C＃识别for循环中的项目

Question

I've created a for loop that will be used to display 8 items per section, but I'm trying to identify certain items within the loop. For instance I want to identify the first two items, then fifth and sixth but can seem to get my identification techniques correct.

for (int i = 0; i < Model.Count; i++){
    var item = Model[i]
    if ((i + 1) % 3 != 0 && (i + 1) % 4 != 0){
        // What i want to display here
    }
    else{
        // Something else I want to display
    }
}

This kind of works for the first four items but for the last four items it doesn't seem to work

Answer 1

for (int i = 0; i < Model.Count; i++){
    var item = Model[i]
    int aux = i%4;
    if (aux==0|| aux==1){
        // What i want to display here
    }
    else{
        // Something else I want to display
    }
}

Answer 2

Instead of messing around with modulo a 'cheap' trick is to just have a counter that keeps track of where you are and resets on each loop.

// Dummy list to represent whatever 'Model' is
var model = new List<string> { "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten", "eleven", "twelve" };

// A counter that keeps track of whether we're on 1, 2, 5 or 6
var counter = 1;

// Your loop
for (int i = 0; i < model.Count; i++)
{
    // Get the item as you've shown
    var item = model[i];

    // Check whether we want this item or not
    if (counter == 1 || counter == 2 || counter == 5 || counter == 6)
    {
        // Display
        Console.WriteLine("Displayed: " + item);
    }
    else
    {
        // Do whatever else
        Console.WriteLine("Skipped: " + item);
    }

    // Increase the counter
    counter++;

    // Reset the counter if we're into the next batch of 8
    if (counter > 8)
        counter = 1;
}   

Output:

Displayed: one
Displayed: two
Skipped: three
Skipped: four
Displayed: five
Displayed: six
Skipped: seven
Skipped: eight
Displayed: nine
Displayed: ten
Skipped: eleven
Skipped: twelve

I admit it's not very 'fancy' but it works fine and is easy to understand.