Develop Reference

Why Input string was not in a correct format and exception was unhandled

I am getting an error while taking array input from the user.
static void Main(string[] args)
{
int[] arrSum = new int[] { };
Console.WriteLine("Enter the array Size:\t");
int n = Convert.ToInt32(Console.ReadLine());
Console.WriteLine("Enter the array elements of {0} as Array Size:\n",n);
for (int i = 0; i < n; i++)
{
arrSum[i] = int.TryParse(Console.ReadLine(), out arrSum[]);
}
Console.WriteLine("Enter the number whose sum you want to find:\n");
int j = Convert.ToInt32(Console.ReadLine());
ArraySum(arrSum,n,j);
}
public static int ArraySum(int[] arr, int key, int n)
{
for (int i = 0; i < arr.Length; i++)
{
int first = arr[i];
for (int k = i+1; k < arr.Length; k++)
{
int second = arr[k];
while (first + second == key)
{
Console.WriteLine("The numbers whose sum is {0}" + key + "are:\n" + first + second);
}
if (first + second != key)
{
return -1;
}
else
{
return 1;
}
}
}
return 0;
}
To take array size and elements and the number whose sum we need to compare among the given array elements from the user as input and return the possible pairs whose sum is equal to the given number.

I am not sure if I met the same problem as you, but I modified your code as following. At first I created a safe console readline method for integer that there is no exception thrown if an invalid integer is entered:
private static int GetIntFromInput()
{
while (true)
{
string value = Console.ReadLine();
if (!int.TryParse(value, out int parsedInt))
{
Console.WriteLine("Invalid integer! Retry or Ctrl+C to abort program...");
continue;
}
return parsedInt;
}
}
Then I modified your first method as following:
static void Main(string[] args)
{
Console.WriteLine("Enter the array Size:\t");
int n = GetIntFromInput();
if (n <= 0)
{
Console.WriteLine("Array has to be at least of size 1...");
return;
}
Console.WriteLine("Enter the array elements of {0} as Array Size:\n", n);
var arrSum = new int[n];
for (int i = 0; i < n; i++)
{
int newInt = GetIntFromInput();
arrSum[i] = newInt;
}
Console.WriteLine("Enter the number whose sum you want to find:\n");
int j = Convert.ToInt32(Console.ReadLine());
ArraySum(arrSum, n, j);
}
With this my tests had been successful. Please note, that I did not replace the last Convert.ToInt32 for j.
As a note, please always verify user input as far as possible for not throwing exceptions. If anytime you will check anything not correctly it will crash sometime for sure...
have a great day!

I just have modified your array input code lines, pretty much straight forward. You can use int.TryParse as well just in case you wish to have a check
Console.WriteLine("Enter the array Size:\t");
int n = Convert.ToInt32(Console.ReadLine());
int[] arrSum = new int[n];
Console.WriteLine("Enter the array elements of {0} as Array Size:\n",n);
for(int i = 0;i<n;i++){
arrSum[i]= Convert.ToInt32(Console.ReadLine());
}
Console.WriteLine("Enter the number whose sum you want to find:\n");
int j = Convert.ToInt32(Console.ReadLine());
ArraySum(arrSum,n,j);

c# subtract a number from an array index in a for loop

I need to find the difference of each number value in an array from an average value. I need to loop through each value and subtract each value FROM the average and display the difference. I have tried several different ways but the difference always comes out as 0 at the end. What am i doing wrong here?
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using static System.Console;
namespace AvgNDiff
{
class Program
{
static void Main(string[] args)
{
int[] numbers = new int[10];
int x = 0;
int i;
string entryString = "";
int counter = 0;
int countdown = 10;
int sum = 0;
int average = 0;
while (counter < numbers.Length && numbers[x] != 10 && entryString != "0")
{
if (x == 0)
Write("Enter up to 10 numbers or type 0 to stop > ");
else if (x == 9)
Write("Enter {0} more number or type 0 to stop > ", countdown);
else
Write("Enter up to {0} more numbers or type 0 to stop > ", countdown);
entryString = ReadLine();
numbers[x] = Convert.ToInt32(entryString);
if (entryString != "0")
{
sum += numbers[x];
counter++;
x++;
}
countdown--;
}
average = sum / x;
WriteLine("\n\nYou entered {0} numbers with a sum of {1}", x, sum);
WriteLine("The average of your numbers is " + average);
WriteLine("\n\nNumber Difference");
WriteLine("-------------------------------");
for (i=0; i < x; i++)
{
int value = numbers[i];
int diff = average-value;
WriteLine(String.Format("{0,-10} {1,-10}", (numbers[i]), diff));
}
ReadKey();
}
}
}

Take a look here
int value = numbers[i];
int diff = value - average;
WriteLine(String.Format("{0,-10} {1,-10}", (numbers[i]), value));
the key issue here is the writeline statement.
Youve told it to display numbers[i], and oh wait.. numbers[i] (as thats what value is)
yet diff contains the variance from the average...

static void Main(string[] args)
{
List<int> numberList = new List<int>();
Console.WriteLine("Enter up to 10 numbers or type 0 to stop:");
for (int i = 0; i < 10; i++)
{
int userInput = 0;
while (!int.TryParse(Console.ReadLine(), out userInput))
{
Console.WriteLine("Only integer numbers accepted, let's try again...:");
}
if (userInput == 0)
{
break;
}
else
{
numberList.Add(userInput);
if (i < 9)
{
Console.WriteLine("Yeah, {0} more number{1} to go!", (9 - i), (i == 8 ? "" : "s"));
}
}
}
double average = numberList.Average();
for (int i = 0; i < numberList.Count; i++)
{
Console.WriteLine("#{0}: {1} - {2} = {3}", (i+1), numberList[i], average, (numberList[i] - average));
}
Console.ReadLine();
}

Do not cram the entire soultion into the single Main, extract (and debug) a method:
// Subtract each item from the average
private static double[] MyNormalize(int[] source) {
double sum = 0.0;
foreach (var item in source)
sum += item;
double[] result = new double[source.Length];
for (int i = 0; i < source.Length; ++i)
result[i] = sum / source.Length - source[i];
return result;
}
...
static void Main(string[] args) {
int[] numbers = new int[10];
...
// Input
while (counter < numbers.Length && numbers[x] != 10 && entryString != "0") {
...
entryString = ReadLine();
numbers[x] = Convert.ToInt32(entryString);
}
// Business logic
double[] norm = MyNormalize(numbers);
// Output
for (int i = 0; i < numbers.Length; ++i)
WriteLine(String.Format("{0,-10} {1,-10}", numbers[i], norm[i]));
}

Getting an error about variable not existing in current context

I have written out a program that declares an array of 10 integers, takes input from the user and puts them in the array and then accepts out parameters for the highest value, lowest value, sum of all values, and the average.
The main method displays all the stats. I don't know why, but I get the error
k does not exist in the current context - line 51 column 5
when I have previously declared it before that given line. Any help would be appreciated.
using System;
namespace IntegerStatistics
{
class Program
{
static void Main()
{
Console.Clear();
// Declaring variables
int[] userArray = FillArray();
int ArrayHighest = 0;
int ArrayLowest = 0;
int ArraySum = 0;
int ArrayAverage = 0;
Calculations(userArray, out ArrayHighest, out ArrayLowest, out ArraySum, out ArrayAverage);
Console.WriteLine("The lowest value in the array is {0}, while the highest is {1}.", ArrayLowest, ArrayHighest);
Console.WriteLine("The array has a sum of {0} and averages out to {1}.", ArraySum, ArrayAverage);
Console.ReadLine();
}
private static int[] FillArray()
{
int[] intArray = new int[10];
int numbersEntered = 0;
int intTemp = 0;
string strTemp = "";
for(int k = 0; k < 10; ++k)
{
Console.WriteLine("Enter a whole number or 999 to quit: ");
strTemp = Console.ReadLine();
while(!int.TryParse(strTemp, out intTemp))
{
Console.WriteLine("Input was not in the correct format");
Console.Write("Please enter a valid number: ");
strTemp = Console.ReadLine();
}
}
if(intTemp != 999)
{
intArray[k] = intTemp;
++numbersEntered;
}
else
{
k = 10;
}
Array.Resize(ref intArray, numbersEntered);
return intArray;
}
private static void Calculations(int[] intArray, out int Highest, out int Lowest, out int intSum, out int average)
{
intSum = 0;
Array.Sort(intArray);
Lowest = intArray[0];
Array.Reverse(intArray);
Highest = intArray[0];
Array.Reverse(intArray);
for(int k = 0; k < intArray.Length; ++k)
{
intSum += intArray[k];
}
average = intSum / intArray.Length;
}
}
}
The line I'm specifically having issues with is:
if (intTemp != 999)
{
intArray[k] = intTemp;
++numbersEntered;
}
else
{
k = 10;
}

I think you meant to place the if-else block inside the for-loop.
Since you want to check if the input number is 999 for each iteration, you could write your for-loop like this:
for(int k = 0; k < 10; ++k)
{
Console.WriteLine("Enter a whole number or 999 to quit: ");
strTemp = Console.ReadLine();
while(!int.TryParse(strTemp, out intTemp))
{
Console.WriteLine("Input was not in the correct format");
Console.Write("Please enter a valid number: ");
strTemp = Console.ReadLine();
}
if(intTemp != 999)
{
intArray[k] = intTemp;
++numbersEntered;
}
else
{
k = 10;
}
}

The loop variable k goes out of scope when the code leaves the for loop. So, you can use variable k only within the loop.
So, you need to move your if-else inside your for loop. Change your FillArray() method to
private static int[] FillArray()
{
int[] intArray = new int[10];
int numbersEntered = 0;
int intTemp = 0;
string strTemp = "";
for (int k = 0; k < 10; ++k)
{
Console.WriteLine("Enter a whole number or 999 to quit: ");
strTemp = Console.ReadLine();
while (!int.TryParse(strTemp, out intTemp))
{
Console.WriteLine("Input was not in the correct format");
Console.Write("Please enter a valid number: ");
strTemp = Console.ReadLine();
}
if (intTemp != 999)
{
intArray[k] = intTemp;
++numbersEntered;
}
else
break;
}
Array.Resize(ref intArray, numbersEntered);
return intArray;
}
Also, I'd suggest changing ArrayAverage to double type. e.g. 2, 3 => average 2.5
double ArrayAverage = 0; //average need not be whole number
Additionally, with Linq you can shorten your Calculations method as
//using System.Linq;
private static void Calculations(int[] intArray, out int Highest, out int Lowest, out int intSum, out double average)
{
Lowest = intArray.Min();
Highest = intArray.Max();
intSum = intArray.Sum();
average = intArray.Average();
}

storing the result of a for loop into array and revrse it?

I want to store the result of the for loop in an array then reverse it.
Example:
When I run the program and enter 5 the answer will be
54321
I want it to be
12345
int num;
int index = 0;
Console.Write("Number: ");
num = int.Parse(Console.ReadLine());
for (int x = num; x > 0; x--)
{
index = Convert.ToInt32(index + x);
Console.Write(x);
}
Console.WriteLine("\nThe sum is: {0}", index);
Console.ReadLine();

How about this?
Console.Write("Number: ");
var num = int.Parse(Console.ReadLine()); // parse console input
var range = Enumerable.Range(1, num); //generate array of values from 1 to num
var str = String.Concat(range.Select(x => x.ToString())); //concatenate array of values
Console.WriteLine(str); // write string
var sum = range.Sum(); // get sum of array
Console.WriteLine("\nThe sum is: {0}", sum); // write sum
Console.ReadLine(); // pause

Ok, none of those responses really would do what you asked for, but I mut say your example is really misleading.
Try this:
public int[] ArrayAndReverse(int Number)
{
int[] data = new int[Number];
int index =
for (int x = Number; x > 0; x--)
{
index = Convert.ToInt32(index + x);
Console.Write(x);
}
return data.Reverse().ToArray();
}
now in your console code you can do:
Console.Write("Number: ");
num = int.Parse(Console.ReadLine());
int[] data = ArrayAndReverse(number);
foreach(int i in data)
Console.Write(i);
Also, not sure why your loop is already reversed, I suppose as I said this example is really misleading, else you can just use:
int[] data = Enum.Range(1, number).ToArray();
This will give you already the array in the right order.

Try this
For auto increment to total length
Use this
Console.WriteLine("Input length");
int length;
if (!int.TryParse(Console.ReadLine(), out length))
{
Console.WriteLine("Invalid number");
}
else
{
int[] array = new int[length];
for (int i = length; i > 0; i--)
{
array[length - i] = i;
}
Console.WriteLine("Array is");
foreach (var i in array)
{
Console.WriteLine(i);
}
Console.WriteLine("Reverse Array is");
foreach (var i in array.Reverse())
{
Console.WriteLine(i);
}
}
Console.ReadKey();
To take every number from user, try this
private static void Main(string[] args)
{
Console.WriteLine("Input length");
int length;
if (!int.TryParse(Console.ReadLine(), out length))
{
Console.WriteLine("Invalid number");
}
else
{
int[] array = new int[length];
for (int i = length; i > 0; i--)
{
int input;
Console.WriteLine("Input number");
if (!int.TryParse(Console.ReadLine(), out input))
{
Console.WriteLine("Invalid number");
input = 0;
}
array[length - i] = input;
}
Console.WriteLine("Array is");
foreach (var i in array)
{
Console.WriteLine(i);
}
Console.WriteLine("Reverse Array is");
foreach (var i in array.Reverse())
{
Console.WriteLine(i);
}
}
Console.ReadKey();
}

C# mastermind game

In the Main method, in the for loop, if you copy/paste/run whole program in visual, you'll see that i'm trying to end the game. First "if", if the user hasn't guessed; then attempts decrements by one and keeps guessing. The second "else if", if the user has guessed the PCArray, than the game ends and message shows. those work.
But, the first "else if", if the user has exhausted his attempts to guess, and hasn't guessed PCArray, than it should say "oh no, you couldn't guess..." Why is this not working.
I just want it to work so that if:
- user hasn't guessed but still has attempts, attempts decrements by 1 until 0.
- user has guessed the correct number, it says congrats.
- attempts are 0 and user still hasn't guessed number, then show "oh no..." message.
class Program
{
static void Main(string[] args)
{
string name;
Console.WriteLine("**************Let's play Master-Mined**************");
Console.WriteLine();
Console.Write("Please enter your name: ");
name = Console.ReadLine();
Console.WriteLine("Welcome {0}. Have fun!! ", name);
int numberCount = 0;
int difficultyLevel = 0;
int digitNumber = GetRandomNumberCount(numberCount);
Console.Write(digitNumber + " it is. Let's play.");
Console.WriteLine();
int[] PCArray = GenerateRandomNumbers(digitNumber);
Console.WriteLine("A " + digitNumber + "-digit number has been chosen. Each possible digit may be the number 1, 2, 3 or 4.");
Console.WriteLine(" ******");
int difficulty = GetGameDifficulty(difficultyLevel);
int attempts = difficulty * digitNumber;
Console.WriteLine("Enter your guess ({0} guesses remaining)", attempts);
int remaining = attempts;
for (int i = 0; i < attempts; i++)
{
int[] userArray = GetUserGuess(digitNumber);
int hits = CountHits(PCArray, userArray, attempts);
if ((hits != PCArray.Length) && (attempts > 0))
{
remaining--;
Console.WriteLine("Enter your guess ({0} guesses remaining)", remaining);
}
else if ((attempts < 1))
{
Console.WriteLine("Oh no {0}! You couldn't guess the right number.", name);
Console.WriteLine("The correct number is: ");
for (int j = 0; j < PCArray.Length; j++)
{
Console.Write(PCArray[j] + " ");
}
Console.WriteLine("Would you like to play again (Y/N)? ");
}
else if (hits == PCArray.Length)
{
attempts = 0;
Console.WriteLine("You win {0}!", name);
Console.WriteLine("The correct number is:");
for (int j = 0; j < PCArray.Length; j++)
{
Console.Write(PCArray[j] + " ");
}
}
}
Console.ReadLine();
}
public static int GetRandomNumberCount(int numberCount)
{
int number = 0;
do
{
try
{
Console.Write("How many numbers would you like to use in playing the game (4-10)? ");
number = int.Parse(Console.ReadLine());
Console.WriteLine();
}
catch
{
Console.WriteLine("You must pick a number between 4 and 10. Choose again.");
Console.WriteLine();
}
} while ((number < 4) || (number > 10));
return number;
}
public static int GetGameDifficulty(int difficultyLevel)
{
int difficulty = 0;
do
{
try
{
Console.Write("Choose a difficulty level (1=hard, 2=medium, 3=easy): ");
difficulty = int.Parse(Console.ReadLine());
}
catch
{
Console.WriteLine(" Incorrect entry: Please re-enter.");
}
} while ((difficulty < 1) || (difficulty > 3));
return difficulty;
}
public static int[] GenerateRandomNumbers(int PCSize)
{
int eachNumber;
int[] randomNumber = new int[PCSize];
Random rnd = new Random();
for (int i = 0; i < randomNumber.Length; i++)
{
eachNumber = rnd.Next(1, 5);
randomNumber[i] = eachNumber;
Console.Write(eachNumber);
}
Console.WriteLine();
return randomNumber;
}
public static int[] GetUserGuess(int userSize)
{
int number = 0;
int[] userGuess = new int[userSize];
for (int i = 0; i < userGuess.Length; i++)
{
Console.Write("Digit {0}: ", (i + 1));
number = int.Parse(Console.ReadLine());
userGuess[i] = number;
//Console.Write(number);
}
Console.WriteLine();
Console.Write("Your guess: ");
for (int i = 0; i < userGuess.Length; i++)
{
Console.Write(userGuess[i] + " ");
}
Console.WriteLine();
return userGuess;
}
public static int CountHits(int[] PCArray, int[] userArray, int attempts)
{
int hit = 0;
int miss = 0;
int hits = 0;
for (int i = 0; i < PCArray.Length; i++)
{
if (PCArray[i] == userArray[i])
{
hit = hit + 1;
hits = hit;
}
else
{
miss = miss + 1;
}
}
Console.WriteLine("Results: {0} Hit(s), {1} Miss(es)", hit, miss);
return hits;
}
}

First of all, you should rethink your code, because the flow control is scattered throughout your code. For example, you don't need both attempts and remaining, they control the same thing.
Using two variables to control the same thing is what is causing your problem. The first two ifs in your for should be like this:
if (hits != PCArray.Length && remaining > 1)
and
else if (remaining == 1)
Note I removed the unnecessary parenthesis. With these changes, your application works, although the code is not too pretty.
A simple way of enhancing your code is to first check for the right result, and if it's not, then decrease the attempts variable and finally check for its value. That's why with your code as it is, the if should compare to 1 instead of 0.
The hits variable in your CountHits method is totally unnecessary; you should just return hit. Actually the miss variable can be avoided too, you can calculate it. Also remember to use the ++ operator.
But as I said first, the important thing is not to make it work but to organize your code properly. Later I will post my version.
My version, it's not the most beautiful thing in the world but I didn't want to change much of your code structure:
class Program
{
static void Main(string[] args)
{
Console.WriteLine("************** Let's play Master-Mind **************\n");
string name = GetPlayerName();
do
{
Play(name);
Console.Write("\nWould you like to play again (Y/N)? ");
}
while (Console.ReadLine().ToUpper() == "Y");
}
private static void Play(string name)
{
int numberCount = GetRandomNumberCount();
Console.Write(numberCount + " it is. Let's play.");
Console.WriteLine();
int[] PCArray = GenerateRandomNumbers(numberCount);
Console.WriteLine("A {0}-digit number has been chosen. Each possible digit may be the number 1 to 4.\n", numberCount);
int difficulty = GetGameDifficulty();
bool won = false;
for (int allowedAttempts = difficulty * numberCount; allowedAttempts > 0 && !won; allowedAttempts--)
{
Console.WriteLine("\nEnter your guess ({0} guesses remaining)", allowedAttempts);
int[] userArray = GetUserGuess(numberCount);
if (CountHits(PCArray, userArray) == numberCount)
won = true;
}
if (won)
Console.WriteLine("You win, {0}!", name);
else
Console.WriteLine("Oh no, {0}! You couldn't guess the right number.", name);
Console.Write("The correct number is: ");
for (int j = 0; j < numberCount; j++)
Console.Write(PCArray[j] + " ");
Console.WriteLine();
}
private static string GetPlayerName()
{
Console.Write("Please enter your name: ");
string name = Console.ReadLine();
Console.WriteLine("Welcome, {0}. Have fun!!\n", name);
return name;
}
public static int GetRandomNumberCount()
{
int number;
Console.Write("How many numbers would you like to use in playing the game (4-10)? ");
while (!int.TryParse(Console.ReadLine(), out number) || number < 4 || number > 10)
Console.WriteLine("You must pick a number between 4 and 10. Choose again.");
return number;
}
public static int GetGameDifficulty()
{
int difficulty = 0;
Console.Write("Choose a difficulty level (1=hard, 2=medium, 3=easy): ");
while (!int.TryParse(Console.ReadLine(), out difficulty) || difficulty < 1 || difficulty > 3)
Console.WriteLine("Incorrect entry: Please re-enter.");
return difficulty;
}
public static int[] GenerateRandomNumbers(int PCSize)
{
int eachNumber;
int[] randomNumber = new int[PCSize];
Random rnd = new Random();
Console.Write("PC number: ");
for (int i = 0; i < PCSize; i++)
{
eachNumber = rnd.Next(1, 5);
randomNumber[i] = eachNumber;
Console.Write(eachNumber);
}
Console.WriteLine();
return randomNumber;
}
public static int[] GetUserGuess(int userSize)
{
int number = 0;
int[] userGuess = new int[userSize];
for (int i = 0; i < userSize; i++)
{
Console.Write("Digit {0}: ", (i + 1));
while (!int.TryParse(Console.ReadLine(), out number) || number < 1 || number > 4)
Console.WriteLine("Invalid number!");
userGuess[i] = number;
}
Console.WriteLine();
Console.Write("Your guess: ");
for (int i = 0; i < userSize; i++)
{
Console.Write(userGuess[i] + " ");
}
Console.WriteLine();
return userGuess;
}
public static int CountHits(int[] PCArray, int[] userArray)
{
int hits = 0;
for (int i = 0; i < PCArray.Length; i++)
{
if (PCArray[i] == userArray[i])
hits++;
}
Console.WriteLine("Results: {0} Hit(s), {1} Miss(es)", hits, PCArray.Length - hits);
return hits;
}
}
It does a few more validations and it even actually lets you play again! ;)