How to find certain words inside a string in C#

Question

For example:

string query = "INSERT INTO Recibos (idRecibo, DataRecibo, NomeCliente, Valor, CPFCliente, EnderecoCliente, NumeroCliente, BairroCliente, Importancia, Referente, Cidade, UF, Emitente, EnderecoEmitente, NumeroEmitente, BairroEmitente, CPFEmitente, RG) VALUES (" +
                        "@idRecibo," +
                        "@dataRecibo," +
                        "@nomeCliente," +
                        "@valor," +
                        "@cpfCliente," +
                        "@endCliente," +
                        "@numCliente," +
                        "@baiCliente," +
                        "@importancia," +
                        "@referente, +" +
                        "@cidade," +
                        "@uf," +
                        "@emitente," +
                        "@endEmitente," +
                        "@numEmitente," +
                        "@baiEmitente," +
                        "@cpfEmitente," +
                        "@rg)";

I would like to make a method that can scan the entire string and return to me all the words that are preceded by the @ symbol (with it included).

Answer 1

From the comment you made in @Catarina Batista’s reply, I understood that you would like to create a custom method to search all the parameters of your query and then customize it your way.

I made a method based on your description, but I can’t tell you if it’s done right.

public static List<string> ReturnAllParameters(string query)
{
    var parameterName = new StringBuilder();
    var parameters = new List<string>();

    for (int i = 0; i < query.Length; i++)
    {
        if (query[i] == '@')
        {
            do
            {
                parameterName.Append(query[i]);
                i++;
            } while (char.IsLetterOrDigit(query[i]));

            parameters.Add(parameterName.ToString());
            parameterName.Clear();
        }
    }

    return parameters;
}

Then call the method and you will get a list of string with all parameters of your query.

var parameters = ReturnAllParameters(query);

Answer 2

Friend, I believe that if performance is a concern of yours, it would be more interesting - and succinct - to use a Regex for this search.

The @Pedro Paulo response is interesting, but it uses several processes that can be optimized with the use of Regex.

    static List<string> BuscarPalavras(string consulta, string regex = @"(?<!\w)@\w+")
    {
        var resultado = new List<string>(); 
        foreach (Match match in Regex.Matches(consulta, regex))
            resultado.Add(match.Value);

        return resultado;
    }

Each if and for removed are less complexity in the application. This way the function has two entries, its query and the regex standard that already comes with default value becoming an optional parameter, but that can be modified to search for other types of words. And an output value only, in case the word list.

If you have difficulty with Regex, you can play the value that is in the code on Regex101 that he’ll explain to you what he’s doing in more detail, and you can even modify it.

Answer 3

I was a little confused about your question, but if you are referring to replacing these parameters with variables it is, (with mysql):

static public MySqlCommand Command { get; set; }


Command.Parameters.AddWithValue("@idRecibo", nomeVariavel);