B1); B.Add(B2); B.Add(B3); List C= new List (); C.Add(C1); C.Add(C2); C.Add(C3); C.Add(C4); // determine the largest element count int largest = Math.Max(A.Count B.Count); largest = Math.Max(largest C.Count); for (int i = 0; i { if (i Console.WriteLine(A[i]); if (i Console.WriteLine(B[i]); if (i Console.WriteLine(C[i]); } Console.ReadKey(); } } To use foreach() you'd have to 'interleave' the three Lists into a single List so I think the for() statement is the best approach here.

kiki · Answer

yes this is the idea exactly

Alan · Answer

I might be able to propose something but I need to know how you'd want to deal with the 'excess' elements. Suppose that A had 2 elements B had 3 elements and C had 4 elements. How would you want to print that out? Something like this may be: A1 B1 C1 A2 B2 C2 B3 C3 C4

kiki · Answer

I understand this.... but the problem is that in my program the lists do not have the same size. Do you have something to propose for that? I thought foreach statement was the solution to my problem because I dont need to know the sizes of the lists and because it's quicker in execution.

Alan · Answer

Assuming that all 3 lists have the same number of elements you could do something like this: using System; using System.Collections.Generic; class Program { static void Main() { List A= new List (); A.Add(A1); A.Add(A2); A.Add(A3); List B= new List (); B.Add(B1); B.Add(B2); B.Add(B3); List C= new List (); C.Add(C1); C.Add(C2); C.Add(C3); for (int i = 0; i { Console.WriteLine(A[i]); Console.WriteLine(B[i]); Console.WriteLine(C[i]); } Console.ReadKey(); } } I can't see how you could use foreach() here as you need to know the index of the element to be printed.

print three lists <> using foreach