如何使方法接收两种不同的数据类型并只返回其中一种C＃？

Question

I've started learning C# by myself this week, and I might have trouble understanding a few concepts so sorry for any difficulty understanding me. I want to create a method which receives int[] and int, but returns only int[]. I received two errors.

For the main method:

Cannot implicitly convert type 'int[]' to 'int'

    static void Main(string[] args)
    {
        int[] Num = new int[5];
        int i;
        for (i = 0; i < 5; i++)
            Num[i] = NumGen(Num, i);
    }

The created method:

Cannot implicitly convert type 'int' to 'int[]'

  static int[] NumGen(int[] Num, int i)
    {
        Random rndm = new Random();
        Num[i] = rndm.Next(100) + 1;
        return Num[i];

     }

I want to understand what I've done wrong and how to avoid this mistake in the future. Thank you for the answers in advance!

EDIT: Thanks everyone, your suggestions solved the problem. :)

Answer 1

Just the return type of NumGen - should be int :

static int NumGen(int[] Num, int i)
{
    Random rndm = new Random();
    Num[i] = rndm.Next(100) + 1;
    return Num[i];
}

BUT: your code has a serious bug. new Random() like that will produce the same value every time, due to how it is seeded via the clock. A better approach would be:

static int NumGen(Random rndm, int[] Num, int i)
{
    Num[i] = rndm.Next(100) + 1;
    return Num[i];
}
static void Main(string[] args)
{
    int[] Num = new int[5];
    Random rand = new Random();
    for (int i = 0; i < 5; i++)
        Num[i] = NumGen(rand, Num, i);
}

Or more cleanly:

static int Randomize(Random rndm)
{
    return rndm.Next(100) + 1;
}
static void Main(string[] args)
{
    int[] Num = new int[5];
    Random rand = new Random();
    for (int i = 0; i < 5; i++) Num[i] = Randomize(rand);
}

Answer 2

You're declaring a method that returns an array of int ( int[] NumGen() ), while assigning its return value to an int ( Num[i] = NumGen() ) and only returning a single int from it ( return Num[i]; ).

If you can explain what this code is expected to do, perhaps we can suggest what this code should look like.

You can probably replace it all with:

var random = new Random();
int[] randomNumbers = Enumerable.Range(0, 5)
                                .Select(i => random.Next(100) + 1)
                                .ToArray();

But that would miss the point of learning about arrays and their syntax .

Answer 3

Num[i] is an int, not int[]. Because it is an item from the int array and any element in that array is int. So replace first line:

static int NumGen(int[] Num, int i)
    {
        Random rndm = new Random();
        Num[i] = rndm.Next(100) + 1;
        return Num[i];

     }

Answer 4

you want your function to return int (a number) not int[] (an array of numbers)

change to

static int NumGen(int[] Num, int i)

and it should be ok ;)