C# if condition isn't true do something

Question

my code:

string[] code = new string[9];
int[] intCode = new int[9];

int cd = 0, dvd = 0, video = 0, book = 0;
for (int i = 0; i < 10; i++)
{

    Console.Write("Enter code#{0}: ",i+1);
    code[i] = Console.ReadLine();
    if (code[i].Length==5)
    {
        intCode[i] = Convert.ToInt32(code[i]);
        intCode[i] /= 100000;
        if (intCode[i] == 1)
        {
            cd++;
            break;

        }
        if (intCode[i] == 2)
        {
            dvd++;
            break;
        }
        if (intCode[i] == 3)
        {
            video++;
            break;
        }
        if (intCode[i] == 4)
        {
            book++;
            break;
        }
    }
    else
    {
        Console.WriteLine("INVALID CODE");

    }

}

Basically what i want to do is else{do some thing here} to ask the user to reinput the number, instead of going to for loop and icrementing i and asking the user for new input.

Answer 1

Use a combination of while and switch:

        string[] code = new string[9];
        int[] intCode = new int[9];
        int cd = 0, dvd = 0, video = 0, book = 0;
        for (int i = 0; i < 10; i++)
        {
            bool isCorrectInput = false;
            while (!isCorrectInput)
            {
                isCorrectInput = true;
                Console.Write("Enter code#{0}: ", i+1);
                code[i] = Console.ReadLine();
                if (code[i].Length == 1)
                {
                    intCode[i] = Convert.ToInt32(code[i]);
                    // intCode  /= 100000;
                    switch (intCode[i])
                    {
                        case 1:
                            cd++;
                            break;
                        case 2:
                            dvd++;
                            break;
                        case 3:
                            video++;
                            break;
                        case 4:
                            book++;
                            break;
                        default:
                            isCorrectInput = false;
                            break;
                    }
                }
                else
                    isCorrectInput = false;
                if (!isCorrectInput)
                    Console.WriteLine("INVALID CODE ENTERED!");
            }
        }

EDIT: Should be what you want now, also corrected your bugs

Answer 2

In the else block:

else
{
    Console.WriteLine("INVALID CODE");
    i -= 1;
}