Question

I have a set of strings that contain within them one or more question marks delimited by a comma, a comma plus one or more spaces, or potentially both. So these strings are all possible:

BOB AND ?
BOB AND ?,?,?,?,?
BOB AND ?, ?, ? ,?
BOB AND ?,?  ,  ?,?
?,  ?               ,? AND BOB

I need to replace the question marks with @P#, so that the above samples would become:

BOB AND @P1
BOB AND @P1,@P2,@P3,@P4,@P5
BOB AND @P1,@P2,@P3,@P4
BOB AND @P1,@P2,@P3,@P4
@P1,@P2,@P3 AND BOB

What’s the best way to do this without regex or Linq?

Answer 1

I ignored the trimming of spaces in your output example, because if this is to be used in a SQL statement, the spaces are irrelevent. This should perform pretty well due to the use of StringBuilder rather than repeated calls to Replace, Substring, or other string methods.:

public static string GetParameterizedString(string s)
{
    var sb = new StringBuilder();
    var sArray = s.Split('?');
    for (var i = 0; i < sArray.Length - 1; i++)
    {
        sb.Append(sArray[i]);
        sb.Append("@P");
        sb.Append(i + 1);
    }
    sb.Append(sArray[sArray.Length - 1]);
    return sb.ToString();
}