how to Sending SMS through VB.NET

Question

I tried to send sms
it was using textlocal.in
this is the code i tried

Public Function SendSms(sender As Object, e As EventArgs) Handles Button1.Click
    Dim apikey = txtAPI.Text
    Dim message = txtMsg.Text
    Dim numbers = txtNum.Text
    Dim strPOST As String
    Dim senderName = txtSend.Text
    Dim url As String = "https://api.textlocal.in/send/?"

    strPOST = url + "apikey=" + apikey _
    + "&numbers=" + numbers _
    + "&message=" + WebUtility.UrlEncode(message) _
    + "&sender=" + sender

    Dim request As WebRequest = WebRequest.Create(strPOST)
    request.Method = "POST"
    Dim byteArray As Byte() = Encoding.UTF8.GetBytes(strPOST)
    request.ContentType = "application/x-www-form-urlencoded"
    request.ContentLength = byteArray.Length
    Dim dataStream As Stream = request.GetRequestStream()
    dataStream.Write(byteArray, 0, byteArray.Length)
    dataStream.Close()

    Dim response As WebResponse = request.GetResponse()
    dataStream = response.GetResponseStream()
    Dim reader As New StreamReader(dataStream)
    Dim responseFromServer As String = reader.ReadToEnd()
    Console.WriteLine(responseFromServer)
    Console.ReadLine()

    reader.Close()
    dataStream.Close()
    response.Close()

    If responseFromServer.Length > 0 Then
        Return responseFromServer
    Else
        Return CType(response, HttpWebResponse).StatusDescription
    End If
End Function

it is saying Operator '+' is not defined for string " https://api.textlocal.in/send/?a " and type 'Button

Answer 1

In this code sender is the Button that raises the event:

Public Function SendSms(sender As Object
                        ^^^^^^

It is not the phone number of the person sending the message. Replace sender with senderName on this line:

strPOST = url + "apikey=" + apikey _
+ "&numbers=" + numbers _
+ "&message=" + WebUtility.UrlEncode(message) _
+ "&sender=" + sender
               ^^^^^^^

Do not use + to concatenate strings in vb unless you know exactly what it is doing

Use & to concatenate strings, but in this case I would recommend you use string formatting