pig latin Code gets skipped? C#

Question

I programmed a code for the pig latin puzzle but the while loop gets skipped(?) and it just outputs the original sentence...

Here's the code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace SoloLearn
{
class Program
{
static void Main(string[] args)
{
string sentence = Console.ReadLine();
int i = 0;
char letter;

sentence += " ";

while(i <= sentence.Length)
{
letter = sentence[i];
sentence.Remove(i, 1);

while(sentence[i] != ' ')
{
i++;
}

sentence.Insert(i, letter + "ay");
i += 4;
}

Console.Write(sentence);
}
}
}

Answer 1

The while loop gets not skipped.
while(i < sentence.Length)
The last index of a string is length - 1. So i should not get = length.

.Remove() & .Insert() return a String:

sentence = sentence.Remove()
same for Insert()

Answer 2

Tanks a lot!

Answer 3

Drahnoel Your welcome :)