You will have to do it in a loop, like this:
public static string getBetween(string strSource, string strStart, string strEnd)
{
int Start = 0, End = 0;
StringBuilder stb = new StringBuilder();
while (strSource.IndexOf(strStart, Start) > 0 && strSource.IndexOf(strEnd, Start + 1) > 0)
{
Start = strSource.IndexOf(strStart, Start) + strStart.Length;
End = strSource.IndexOf(strEnd, Start);
stb.Append(strSource.Substring(Start, End - Start));
Start++;
End++;
}
return stb.ToString();
}
solved How to find all words in a string C# [closed]