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CSharp · Console

/Program.cs

using System;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;

namespace Console1;

public static class Program
{
    public static void Main()
    {
        string text = "DELICIOUS FOOD";

        int cols  = 5;
        int rows  = (text.Length + cols - 1) / cols;
        var array = new char[rows, cols];
        var span  = AsSpan<char>(array); // Create a span that encompasses all the elements of 'array' as a single span.

        text.CopyTo(span);                 // Copy the text to the span; this will wrap at the correct places.
        span.Slice(text.Length).Fill('X'); // Fill the remainder of the span with 'X'.

        // Print the result.

        for (int r = 0; r < rows; ++r)
        {
            for (int c = 0; c < cols; ++c)
            {
                Console.Write(array[r, c]);
            }

            Console.WriteLine();
        }
    }

    public static Span<T> AsSpan<T>(Array array)
    {
        return MemoryMarshal.CreateSpan(
            ref Unsafe.As<byte, T>(ref MemoryMarshal.GetArrayDataReference(array)),
            array.Length);
    }
}