Question

I need a tips for adding a line return after 15 ‘,’

like that

db 4Dh, 5Ah, 80h, 00h, 01h, 00h, 00h, 00h, 04h, 00h, 10h, 00h, 0FFh, 0FFh, 00h, <-- return line here

Answer 1

An alternative to the StringBuilder approach:

static class StringExt
{
    public static string InsertAfterEvery(
        this string source, string insert, int every, string find)
    {
        int numberFound = 0;
        int index = 0;
        while (index < source.Length && index > -1)
        {
            index = source.IndexOf(find, index) + find.Length;
            numberFound++;
            if (numberFound % every == 0)
            {
                source = source.Insert(index, insert);
                index += insert.Length;
            }
        }
        return source;
    }
}

// I used 3 rather than 15
Console.WriteLine(
    "db 4Dh, 5Ah, 80h, 00h, 01h, 00h, 00h, 00h, 04h,".InsertAfterEvery(
        Environment.NewLine, 3, ","));