traversing two lists simultaneously

[Pita32]

suppose you have two lists of the same size, i.e. same number of elements List a, List b is it possible to traverse the two lists simultaneously and compare the values? Element 1 in list a to element 1 in list b, element 2 in list a to element 2 in list b, etc. I use a Foreach when traversing lists, but am unsure of how to do a side by side comparison of list b when I am traversing list a. Thanks

[OriginalGriff]

Use a for instead of a foreach:

for (int i = 0; i < a.Length && i < b.Length; i++)
{
if (a[i] == b[i])
{
...
}
}

"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony AntiTwitter: @DalekDave is now a follower!

[Dave Kreskowiak]

Lists work just like arrays, so you can use either an enumerator (foreach) or you can use an index value:

for(int index = 0; index < someValue; ++index)
{

    if (a\[index\] == b\[index\])
    {
        // true
    }
    else
    {
        // false
    }
}

Asking questions is a skill CodeProject Forum Guidelines Google: C# How to debug code Seriously, go read these articles.
Dave Kreskowiak

[Lost User]

If the "lengths" of a and b are equal, you can maintain your own index:

int i = 0;

foreach ( int value in a ){
bool result = (value == b[i++]);
}

Note the suffix (++) operator in this case.

It was only in wine that he laid down no limit for himself, but he did not allow himself to be confused by it. ― Confucian Analects: Rules of Confucius about his food

[James Curran]

You could also use the `Zip` extension method, which takes a lambda with two arguments, which is called with the corresponding elements. It yields a IEnumerable of the results of those lambda calls.

var a = {1,2,3,4};
var b = {2,3,4,5}
var c = a.Zip(b, (aa, bb)=> aa \* bb).ToList();
//  c = {2,  6, 12, 20};

//  :

var d = {…};
var e = {…};

if (d.Zip(e, (dd, ee)=> dd==ee).All()) 
{   // tests if all elements are equals  (same as a.SequenceEqual(b))

Truth, James