How to get substring from string containing newlines

Question

If the response length is more than provided, I'm trying to obtain a substring from it and loop through it. My code is as follows:

string response = //response from API
if (response.Length > 4096)
{
    for (int i = 0; i < response.Length; i += 4096)
    {
        string rplymsg = response.Substring(i, 4095);
        //other code using rplymsg 
    }
}
else
{
    //other code using response 
}

I experimented with String. In debugging, the Substring method returns a substring of the provided length, but the real substring length is longer. (I double-checked this by pasting a substring into notepad++.)

I believe the issue is caused by the response string's substring rplymsg, which contains new lines n. Is there a better way to count the number of newlines in a string so that I may extract substrings based on that length?

Answer 1

If you want to maintain the newline characters if a string is less than 4096 characters, I believe you should divide the string on that character rather than just String. Substring(...) consider using String. Split(...) also processes the array of strings it returns. e.g.:

    string response = "abcd\nefgh\nijklmnop\nrst\n";
    var maxLength = 5;
    var delimiter = new char[]{'\n'};
    var strings = response.Split(delimiter, StringSplitOptions.None); 
      

    foreach(var s in strings)
    {
        var delimited = s + '\n';//add newline as Split removes them from the result
        if(delimited.Length>maxLength)
        {
            var sub = delimited;
            while(sub.Length>maxLength)
            {
               var p = sub.Substring(0, maxLength-1);
               Console.WriteLine($"partial :{p}");
               sub = sub.Remove(0,maxLength-1);
            }
            Console.WriteLine($"end :{sub}");
        }
        else
        {
            Console.WriteLine($"original :{delimited}");
        }
    }

The code will need some idea to you. This is by no means perfect.