Develop Reference

i have a switch statement but i dont know how to change it to how i need it

I have a switch statement where the first case is "" as I want to check if the string is empty. My problem is that I need another case which is able to check if there is something within the variable, 'sName', but I don't know how to write this out.
You can ignore what is within the cases but the case in bold that contains dashes is the one I need changing.
(relevant code)
string sName = "";
int iChoice = 0;
switch (sName)
{
case "":
Console.Clear();
Console.WriteLine("You are not yet logged in, would you like to create a new account?\n");
Console.WriteLine("------------------------------------------------------------------------------------------------------------------");
Console.WriteLine("PLEASE NOTE: IF YOU ATTEMPT TO CREATE A NEW ACCOUNT WITH AN EXISTING NAME, YOUR PREVIOUS DATA WILL BE OVERWRITTEN!");
Console.WriteLine("------------------------------------------------------------------------------------------------------------------");
Console.WriteLine("\n1. Create a new account");
Console.WriteLine("2. Login");
iChoice = Convert.ToInt32(Console.ReadLine());
switch (iChoice)
{
case 1:
//outputs text to the console
Console.Write("What is your name? ");
//stores user input into variable sName
sName = Console.ReadLine();
//outputs text to the console
Console.Write("\nWhich school do you work at? ");
//stores user input into variable sSchool
sSchool = Console.ReadLine();
//outputs text to the console
Console.Write("\nWhat class do you teach? ");
//stores user input into variable sClass
sClass = Console.ReadLine();
//outputs the user's name
Console.WriteLine("\nYou are now logged in as " + sName + "\n");
//creates a new text file using the users name
using (StreamWriter sw = new StreamWriter(sName + ".txt"))
{
//writes to the text file using the variables
sw.WriteLine(sName);
sw.WriteLine(sSchool);
sw.WriteLine(sClass);
}
Console.Clear();
displayMenu();
iOption = Convert.ToInt32(Console.ReadLine());
break;
case 2:
//outputs text to the console
Console.Write("What is your name? ");
//stores user input into variable sName
sName = Console.ReadLine();
Console.Clear();
displayMenu();
iOption = Convert.ToInt32(Console.ReadLine());
break;
}
Console.ReadKey();
Console.Clear();
displayMenu();
iOption = Convert.ToInt32(Console.ReadLine());
break;
***case --------------------------------:***
{
Console.Clear();
Console.WriteLine("You are already logged in as " + sName);
Console.WriteLine("You are not yet logged in, would you like to create a new account?\n");
Console.WriteLine("------------------------------------------------------------------------------------------------------------------");
Console.WriteLine("PLEASE NOTE: IF YOU ATTEMPT TO CREATE A NEW ACCOUNT WITH AN EXISTING NAME, YOUR PREVIOUS DATA WILL BE OVERWRITTEN!");
Console.WriteLine("------------------------------------------------------------------------------------------------------------------");
Console.WriteLine("\n1. Create a new account");
Console.WriteLine("2. Login");
iChoice = Convert.ToInt32(Console.ReadLine());

It sounds like you dont need to use a switch, "If" should be good enough

If all you want to do is perform two different actions depending on whether sName contains an empty string or not, then I wouldn't use switch/case at all. if/else is made for the job:
if( sName == "" ) {
// sName is empty
} else {
// sName is not empty
}
If you do want to use a switch for some reason, you'd use default for the non-empty condition, like this:
switch( sName ) {
case "":
// sName is empty
break;
default:
// sName is not empty
break;
}
Either way will do exactly the same thing, but as you can see the if/else is quite a bit simpler.

How to know what user starts program?

I write simple program, that starts another Client.exe from user:
Console.Write("Enter your domain: ");
string domain = Console.ReadLine();
Console.Write("Enter you user name: ");
string uname = Console.ReadLine();
Console.Write("Enter your password: ");
SecureString password = new SecureString();
ConsoleKeyInfo key;
do
{
key = Console.ReadKey(true);
// Ignore any key out of range.
if (((int)key.Key) >= 33 && ((int)key.Key <= 90) && key.Key != ConsoleKey.Enter)
{
// Append the character to the password.
password.AppendChar(key.KeyChar);
Console.Write("*");
}
// Exit if Enter key is pressed.
} while (key.Key != ConsoleKey.Enter);
Console.WriteLine();
try
{
Console.WriteLine("\nTrying to launch ProcessClient using your login information...");
Process.Start("ProcessClient.exe", uname, password, domain);
}
catch (Win32Exception ex)
{
Console.WriteLine(ex.Message);
}
And it works! But how Client.exe knows what user execute this program?

You can know this using the Environment class:
Environment.UserName
Gets the user name of the person who is currently logged on to the Windows operating system.
Environment.UserDomainName
Gets the network domain name associated with the current user.

Prevent empty console input from user in c#

Hi I would like to prevent users from entering nothing in the input field.
I've tried using an if else but the console keeps crashing when there's no input. (for both user input and ldap address input ==> I want it to show "No input detected." and allow the user to re-enter the username)
And if I used (results == " "), I would get a error:
"Operator '==' cannot be applied to operands of type
'System.DirectoryServices.SearchResult' and 'string'"
Is there any way for me to resolve this? The codes are as shown below.
Affected codes from line 16 onwards (for the top block of codes)
if (results != null)
{
//Check is account activated
bool isAccountActived = IsActive(results.GetDirectoryEntry());
if (isAccountActived)
Console.WriteLine(targetUserName + "'s account is active.");
else
Console.WriteLine(targetUserName + "'s account is inactive.");
//Check is account expired or locked
bool isAccountLocked = IsAccountLockOrExpired(results.GetDirectoryEntry());
if (isAccountLocked)
Console.WriteLine(targetUserName + "'s account is locked or has expired.");
else
Console.WriteLine(targetUserName + "'s account is not locked or expired.");
Console.WriteLine("\nEnter bye to exit.");
Console.WriteLine("Press any key to continue.\n\n");
}
else if (results == " ")
{
//no user entered
Console.WriteLine("No input detected!");
Console.WriteLine("\nEnter bye to exit.");
Console.WriteLine("Press any key to continue.\n");
}
else
{
//user does not exist
Console.WriteLine("User not found!");
Console.WriteLine("\nEnter bye to exit.");
Console.WriteLine("Press any key to continue.\n");
}
If it helps, I've attached the whole code below.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.DirectoryServices;
using System.DirectoryServices.AccountManagement;
using System.Net;
using System.Net.Sockets;
using System.Net.NetworkInformation;
using System.Data.SqlClient;
namespace ConsoleApplication2
{
class Program
{
const String serviceAccountUserName = "mobileuser1";
const String serviceAccountPassword = "password123$";
const int UF_LOCKOUT = 0x0010;
const int UF_PASSWORD_EXPIRED = 0x800000;
static void Main(string[] args)
{
string line;
Console.WriteLine("Welcome to account validator V1.0.\n"+"Please enter the ldap address to proceed.");
Console.Write("\nEnter address: ");
String ldapAddress = Console.ReadLine();
try
{
if (ldapAddress != null)
{
Console.WriteLine("\nQuerying for users in " + ldapAddress);
//start of do-while
do
{
Console.WriteLine("\nPlease enter the user's account name to proceed.");
Console.Write("\nUsername: ");
String targetUserName = Console.ReadLine();
bool isValid = false;
using (PrincipalContext pc = new PrincipalContext(ContextType.Domain, ldapAddress))
{
// validate the credentials
isValid = pc.ValidateCredentials(serviceAccountUserName, serviceAccountPassword);
// search AD data
DirectoryEntry entry = new DirectoryEntry("LDAP://" + ldapAddress, serviceAccountUserName, serviceAccountPassword);
//create instance fo the directory searcher
DirectorySearcher desearch = new DirectorySearcher(entry);
//set the search filter
desearch.Filter = "(&(sAMAccountName=" + targetUserName + ")(objectcategory=user))";
//find the first instance
SearchResult results = desearch.FindOne();
if (results != null)
{
//Check is account activated
bool isAccountActived = IsActive(results.GetDirectoryEntry());
if (isAccountActived) Console.WriteLine(targetUserName + "'s account is active.");
else Console.WriteLine(targetUserName + "'s account is inactive.");
//Check is account expired or locked
bool isAccountLocked = IsAccountLockOrExpired(results.GetDirectoryEntry());
if (isAccountLocked) Console.WriteLine(targetUserName + "'s account is locked or has expired.");
else Console.WriteLine(targetUserName + "'s account is not locked or expired.");
Console.WriteLine("\nEnter bye to exit.");
Console.WriteLine("Press any key to continue.\n\n");
}
else if (results == " ")
{
//no user entered
Console.WriteLine("No input detected!");
Console.WriteLine("\nEnter bye to exit.");
Console.WriteLine("Press any key to continue.\n");
}
else
{
//user does not exist
Console.WriteLine("User not found!");
Console.WriteLine("\nEnter bye to exit.");
Console.WriteLine("Press any key to continue.\n");
}
}//end of using
}//end of do
//leave console when 'bye' is entered
while ((line = Console.ReadLine()) != "bye");
}//end of if for ldap statement
else if (ldapAddress == " ")
{
Console.WriteLine("No input detected.");
Console.ReadLine();
Console.WriteLine("\nEnter bye to exit.");
Console.ReadLine();
Console.WriteLine("Press any key to continue.\n");
Console.ReadLine();
}
else
{
Console.WriteLine("Address not found!");
Console.ReadLine();
Console.WriteLine("\nEnter bye to exit.");
Console.ReadLine();
Console.WriteLine("Press any key to continue.\n");
Console.ReadLine();
}
}//end of try
catch (Exception e)
{
Console.WriteLine("Exception caught:\n\n" + e.ToString());
}
} //end of main void
static private bool IsActive(DirectoryEntry de)
{
if (de.NativeGuid == null) return false;
int flags = (int)de.Properties["userAccountControl"].Value;
return !Convert.ToBoolean(flags & 0x0002);
}
static private bool IsAccountLockOrExpired(DirectoryEntry de)
{
string attribName = "msDS-User-Account-Control-Computed";
de.RefreshCache(new string[] { attribName });
int userFlags = (int)de.Properties[attribName].Value;
return userFlags == UF_LOCKOUT || userFlags == UF_PASSWORD_EXPIRED;
}
}
}

You should put the ReadLine in a loop.
string UserName = "";
do {
Console.Write("Username: ");
UserName = Console.ReadLine();
if (!string.IsNullOrEmpty(UserName)) {
Console.WriteLine("OK");
} else {
Console.WriteLine("Empty input, please try again");
}
} while (string.IsNullOrEmpty(UserName));
You basically repeat the prompt over and over until the string entered by the user is no longer null or empty.
Best method would probably be to create a new function to get a non empty input:
private static string GetInput(string Prompt)
{
string Result = "";
do {
Console.Write(Prompt + ": ");
Result = Console.ReadLine();
if (string.IsNullOrEmpty(Result)) {
Console.WriteLine("Empty input, please try again");
}
} while (string.IsNullOrEmpty(Result));
return Result;
}
You can then just use the function to get your inputs like:
static void Main(string[] args)
{
GetInput("Username");
GetInput("Password");
}
Result:

Try using the code :
(!string.IsNullOrEmpty(input));

This is user first name and last name string
//Make container for the user first name and last name
string myFirstName = "";
string myLastName = "";
//Do while loop
do
{
//Welcomes user to the app and asks for first name then asks for last name
Console.WriteLine("Welcome");
Console.WriteLine("Enter first name: ");
//Takes users first name and last name and saves it in myFirstName and myLastName
myFirstName = Console.ReadLine();
Console.Write("Enter Last name: ");
myLastName = Console.ReadLine();
Console.WriteLine();
//If the first AND (&&) last name is not empty because the user entered first name and last name then display the hello message
if (!string.IsNullOrEmpty(myFirstName) && !string.IsNullOrEmpty(myLastName))
{
Console.WriteLine("Hello " + myFirstName + " " + myLastName + " hope you enjoy your day");
}
else //Else the first name or last name is left empty then display the error message
{
Console.WriteLine("Please enter your first name and last name");
Console.WriteLine();
}
//While if either the first name OR (||) last name is empty then keep asking the user for input
} while (string.IsNullOrEmpty(myFirstName) ||
string.IsNullOrEmpty(myLastName));
Console.ReadLine();
Output:

Issues with comparing .ToString()

so I'm making a mock program just to get somewhat more used to c# and heres what i've got:
ConsoleKeyInfo Input;
StringBuilder sb = new StringBuilder();
const string Password = "class";
Console.Write("Input Your Password: ");
do
{
Input = Console.ReadKey(true);
sb.Append(Input.KeyChar);
} while (Input.Key != ConsoleKey.Enter);
Console.WriteLine();
if (sb.ToString() == Password)
{
Console.WriteLine("Correct Password!");
}
Console.WriteLine("You Entered: " + sb.ToString());
Console.WriteLine("The Pass is: " + Password);
Console.ReadLine();
But I have an issue with my if-statement when I come to compare sb.ToString() and Password. Although if you put the same thing in as Password the if-statement still doesn't become true.
Why is this?

Because you are also adding the Enter key to StringBuilder at the end, you can just check it before adding:
do
{
Input = Console.ReadKey(true);
if(Input.Key != ConsoleKey.Enter)
sb.Append(Input.KeyChar);
} while (Input.Key != ConsoleKey.Enter);
Or instead of checking it twice you can also refactor your loop like this:
while ((Input = Console.ReadKey(true)).Key != ConsoleKey.Enter)
sb.Append(Input.KeyChar);

Create a stream reader in c# console to read only one student at a time instead of all of them using a .txt file

class Program
{
static string strFile = "Student Database.txt";
static void Main(string[] args)
{
string strInput = null; // user input string
start:
System.IO.DirectoryInfo dir = new DirectoryInfo("student_results.txt");
// Request user input as to actions to be carried out
Console.WriteLine("\nWhat do you want to do?\n" +
" 1.View Student(s)\n 2.Add a New Student\n 3.Exit program");
// Save user input to make decision on program operation
strInput = Console.ReadLine();
// Switch statement checking the saved user input to decide the action
// to be carried out
switch (strInput)
{
case "1": // choice for view file
Console.Clear();
string file = AppDomain.CurrentDomain.BaseDirectory +
#"student_results.txt";
StreamReader sr = new StreamReader(file);
string wholeFile = sr.ReadToEnd();
Console.Write(wholeFile + "");
sr.Close();
goto start;
...
}
...
}
...
}
I want this part of my code to just read the students indivially and relay them back to me, instead of how it is doing so at the moment were it just calls all of them back to me when I press '1) view Student' it pretty much says "please enter the students name or ID number of which student you would like to view".
I've currently have got the ID number running off a random number generator.
Thank you for your time guys.

Welcome to SO, first of all goto is not a good choice in C# in 99% of cases, and you'd better use loops. For your code I would save each student in a single line and at the time of reading students I would read them line by line untill I found the student.
class Program
{
static string strFile = "Student Database.txt";
static void Main(string[] args)
{
string strInput = ""; // user input string
while (strInput != "3")
{
System.IO.DirectoryInfo dir = new System.IO.DirectoryInfo("student_results.txt");
Console.WriteLine("\nWhat do you want to do?\n 1.View Student(s)\n 2.Add a New Student\n 3.Exit program"); // request user input as to actions to be carried out
strInput = Console.ReadLine(); //save user input to make decision on program operation
switch (strInput)
{
case "1":
Console.Clear();
Console.WriteLine("Enter Student ID: \n");
string file = AppDomain.CurrentDomain.BaseDirectory + #"student_results.txt";
StreamReader sr = new StreamReader(file);
string StudentID = Console.ReadLine();
string line = "";
bool found = false;
while((line = sr.ReadLine()) != null)
{
if (line.Split(',')[0] == StudentID)
{
found = true;
Console.WriteLine(line);
break;
}
}
sr.Close();
if (!found)
{
Console.WriteLine("Not Found");
}
Console.WriteLine("Press a key to continue...");
Console.ReadLine();
break;
case "2":
Console.WriteLine("Enter Student ID : ");
string SID = Console.ReadLine();
Console.WriteLine("Enter Student Name : ");
string SName = Console.ReadLine();
Console.WriteLine("Enter Student Average : ");
string average = Console.ReadLine();
string wLine = SID + "," +SName+":"+average;
file = AppDomain.CurrentDomain.BaseDirectory + #"student_results.txt";
StreamWriter sw = File.Exists(file) ? File.AppendText(file) : new StreamWriter(file);
sw.WriteLine(wLine);
sw.Close();
Console.WriteLine("Student saved on file, press a key to continue ...");
Console.ReadLine();
Console.Clear();
break;
case "3":
return;
default:
Console.Clear();
Console.WriteLine("Invalid Command!\n");
break;
}
}
}
}
this code might not be complete, I wanted to give you the idea, I hope it helps.

Presuming you are not dealing with a huge file of students, and on the basis that you want to make multiple queries, i would not read the text file line by line each time.
Instead create a student class, read the file once on init, and create a list< student > from the data. Then you can query it with LinQ

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
namespace ReadStudents
{
class Program
{
static string _filename = "students.txt";
static void Main(string[] args)
{
List<Student> students = new List<Student>();
// Load students.
StreamReader reader = new StreamReader(_filename);
while (!reader.EndOfStream)
students.Add( new Student( reader.ReadLine()));
reader.Close();
string action;
bool showAgain = true;
do
{
Console.WriteLine("");
Console.WriteLine("1. See all students.");
Console.WriteLine("2. See student by ID.");
Console.WriteLine("3. Add new student.");
Console.WriteLine("0. Exit.");
Console.WriteLine("");
action = Console.ReadLine();
switch (action)
{
case "1":
foreach (Student item in students)
item.Show();
break;
case "2":
Console.Write("ID = ");
int id = int.Parse( Console.ReadLine() ); // TODO: is valid int?
foreach (Student item in students)
if (item.Id == id)
item.Show();
break;
case "3":
Console.WriteLine("ID-Name");
Student newStudent = new Student(Console.ReadLine());
students.Add(newStudent);
StreamWriter writer = new StreamWriter(_filename, true);
writer.WriteLine(newStudent);
writer.Close();
break;
case "0":
Console.WriteLine("Bye!");
showAgain = false;
break;
default:
Console.WriteLine("Wrong action!");
break;
}
}
while (showAgain);
}
}
class Student
{
public int Id;
public string Name;
public Student(string line)
{
string[] fields = line.Split('-');
Id = int.Parse(fields[0]);
Name = fields[1];
}
public void Show()
{
Console.WriteLine(Id + ". " + Name);
}
}
}
I assume your data are in "ID-Name" format for example:
1-Alexander
2-Brian
3-Christian
I load file line-by-line and pass to Student class which converts in constructor text data to more friendly form. Next, application shows interface until user write "0".