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NullReferenceException? Why? [closed]

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I try to calculate the total collective age of my passengers in calc_total_age() this works before I add a passenger and writes out "0". However when I add a passenger I get NullReferenceException, I have tried different things but I just can't wrap my head around what I'm doing. I need a little shove in the right direction and maybe and explanation of what the he** I am doing and I don't know what my GetAge() does either really I have tried to call it but it doesn't seem to work.
This is all my code:
using System;
using System.Linq;
using System.Text;
using System.Collections.Generic;
using System.Threading.Tasks;
class Program {
public static void Main (string[] args) {
//Console.Clear();
Console.WriteLine("Hi, welcome to the Buss-Simulator!");
Console.ReadKey();
var mybus = new Bus();
mybus.Run();
Console.ReadKey();
}
}
using System;
using System.Linq;
using System.Text;
using System.Collections.Generic;
using System.Threading.Tasks;
class Bus {
public int total_passengers = 0;
public Passenger[] info_passengers;
public int totalAge = 0;
public int totalSeats = 25;
public void Run()
{
info_passengers = new Passenger[25];
string [] menu = new string[]{"1. Pick up passenger.", "2. Show who's on the bus.", "3. Calculate total age of passengers"};
int MenuSelect = 0;
while (true)
{
Console.Clear();
Console.WriteLine("What do you want to do?");
Console.WriteLine();
Console.CursorVisible = false;
if (MenuSelect == 0)
{
Console.WriteLine(menu[0] + " ⭅");
Console.WriteLine(menu[1]);
Console.WriteLine(menu[2]);
}
else if(MenuSelect == 1)
{
Console.WriteLine(menu[0]);
Console.WriteLine(menu[1] + " ⭅");
Console.WriteLine(menu[2]);
}
else if(MenuSelect == 2)
{
Console.WriteLine(menu[0]);
Console.WriteLine(menu[1]);
Console.WriteLine(menu[2] + " ⭅");
}
var keyPressed = Console.ReadKey();
if(keyPressed.Key == ConsoleKey.DownArrow && MenuSelect != menu.Length -1)
{
MenuSelect++;
}
else if (keyPressed.Key == ConsoleKey.UpArrow && MenuSelect >= 1)
{
MenuSelect--;
}
else if (keyPressed.Key == ConsoleKey.Enter)
{
switch (MenuSelect)
{
case 0:
add_passengers();
break;
case 1:
print_passengers();
break;
case 2:
calc_total_age();
break;
}
}
}
}
public void add_passengers()
{
if (total_passengers == 25)
{
Console.WriteLine("\nBus is full!");
System.Threading.Thread.Sleep(2000);
return;
}
try
{
Console.WriteLine("\nType the name, age & gender of your passenger.");
Console.Write("\nName: ");
string name = Console.ReadLine();
Console.Write("\nAge: ");
int age = Convert.ToInt32(Console.ReadLine());
Console.Write("\nGender: ");
string gender = Console.ReadLine();
Passenger passenger = new Passenger(aName: name, aAge: age, aGender: gender);
Array.Resize(ref info_passengers, info_passengers.Length + 1);
info_passengers[info_passengers.Length - 1] = passenger;
}
catch (Exception e)
{
Console.WriteLine("\nFollow instructions.");
System.Threading.Thread.Sleep(2000);
return;
}
total_passengers++;
Console.WriteLine("You boarded 1 Passenger." + "\nThere are " + (totalSeats - total_passengers) + " seats left.");
System.Threading.Thread.Sleep(2000);
return;
}
public void print_passengers()
{
Console.WriteLine();
foreach (var i in info_passengers)
{
Console.WriteLine(i);
}
Console.ReadKey();
}
public void calc_total_age()
{
for (int i = 0; i < total_passengers; i++)
{
totalAge += info_passengers[i].age;
}
Console.WriteLine(totalAge);
Console.ReadKey();
}
}
using System;
using System.Linq;
using System.Text;
using System.Collections.Generic;
using System.Threading.Tasks;
class Passenger{
public string name;
public int age;
public string gender;
public Passenger(string aName, int aAge, string aGender)
{
name = aName;
age = aAge;
gender = aGender;
}
public override string ToString()
{
return string.Format($"This is {name}, {gender}, {age} years old.");
}
public int GetAge()
{
return age;
}
}

you don't need to resize info_passengers array since it is enough for total passangers. When you add an extra array cell, you add a passanger to the end of arry, but you still have the empty cells in the beginnig of array with null that are causing the exception.
so remove this code
Array.Resize(ref info_passengers, info_passengers.Length + 1);
and fix this
total_passengers++;
info_passengers[ total_passengers-1] = passenger;
and don't forget to remove total_passengers++; from here
Console.WriteLine("You boarded 1 Passenger." + "\nThere are " + (totalSeats - total_passengers) + " seats left.");
and add totalAge=0 in calc_total_age
public void calc_total_age()
{
totalAge=0;
for (int i = 0; i < total_passengers; i++)
{
totalAge += info_passengers[i].age;
}
and it is not a very good idea to hide errors in your catch blok. I would make it
catch (Exception e)
{
Console.WriteLine("\n Error!!! " + e.Message);
System.Threading.Thread.Sleep(2000);
return;
}

The answer to this one is very simple!
You declare:
public Passenger[] info_passengers;
This actually creates a pointer to a Passenger array, which (like all pointers) is initially null. It does not create the actual array itself.
When your code comes to call:
Array.Resize(ref info_passengers, info_passengers.Length + 1);
the method Resize expects the array parameter to point to an array. However, info_passengers is still null. So you get the exception.
I think all you need to do is to initialise info_passengers to an new empty array, like this:
public Passenger[] info_passengers = new Passenger[]();
and then I think it'll all work.

How to determine input when the can have a variable?

I'm working on this commandline based dice. And I want it to be able to output statistics and reset those internal statistics. Currently I have the following classes: Dice and DiceInterface.
I want the user to be able to use the following format for input: "'Throw' to throw the dice, alternate use 'Throw(x)', 'Stat(side)' to see how many times (side) has been thrown, or 'Reset' to reset thrown statistics"
I need a way to determine if the user has typed Throw, Throw(x), Stat(side) or Reset. Throw and Reset are obvious to me but I find it quite difficult to imagine a way to do Throw(x) and Stat(side). Does anyone have any tips or a solution?
Thanks in advance!
using System;
using System.Collections.Generic;
using System.Text;
namespace Oefening_2
{
class DiceInterface
{
static void Main()
{
StartProgram();
}
static void StartProgram()
{
Console.WriteLine("Hello, how many sides would you like the dice to have?");
var input = Console.ReadLine();
if (Int32.TryParse(input, out int number))
{
int desiredSides = number;
Dice NewDice = new Dice(desiredSides);
Console.WriteLine("What would you like to do? ");
Console.WriteLine("Type: 'Throw' to throw the dice, alternate use 'Throw(x)', 'Stat(side)' to see how many times (side) has been thrown, or 'Reset' to reset thrown statistics");
MainIO(NewDice);
}
else
{
Console.WriteLine("That is not an integer! The program will restart now...");
StartProgram();
}
}
static void MainIO(Dice CurrentDice)
{
Console.Write("Input: ");
string input = Console.ReadLine();
//Throw
if (input == "Throw")
{
Console.WriteLine(CurrentDice.Throw());
MainIO(CurrentDice);
}
//Throw(x)
else if(input == "")
//Thrown(side)
//Reset
else if (input == "Reset")
{
CurrentDice.ResetStatistics();
MainIO(CurrentDice);
}
}
}
}
using System;
namespace Oefening_2
{
class Dice
{
public int Sides { get; set; }
private readonly Random _rnd = new Random();
public int[] Thrown;
public Dice(int sides)
{
Sides = sides;
Thrown = new int[sides--];
}
public Dice():this(6)
{
}
public int Throw()
{
int thrownNumber = _rnd.Next(1, Sides);
Thrown[thrownNumber]++;
return thrownNumber;
}
public int NrOfTimesThrown(int side)
{
int result;
result = Thrown[side];
return result;
}
public void ResetStatistics()
{
for(int i = 0 ; i < Sides; i++)
{
Thrown[i] = 0;
}
}
}
}

This can be fairly simply done with StartsWith to check if a string starts with some prefix, and use .Remove to get anything after this prefix:
if(input.StartsWith("Stat"){
var parameterString = input.Remove(0, "Stat".Length);
if(int.TryParse(parameterString , out var side){
...
}
}

If I correctly understood your problem, it could be solved with an approach like this:
Console.WriteLine("Enter a value");
var s = Console.ReadLine();
if(s.Contains('('))
{
int pFrom = s.IndexOf("(");
int pTo = s.LastIndexOf(")");
var myChoice = s.Substring(0, pFrom);
var myValue = s.Substring(pFrom + 1, pTo - pFrom);
Console.WriteLine($"You choosed : {myChoice}");
Console.WriteLine($"With a value of: {myValue}");
}
This is just a brief example of how to "understand" if there is a value and then recover it.
I hope this could help you somehow.

C# How can i use parameter function in my hangman game

I have been asked by my teacher to store my functions inside a parameter driven function and replacing the switch with an if statement. I have no idea how i am supposed to do this. Any help is appreciated.
using System;
using System.Collections.Generic;
using System.Collections;
using System.Linq;
using System.Text;
namespace ConsoleApplication6
{
class Hangman
{
public static int lives = 5;
static string[] wordBank = { "study", "cat", "dress", "shoes", "lipstick" };
static ArrayList wordList = new ArrayList(wordBank);
static void Main(string[] args)
{
Console.ForegroundColor = ConsoleColor.Green;
Console.Title = "C# Hangman";
Console.WriteLine("Hang man!");
string response = "";
do
{
Console.Write("Enter Command (1. Add Words, 2. List Words , 3. Play , 4. Exit) Pick 1-4: ");
response = Console.ReadLine();
switch (response)
{
case "1":
AddWord();
break;
case "2":
ListWords();
break;
case "3":
Play();
break;
case "4":
break;
}
} while (response != "4");
}
static void AddWord()
{
Console.Write("Enter the word to add: ");
String temp = Console.ReadLine();
wordList.Add(temp);
Console.WriteLine("{0} was added to the dictionary!", temp);
}
static void ListWords()
{
foreach (Object obj in wordList)
Console.WriteLine("{0}", obj);
Console.WriteLine();
}
static void AskLives()
{
try
{
Console.WriteLine("please enter number of lives?");
lives = int.Parse(Console.ReadLine());
}
catch
{
AskLives();
}
}
static void Play()
{
Random random = new Random((int)DateTime.Now.Ticks);
string wordToGuess = wordList[random.Next(0, wordList.Count)].ToString();
string wordToGuessUppercase = wordToGuess.ToUpper();
StringBuilder displayToPlayer = new StringBuilder(wordToGuess.Length);
for (int i = 0; i < wordToGuess.Length; i++)
displayToPlayer.Append('-');
List<char> correctGuesses = new List<char>();
List<char> incorrectGuesses = new List<char>();
bool won = false;
int lettersRevealed = 0;
string input;
char guess;
AskLives();
while (!won && lives > 0)
{
Console.WriteLine("Current word: " + displayToPlayer);
Console.Write("Guess a letter: ");
input = Console.ReadLine().ToUpper();
guess = input[0];
if (correctGuesses.Contains(guess))
{
Console.WriteLine("You've already tried '{0}', and it was correct!", guess);
continue;
}
else if (incorrectGuesses.Contains(guess))
{
Console.WriteLine("You've already tried '{0}', and it was wrong!", guess);
continue;
}
if (wordToGuessUppercase.Contains(guess))
{
correctGuesses.Add(guess);
for (int i = 0; i < wordToGuess.Length; i++)
{
if (wordToGuessUppercase[i] == guess)
{
displayToPlayer[i] = wordToGuess[i];
lettersRevealed++;
}
}
if (lettersRevealed == wordToGuess.Length)
won = true;
}
else
{
incorrectGuesses.Add(guess);
Console.WriteLine("Nope, there's no '{0}' in it!", guess);
lives--;
}
Console.WriteLine(displayToPlayer.ToString());
}
if (won)
Console.WriteLine("You won!");
else
Console.WriteLine("You lost! It was '{0}'", wordToGuess);
Console.Write("Press ENTER to exit...");
Console.ReadLine();
}
}
}

Highlight the switch block and select "Quick Actions."
Rename the function after applying the change.

Error 1 Cannot implicitly convert type 'int**' to 'int*'. An explicit conversion exists (are you missing a cast?)

I'm learning C and C# and this question is for C#. I looking at pointers at msdn and this code is not compiling, it gives the error:Error 1 Cannot implicitly convert type int** to int*. An explicit conversion exists (are you missing a cast?). What am I missing here?
Here is the code:
int ix = 10;
unsafe
{
int* px1;
int* px2 = &ix; **The error is on this line**
}
EDIT:
Here is the program in its entirety:
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Management;
using System.Diagnostics;
using System.Windows.Forms;
using practice;
class Program
{
public delegate bool ThisIsTheDelegate(int number);
public delegate bool ThisIsAnotherDelegate(int number);
private static string address;
public static String Address
{
get
{
return address;
}
set
{
address = value;
}
}
static void Main()
{
int[] someArray = new int[] { 1, 2, 3, 5, 6, 7, 8, 9, 0 };
foreach (int number in someArray)
{
Console.WriteLine(number);
}
int integer = 98;
string someString = "edited";
string[] someStr = { "edited" };
String[] anotherStringSomestr = new String[] { "edited" };
var readWithLinq = from far in anotherStringSomestr
select far;
foreach (var some in readWithLinq)
{
Console.WriteLine(some);
}
Program newPro = new Program();
bool isEven1 = newPro.isEven(99);
Console.WriteLine(isEven1);
ThisIsTheDelegate newDelegate = newPro.isEven;
Console.WriteLine(newDelegate(98));
int[] numbers = { 1, 2, 3, 5, 6, 7, 8, 9 };
List<int> evenNumbers = FilterArray(numbers, newDelegate);
foreach(int integer1 in evenNumbers)
{
Console.WriteLine(integer1);
}
List<int> oddNumbers = FilterArray(numbers, isOdd);
foreach (int integer1 in oddNumbers)
{
Console.WriteLine(integer1);
}
ThisIsAnotherDelegate anotherDelegate;
anotherDelegate = number => (number % 2 == 0);
Console.WriteLine("{0} is a even number", anotherDelegate(4));
for (int i = 0; i < someString.Length; i++)
{
Console.WriteLine(someString);
}
for (int i = 0; i < someStr.Length; i++)
{
Console.WriteLine(someStr[i]);
}
Console.WriteLine(integer);
SimpleStruct structss = new SimpleStruct();
structss.DisplayX();
M.x = 1;
structss.x = 98;
Console.WriteLine(M.x);
Console.WriteLine(structss.x);
M.structtaker(ref structss);
M.classtaker();
Console.WriteLine(structss.x);
Console.WriteLine(M.x);
M.x = 1;
structss.x = 98;
int ix = 10;
unsafe
{
int* px1;
int* px2 = &ix;
}
int selection = 98;
while (selection != 0)
{
mainMenu();
Console.Write("Enter choice: ");
selection = Convert.ToInt32(Console.ReadLine());
switch (selection)
{
case 0:
break;
case 1:
openSomething();
break;
case 2:
calculator();
break;
case 3:
coolestProgramEverALive();
break;
case 4:
make_to_do_list();
break;
case 5:
add_to_do_list();
break;
case 6:
readToDoList();
break;
case 7:
linq_and_arrays();
break;
case 8:
calendar();
break;
case 9:
linq_and_collections();
break;
default:
Console.WriteLine("Unkown selection. Try again");
break;
}
}
}
private static bool isOdd(int number)
{
return (number % 2 == 1);
}
private static List<int> FilterArray(int[] numbers, ThisIsTheDelegate newDelegate)
{
List<int> result = new List<int>();
foreach (int item in numbers)
{
if (newDelegate(item))
result.Add(item);
}
return result;
}
private static void linq_and_collections()
{
List<string> names = new List<string>();
names.Add("Billy");
names.Add("Steve");
names.Add("Casandra");
names.Insert(0, "Johanna");
names.Add("Sonny");
names.Add("Suzanne");
names.Insert(2, "Sid");
var queryLinqUpper = from name in names
where (name.StartsWith("S") || name.StartsWith("B") || name.StartsWith("J"))
let namesToUpper = name.ToUpper()
orderby namesToUpper
select namesToUpper;
foreach (var linqToUpper in queryLinqUpper)
{
Console.Write(linqToUpper + " ");
}
Console.WriteLine();
M.WriteTextToConsole("Hello, world. Programming in C# is fun");
char c = 'A';
int count = 14;
String str = new String(c, count);
str.WriteTextToConsole();
M.WriteTextToConsole(str);
}
private static void calendar()
{
Application.Run(new Form1());
}
private static void readToDoList()
{
var files = from file in Directory.GetFiles(#"C:\data", "*.txt")
select file;
int number = 1;
foreach (var file in files)
{
Console.WriteLine(number + ". " + file);
number++;
}
Console.Write("What todolist do you want to read? Give me the name:");
try
{
string name = Console.ReadLine();
Address = Path.Combine(#"C:\data", name + ".txt");
TextReader inFile = new StreamReader(Address);
while (inFile.Peek() != -1)
{
string line = inFile.ReadLine();
Console.WriteLine(line);
}
inFile.Close();
}
catch (Exception ex)
{
MessageBox.Show("Exception thrown!", "Error");
Console.WriteLine(ex.ToString());
}
}
private static void linq_and_arrays()
{
int numberOfElements;
Console.WriteLine("Start by setting the int[] array.");
Console.Write("How many elements are there in your array?");
numberOfElements = Convert.ToInt32(Console.ReadLine());
int[] array = new int[numberOfElements];
for (int i = 0, j = numberOfElements; i < numberOfElements; i++, j--)
{
Console.Write("Integers left to add {0}. Enter an integer:", j);
array[i] = Convert.ToInt32(Console.ReadLine());
}
var arrayquery = from value in array
select value;
foreach (var val in arrayquery)
{
Console.WriteLine("Value from array:{0}", val);
}
}
private static void add_to_do_list()
{
Console.WriteLine("Which todolist do you want to modify?");
listToDoLists();
Console.Write("Enter name of todolist: ");
string name = Console.ReadLine();
Address = Path.Combine(#"C:\data", name + ".txt");
String tempString;
StreamWriter stream;
stream = File.AppendText(Address);
Console.Write("Enter your new ToDo: ");
tempString = Console.ReadLine();
stream.WriteLine(tempString);
stream.Close();
TextReader inFile;
inFile = new StreamReader(Address);
while (inFile.Peek() != -1)
{
string line = inFile.ReadLine();
Console.WriteLine(line);
}
inFile.Close();
}
private static void listToDoLists()
{
int filenumber = 1;
string[] filepaths = Directory.GetFiles("C:\\data\\", "*.txt");
foreach (string file in filepaths)
{
Console.WriteLine(filenumber + ". " + file);
filenumber++;
}
}
private static void make_to_do_list()
{
string path, name;
string yesOrNo;
Console.Write("Enter name of todolist: ");
name = Console.ReadLine();
path = Path.Combine(#"C:\data", name + ".txt");
TextWriter outFile = new StreamWriter(path);
labelOne: // else clause : unknown answer
Console.WriteLine("Do you want to add something to todolist.Y/N?");
yesOrNo = Console.ReadLine();
if (yesOrNo.ToLower() == "y")
{
string line;
int lines;
Console.Write("How many lines?");
lines = Convert.ToInt32(Console.ReadLine());
for (int i = 0; i < lines; i++)
{
Console.Write("Enter a line of text: ");
line = Console.ReadLine();
outFile.WriteLine(line);
}
outFile.Close();
}
else if (yesOrNo.ToLower() == "n")
{
Console.WriteLine("You can close the application now.");
}
else
{
Console.WriteLine("Unknown answer. Try again");
goto labelOne;
}
}
private static void coolestProgramEverALive()
{
System.Diagnostics.Process.Start(#"C:\Users\KristjanBEstur\Documents\Visual Studio 2012\Projects\The_coolest_program_ever_alive\The_coolest_program_ever_alive\obj\Debug\The_coolest_program_ever_alive.exe");
}
private static void calculator()
{
System.Diagnostics.Process.Start("calc");
}
private static void openSomething()
{
System.Diagnostics.Process.Start("notepad");
}
private static void mainMenu()
{
Console.WriteLine("Main Menu");
Console.WriteLine("0. Quit");
Console.WriteLine("1. OpenSomething");
Console.WriteLine("2. Calculator");
Console.WriteLine("3. coolestProgramEverAlive");
Console.WriteLine("4. Make todolist");
Console.WriteLine("5. Add to todolist");
Console.WriteLine("6. Read to do list");
Console.WriteLine("7. Linq and arrays");
Console.WriteLine("8. Calendar");
Console.WriteLine("9. Linq and collections");
}
public bool isEven(int number)
{
return (number % 2 == 0);
}
}
static class M
{
public static int x;
public static void WriteTextToConsole(this string text)
{
Console.WriteLine(text);
}
public static void structtaker(ref SimpleStruct s)
{
s.x = 5;
}
public static void classtaker()
{
M.x = 5;
}
}
class Test
{
static int value = 20;
unsafe static void F(out int* pi1, ref int* pi2) {
int i = 10;
pi1 = &i;
fixed (int* pj = &value) {
// ...
pi2 = pj;
}
}
}
struct SimpleStruct
{
public int x;
private int xval;
public int X
{
get
{
return xval;
}
set
{
if (value < 100)
xval = value;
}
}
public void DisplayX()
{
Console.WriteLine("The stored value is: {0}", X);
}
}

I wished I could replicate this it seems like a rather interesting issue. Here is the section of the standard that I believe applies to this (sorry about the formatting):
18.3 Fixed and moveable variables The address-of operator (§18.5.4) and the fixed statement (§18.6) divide variables into two categories:
Fixed variables and moveable variables. Fixed variables reside in
storage locations that are unaffected by operation of the garbage
collector. (Examples of fixed variables include local variables, value
parameters, and variables created by dereferencing pointers.) On the
other hand, moveable variables reside in storage locations that are
subject to relocation or disposal by the garbage collector. (Examples
of moveable variables include fields in objects and elements of
arrays.) The & operator (§18.5.4) permits the address of a fixed
variable to be obtained without restrictions. However, because a
moveable variable is subject to relocation or disposal by the garbage
collector, the address of a moveable variable can only be obtained
using a fixed statement (§18.6), and that address remains valid only
for the duration of that fixed statement. In precise terms, a fixed
variable is one of the following: • A variable resulting from a
simple-name (§7.6.2) that refers to a local variable or a value
parameter, unless the variable is captured by an anonymous function.
• A variable resulting from a member-access (§7.6.4) of the form V.I,
where V is a fixed variable of a struct-type. • A variable resulting
from a pointer-indirection-expression (§18.5.1) of the form *P, a
pointer-member-access (§18.5.2) of the form P->I, or a
pointer-element-access (§18.5.3) of the form P[E]. All other variables
are classified as moveable variables. Note that a static field is
classified as a moveable variable. Also note that a ref or out
parameter is classified as a moveable variable, even if the argument
given for the parameter is a fixed variable. Finally, note that a
variable produced by dereferencing a pointer is always classified as a
fixed variable.
I spend some time trying to create a similar error but wasn't about to. The only way I was able to recreate the issue was with the following code:
void test() {
int ix = 10;
unsafe {
int* px1 = &ix;
int* px2 = &px1; // **The error is on this line**
}
}
Of course this code cannot be fixed by moving the ix declaration into the safe scope. Perhaps you could try replicating the original problem in a very small bit of code (like above) and verify that both the problem and the fix replicate. Perhaps VS became confused. I have had problems that made no sense and went away by exiting VS and restarting (not often but a few times).

I moved the i declaration down inside the unsafe block and it fixed it, I don't know why?
Here is the code:
unsafe
{
int ix = 10;
int* px1;
int* px2 = &ix;
}

I've moved the expression "int i = 10;" out of the unsafe block and now it compiles. I've also put the code in question in a new project of another instance of vs2012pro. And that also compiles. So now I'm unable to replicate the error.
Here is the code:
int ix = 10;
unsafe
{
int* px1;
int* px2 = &ix;
Test.F(out px1, ref px2);
Console.WriteLine("*px1 = {0}, *px2 = {1}",
*px1, *px2); // undefined behavior
}
Here is the other project:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace saxerium
{
class Program
{
static void Main(string[] args)
{
int ix = 10;
unsafe
{
int* px1;
int* px2 = &ix;
Test.F(out px1, ref px2);
Console.WriteLine("*px1 = {0}, *px2 = {1}",
*px1, *px2); // undefined behavior
}
}
}
class Test
{
static int value = 20;
public unsafe static void F(out int* pi1, ref int* pi2)
{
int i = 10;
pi1 = &i;
fixed (int* pj = &value)
{
// ...
pi2 = pj;
}
}
}
}

Port Selection and Batch Runner Application

I have never written an application, so I will post the entirety of the code (80 lines). (I come from a background of putting together scripts.)
My goal is to load, or create a list of "used" ports, choose a number within a range that isn't on the list, and if the amount of tries to reach an unused port reaches 129, to run a windows batch file.
This also would turn the chosen port into a .cmd
(some of this is an amalgamation of sources from SO)
using System;
using System.Collections.Generic;
using System.Text;
using System.Linq;
using System.Diagnostics;
using System.IO;
namespace randomport
{
class Core
{
public const int
minval = 8001,
maxval = 8128;
public static int[] usedPorts = new int[]{};
public static int
chosenPort = 0,
tries = 0,
timeout = 10;
public static bool read = false;
public static void Main()
{
if(!read)
{
Read();
read = true;
}
RandGen();
}
public static void RandGen()
{
Process proc = null;
Random rand = new Random();
if(tries < 129) chosenPort = rand.Next(minval, maxval);
else
{
proc.StartInfo.FileName = #"C:\Users\Administrator\Desktop\TerrariaServer\filebin\sendservfull.bat";
proc.StartInfo.RedirectStandardError = true;
proc.StartInfo.RedirectStandardOutput = true;
proc.StartInfo.UseShellExecute = false;
proc.Start();
proc.WaitForExit
(
(timeout <= 0)
? int.MaxValue : timeout * 100 * 60
);
}
for(int i = 0; i < usedPorts.Length; i++)
{
if(chosenPort != usedPorts[i])
{
Write();
// Application.Exit();
}
else
{
tries += 1;
return;
}
}
}
public static void Read()
{
using (StreamReader sr = new StreamReader(#"C:\Users\Administrator\Desktop\TerrariaServer\filebin\activeports.txt"))
{
string[] values = sr.ReadToEnd().Split(';');
for(int i = 0; i < values.Length; i++)
{
int.TryParse(values[i], out usedPorts[i]);
}
}
}
public static void Write()
{
File.AppendAllText(#"C:\Users\Administrator\Desktop\TerrariaServer\filebin\activeports.txt", "set port="+chosenPort+";");
File.Move(#"C:\Users\Administrator\Desktop\TerrariaServer\filebin\activeports.txt", Path.ChangeExtension(#"C:\Users\Administrator\Desktop\TerrariaServer\filebin\activeports.txt", ".cmd"));
}
}
}
I have a little work to do on the final export (like removing ";").
The script compiles, but does not run as intended. Something is definitely wrong, but I am unaware of it. If it is something obvious, I guess that would be handy, otherwise if it is simply format and so on, I clearly need to do a little more studying.

Compiled using visual studio 2008 express this time, and cleaned it up. It was hard to tell which were the issues without a debugger, such as a missing parenthesis.
File writing, compiling, and crashing solved..
using System;
using System.Collections.Generic;
using System.Text;
using System.Linq;
using System.Diagnostics;
using System.IO;
namespace randomport
{
class Core
{
public static int[] usedPorts = new int[] { };
public static int
minval = 8001,
maxval = 8129,
chosenPort = 0,
timeout = 10,
temp = 1024;
public static bool read = false;
public static void Main(string[] args)
{
string path = System.Environment.GetEnvironmentVariable("USERPROFILE");
if (!Directory.Exists(String.Concat(path, "\\desktop\\TerrariaServer\\filebin\\activeports.txt")))
{
Directory.CreateDirectory(String.Concat(path, "\\desktop\\TerrariaServer\\filebin"));
// using (StreamWriter sw = File.CreateText(String.Concat(path, "\\desktop\\TerrariaServer\\filebin\\activeports.txt"))) { }
}
if (!Directory.Exists(String.Concat(path, "\\desktop\\TerrariaServer\\filebin\\chosenport.cmd")))
{
Directory.CreateDirectory(String.Concat(path, "\\desktop\\TerrariaServer\\filebin"));
using (StreamWriter sw = File.CreateText(String.Concat(path, "\\desktop\\TerrariaServer\\filebin\\chosenport.cmd"))) { }
}
if (args.Length > 0)
{
if (args[0] == "-noread")
{
}
else if (args[0] == "-read" || args[0] == "-default")
{
if (!read)
{
Read();
read = true;
}
}
}
else
{
if (!read)
{
Read();
read = true;
}
}
if (args.Length >= 3)
{
if (args[1] != "-default" || args[1] != "0")
{
int.TryParse(args[1], out temp);
if (temp > 1024 && temp < 65535)
{
minval = temp;
}
}
if (args[2] != "-default" || args[2] != "0")
{
int.TryParse(args[2], out temp);
if (temp > 1024 && temp < 65535)
{
maxval = temp;
}
}
}
RandGen();
}
public static void RandGen()
{
string path = System.Environment.GetEnvironmentVariable("USERPROFILE");
Random rand = new Random();
chosenPort = rand.Next(minval, maxval);
for (int i = 0; i < usedPorts.Length; i++)
{
if (chosenPort != usedPorts[i])
{
Write();
}
else return;
}
}
public static void Read()
{
string path = System.Environment.GetEnvironmentVariable("USERPROFILE");
if (!File.Exists(String.Concat(path, "\\desktop\\TerrariaServer\\filebin\\activeports.txt")))
{
File.Create(String.Concat(path, "\\desktop\\TerrariaServer\\filebin\\activeports.txt"));
}
using (StreamReader sr = new StreamReader(String.Concat(path, "\\desktop\\TerrariaServer\\filebin\\activeports.txt")))
{
string[] values = sr.ReadToEnd().Split(';');
usedPorts = new int[values.Length];//Initialize the array with the same length as values
for (int i = 0; i < values.Length; i++)
{
int.TryParse(values[i], out usedPorts[i]);
}
}
}
public static void Write()
{
string path = System.Environment.GetEnvironmentVariable("USERPROFILE");
File.AppendAllLines(String.Concat(path, "\\desktop\\TerrariaServer\\filebin\\activeports.txt"), new string[] { chosenPort + ";" });
using (StreamWriter sw2 = File.CreateText(String.Concat(path, "\\desktop\\TerrariaServer\\filebin\\chosenport.cmd")))
{
sw2.WriteLine("set port=" + chosenPort);
}
Environment.Exit(0);
}
}
}