So I am currently pretty confused (keep in mind im new to coding).
I am currently trying to create a program which creates allows the user to input the amount of numbers they would like to enter in the array (it then creates an array based on that length), asks the user to input the numbers into their desired position.
My code currently looks like this:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace Arrays
{
class Program
{
static void Main(string[] args)
{
//Variables
int[] array1 = new int[0];
int TotalArray, position, Number;
//Main Program
Console.WriteLine("Hello, welcome to creating your own array!");
Console.WriteLine("How many numbers do you wish to add to the array?: ");
TotalArray = int.Parse(Console.ReadLine());
Console.ReadKey();
{
Console.WriteLine("What position would you like to add your number to?: ");
position = int.Parse(Console.ReadLine());
if (position < TotalArray)
{
Console.WriteLine("What number would you like to add to position " + position);
Number = int.Parse(Console.ReadLine());
array1[position] = Number;
Console.WriteLine("Testing: " + array1[position]);
Console.ReadKey();
}
else
{
Console.WriteLine("Error! You entered your position higher than your total array!");
}
}
}
}
}
However, I do not understand how to create an array length based on the users input.
I have to tried to do this:
Console.WriteLine("Hello, welcome to creating your own array!");
Console.WriteLine("How many numbers do you wish to add to the array?: ");
TotalArray = int.Parse(Console.ReadLine());
int i = Convert.ToInt32(TotalArray);
int[] array1 = new int[i];
But get this error:
A local variable or function named 'array1' is already defined in this scope
I don't really understand what this piece of code does:
int i = Convert.ToInt32(TotalArray);
int[] array1 = new int[i];
However, I saw it mentioned on stackoverflow and thought id try an implement it. I kinda understand the 2nd line but don't really get the whole converting thing.
Any help would greatly be appreciated!
First, you don't need to convert TotalArray to an integer, since you already parsed the user's repsonse as an integer. So omit i. Next, you're declaring a new array1. Instead, just assign a new one to the same reference:
array1 = new int[TotalArray];
As for the loop. Here's the naive version, but if you need to scold the user for picking the same position twice, you'll need to do a lot more work.
int requestCount = TotalArray;
while (requestCount > 0)
{
requestCount = requestCount - 1;
Console.WriteLine("What position would you like to add your number to? (0 - "
+ (TotalArray - 1) + "): ");
position = int.Parse(Console.ReadLine());
if (position < TotalArray)
{
Console.WriteLine("What number would you like to add to position " + position);
Number = int.Parse(Console.ReadLine());
array1[position] = Number;
Console.WriteLine("Testing: " + array1[position]);
Console.ReadKey();
}
else
{
Console.WriteLine("Error! You entered your position higher than your total array!");
}
}
first this is the right way to write your code
Console.WriteLine("Hello, welcome to creating your own array!");
Console.WriteLine("How many numbers do you wish to add to the array?: ");
TotalArray = int.Parse(Console.ReadLine());
array1 = new int[TotalArray];
the third line means read the last line entered into the console then convert it to a value of type int, then store this value in the variable TotalArray
while the fourth line means construct a new array of length TotalArray then store the resulted array into the variable array1
this doesn't work when you write int[] array1 = new int[i]; because it means create a new variable called array1 then create a new array of length i to be stored in the newly created variable array1
and as you can see in your code you've already defined array1
here:
//Variables
int[] array1 = new int[0];
this is why you get the message: A local variable or function named 'array1' is already defined in this scope
but good job for a beginner.
Related
I'm getting different user input instead of getting real inputs given by user in codechef
User Input:
4
1 2 3 4
Expected Output:
4 3 2 1
using System;
public class Test
{
public static void Main()
{
int N = Convert.ToInt32(Console.ReadLine());
int[] arr = new int[N];
for(int i=0;i<N;i++){
arr[i] = Convert.ToInt32(Console.Read());
}
for(int j=N-1;j>=0;j--){
Console.Write(arr[j]);
Console.Write(" ");
}
}
}
Output I got:
32 50 32 49
Since you said you want to do it without ReadLine, let's work with your current code. There are two issues at hand.
You should skip the spaces
You get the character codes instead of the values
To skip the spaces, you can simply read them and do nothing with the read character. I implemented this below in a way that assumes after every number (one digit long) there will be a single space to ignore. But you could also do that in a less hacky way by checking what the read character actually is before you discard it.
To get the character code into the value, I first perform a conversion into a char by casting it. Then I get the numeric value, which might be a double. But because you know that your numbers are integers, we can cast that to int.
using System;
class Program {
static void Main(string[] args) {
int N = Convert.ToInt32(Console.ReadLine());
int[] arr = new int[N];
for(int i=0;i<N;i++){
arr[i] = (int)Char.GetNumericValue((char)Console.Read());
Console.Read();
}
for(int j=N-1;j>=0;j--){
Console.Write(arr[j]);
Console.Write(" ");
}
}
}
For some reason, I continue to get a system format exception at the int32.parse line. I don’t understand what I’m doing wrong.
My assignment is to:
Create a simple application in which you have variables of appropriate types to
store the user’s name and three test grades.
Ask for this information from the user and store it appropriately.
Create a variable to store the user’s test average.
Calculate and assign
this value using the stored information given to you by the user.
My code follows:
class MainClass
{
public static void Main (string[] args)
{
Console.WriteLine ("Please enter your name: ");
string name;
name = Console.ReadLine ();
Console.WriteLine ("Hello, " + name);
int score;
Console.Write ("What are your last three test scores: ");
score = Int32.Parse(Console.ReadLine ());
Console.WriteLine("Your test scores are" + score + "90,92,95");}
}
It's important to inspect user input in order to avoid Exceptions due to invalid input. Here's how I would do it:
class MainClass
{
public static void Main(string[] args)
{
//Variable Declarations
string response,
name;
string[] scores;
int sumOfAllScores,
scoreCount;
bool validResponse;
System.Text.RegularExpressions.Regex onlyDigits;
//We need to assign response an initial value or else Visual Studio will complain
//since it only receives its real value within a while loop (which as far as the parser is concerned
//may or may not ever iterate.
response = string.Empty;
//Booleans are automatically assigned an intial value of 'false' but I like to intialize them anyway
validResponse = false;
//Initialize the score sum and score counter variables.
sumOfAllScores = 0;
scoreCount = 0;
//This Regex pattern will allow us to inspect a string to ensure that it contains only digits.
onlyDigits = new System.Text.RegularExpressions.Regex(#"^\d+$");
Console.Write("Please enter your name: ");
name = Console.ReadLine();
Console.WriteLine("Hello, " + name);
//This loop will iterate until the user provides valid input (comma-separated integers).
while (!validResponse)
{
//When we enter the while loop, set validResponse to true.
//If we encounter any invalid input from the user we will set this to false so that
//the while loop will iterate again.
validResponse = true;
Console.Write("What are your last three test scores (comma-separated list, please): ");
response = Console.ReadLine();
//Split response into an array of strings on the comma characters
scores = response.Split(',');
//Inspect each element of the string array scores and take action:
foreach (string scoreEntry in scores)
{
//If the current array member being inspected consists of any characters that are not integers,
//Complain to the user and break out of the foreach loop. This will cause the while loop to iterate
//again since validResponse is still false.
if (!onlyDigits.IsMatch(scoreEntry))
{
//Complain
Console.WriteLine("Invalid response. Please enter a comma-separated list of test scores");
Console.WriteLine(Environment.NewLine);
//Re-initialize the score sum and score count variables since we're starting over
sumOfAllScores = 0;
scoreCount = 0;
//Set validResponse to false and break out of the foreach loop
validResponse = false;
break;
}
//Otherwise, we have valid input, so we'll update our integer values
else
{
//Iterate the number of scores that have been entered and validated
scoreCount++;
//Use the static Convert class to convert scoreEntry to an Integer
//and add it to the score sum
sumOfAllScores += Convert.ToInt32(scoreEntry);
}
}
}
//Report the results to the user:
Console.WriteLine("Your test scores are: " + response);
Console.WriteLine("Your average score is " + sumOfAllScores / scoreCount);
}
}
Console.Readline() returns a string. In your case this string might be something like "96,92,99".
string inputs = Console.ReadLine();
First step would be to split the string into three strings like "96", "92", "99" by using the comma as a separator
string[] parts = input.Split(',');
Now each string needs to be converted into an integer, one by one
// Create array of integers with the same size as the array of parts
int[] grades = new int[parts.Length];
// Loop through the input parts and convert them into integers
for(i=0; i<parts.Length; i++)
{
// Use `TryParse()` as it wont throw an Exception if the inputs are invalid
int.TryParse(parts[i], out grades[i]);
}
Now you can do things like calculate an average. I prefer the use the built in functions like .Average() or .Sum()
Console.WriteLine("The average grade is " + grades.Average().ToString("F1"));
You can combine an array of values into a comma separated string using the string.Join() function.
Console.WriteLine("I parsed these values: " + string.Join(",", grades));
So for example if the input is invalid you will see a 0 in place of the invalid value. Here is an example console output.
Enter grades separated by commas:
92,A,96,94
I parsed these values: 92,0,96,94
The average grade is 70.5
To convert the array of strings into an array of integers with one statement, use LINQ.
int[] grades = parts.Select((part) => int.Parse(part)).ToArray();
This will though an exception with invalid inputs. Making the above to work with TryParse() is tricker, but doable.
I have an assignment that requires us to use arrays and not lists. I have two problems right now; one being that every time the user makes an input, the length of array playerNumber increases by one so I need it to be indefinite and I also need to send the array back to the main method. The code below works only once and when I try to enter a second input the program crashes.
int x = 0;
string answer = "yes";
string[] playerNumber = new string[] {};
while (answer == "yes")
{
Console.Write("Enter a number : ");
string y = Console.ReadLine();
playerNumber = new string[] { y };
playerNumber[x - 1] = y;
x++;
Console.Write("Enter another number : ");
answer = Console.ReadLine();
Console.WriteLine();
}
It is not clear what your'e trying to do.
To start with, your index is out of bounds.
Your'e doing: playerNumber[x-1], but x == 0, so you get an exception. This is the only reason your code fails. Note that taking the ++x; one line up will also fail you, since in the second loop, playerNumber is again an array of size 1, but x value is now 2, and your'e again out of bounds.
Secondly, your'e initializing your array both outside and inside the while loop. You have no use of the outer initialization (and maybe there's no need for the inner one - again, depends on what exactly you're trying to achieve).
Thirdly, you should give the user the correct instruction: If you want answer to be yes or no, specify it in your Console.Write.
So if I managed to guess what you were trying to do, here's your code with a few changes, including the usage of Array.Resize (which is very inefficient in this context), and returning the array, as you asked:
using System;
public class Test
{
public static string[] MyFunc()
{
int x = 1;
string answer = "yes";
string[] playerNumber = new string[x];
while (answer == "yes")
{
Console.Write("Enter a number : ");
string y = Console.ReadLine();
playerNumber[x-1] = y;
x++;
Array.Resize(ref playerNumber, x);
Console.Write("Would you like to enter another number? (yes/no)");
answer = Console.ReadLine();
Console.WriteLine();
}
return playerNumber;
}
public static void Main()
{
Console.WriteLine(MyFunc()[0]); // prints the first string
}
}
In general, I know that int32 errors mean that a string value is not getting converted for the console program. I have seen a lot of code trying to find the answer to this including the following stackoverflow questions (seen much more but these were most useful:
How to sum up an array of integers in C#
Error CS1501: I'm not overloading a Sum() method correctly
CS0019 Operator cannot be applied to operands of type 'bool' and 'int'
That being said, this is also a homework assignment, titled UsingSum.cs as seen in a couple of these links. The difference in mine and these is that I am trying to make it so that the user enters however many Integers they want, then they are added up. The entire assignment is written in link 2....
The problem: I keep getting either 0 or System.Int32[] instead of the sum, despite the changes I make.
I cannot use Linq.
Here is the code:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace UsingSum
{
class Program
{
static void Main(string[] args)
{
int i;
int usrInput;
bool running = true;
//Enter Question Asking Loop w/ running=true
while (running)
{
Console.Write("Enter a number or enter 999 to exit: ");
int[] array1 = new int[0];
for (i = 0; i < array1.Length; i++)
{
usrInput = Convert.ToInt32(Console.ReadLine());
array1[i] = Convert.ToInt32(usrInput);
}
for (i = 0; i < array1.Length; i++)
{
Console.WriteLine(array1[i]);
}
/*If the user enters 999, calls Sum() and asks user to press any key to exit.
changes 'running' from true to false to exit the question loop*/
int exit = Convert.ToInt32 (Console.ReadLine());
if (exit == 999)
{
running = false;
Sum(array1);
}
}
//Loop complete
Console.WriteLine("Press any key to exit.");
Console.ReadLine();
}
public static void Sum(int[] numbers)
{
int [] sum1 = new int [0];
int sum2 = 0;
//Program accepts user responses with or w/o this loop...Int.32 error present both ways
//for (int a = 0; a < numbers.Length; ++a)
//sum1[a] = a;
//additional loop tried w/o the loop above/below;
//when used in the WriteLine w/ sum2 it displays 0, when used with sum1 or numbers Int.32 error
//Array.ForEach(sum1, delegate(int i) { sum2 += i; });
foreach (int i in numbers)
sum2 =+ i;
Console.WriteLine("The sum of the values in your array is: " + sum1);
/*tried changing 'numbers' to sum1, sum2, sum1.Convert.ToString(),sum2.Convert.ToString()
numbers.Convert.ToString(), also tried converting sum2 to a string.*/
}
}
}
Here is my final solution!
static void Main(string[] args)
{
AskUserForNumbers();
Console.WriteLine("Press any key to exit");
Console.ReadLine();
}
public static List<Int32> AskUserForNumbers()
{
bool running = true;
List<int> numbers = new List<int>();
while (running)
{
Console.Write("Enter a number or enter 999 to exit: ");
int inputValue;
var inputString = Console.ReadLine();
//Check for "999" which indicates we should display the numbers entered, the total and then exit our loop.
if (inputString == "999")
{
Console.WriteLine("The sum of the values in your array is: " + numbers.Sum());
running = false;
}
else if (Int32.TryParse(inputString, out inputValue) && inputValue > 0)
{
numbers.Add(inputValue);
}
else
{
Console.WriteLine("Please enter a whole number greater than 0");
}
}
return numbers;
}
}
}
A few problems:
First, you're always declaring your arrays as int[] array1 = new int[0];. This means that your code for actually getting the user input will never hit. Maybe you should try using a different collection type (List<int> maybe).
Second, you never perform any error checking when parsing the integer. That's bad practice. You should be using int.TryParse(string input, out result) to verify it was a valid number before adding it to the array.
Third, you are looping over the length of the array for inputs, meaning you will loop through however long the array is, and will continue doing so until the last input you have is the exit number (999).
Fourth, the input you get for the exit code is discarded (not added to the array to sum).
Just remember that programming is very procedural. There should be clear (logical) steps from point a to point b. In fact, imagine you are the program and you're asking a friend to give you numbers to sum up for him. Give him whatever information you think might be useful (such as the exit condition). Diagram the steps, and then try to translate that to code.
Edit: The main point is that an array (which has a fixed size) is NOT the tool for the job here. You're not actually filling the array with any data, so that's why the sum never happens. The culprit is here:
int[] array1 = new int[0]; // Instantiate a zero-length array? Can't hold any values
// Will never hit inside the loop here, because i < array1.Length (which is zero) will always be false.
for (i = 0; i < array1.Length; i++)
You need to either increase the size of the array to begin with (and either reuse the indexes or resize the array) or use an non-fixed collection (List, for example). Finally, when you pass array1 to the Sum method, array1 is empty because you declared it as a zero element array. That is why you always get a zero printing out. Like I said before, imagine you are the program, and actually run through all these steps, LINE BY LINE.
For example, you start in the loop. You prepare a miniature notebook to write down all the numbers your friend is telling you with no pages in it. For every page (and realize there are none) in the notebook, you ask your friend for a number. After you've gone through every page, you now go through every page again to read all the values he gave you (keep in mind he couldn't give you any numbers, since the notebook was empty). Then you ask him one more time for a number, and if it's 999 you tell him you're done and give him the sum of all the numbers you wrote down. If he didn't give you 999 as the number, you repeat the cycle.
Do you understand WHY it's not working now?
public static void Sum(int[] numbers)
{
int sum2 = 0;
foreach (int i in numbers)
sum2 =+ i;
Console.WriteLine("The sum of the values in your array is: " + sum2);
}
foreach (int i in numbers)
sum2 =+ i;
should become
foreach (int i in numbers)
sum2 += i;
Your problem is with your first for loop. You never will add items to your array because your
for (i = 0; i < array1.Length; i++)
Since you only add to your array1 array when you enter the loop, it won't ever increment. Since i = 0 and the array1.Length is 0 to start, i will never be less than the length.
Here is what I would suggest you do.
private static void Main(string[] args) {
var running = true;
var numbers = new List<int>();
//Enter Question Asking Loop w/ running=true
while (running) {
Console.Write("Enter a number or enter 999 to exit: ");
int inputValue;
var inputString = Console.ReadLine();
//Check for "999" which indicates we should display the numbers entered, the total and then exit our loop.
if (inputString == "999") {
//Display the numbers entered
foreach (var number in numbers) {
Console.WriteLine(number);
}
Console.WriteLine("The sum of the values in your array is: " + numbers.Sum());
running = false;
}
else if (Int32.TryParse(inputString, out inputValue) && inputValue > 0) {
//We have valid input, append it to our collection
numbers.Add(inputValue);
}
else {
//The user entered invalid data. Let them know.
Console.WriteLine("Please enter a whole number greater than 0");
}
}
//Loop complete
Console.WriteLine("Press any key to exit.");
Console.ReadLine();
}
You have several small mistakes here.
In your Sum method you are no longer using the array sum1, you're summing the values into sum2, but you're printing sum1. Your sum method should be (as described by Wiktor):
public static void Sum(int[] numbers)
{
int sum2 = 0;
foreach (int i in numbers)
sum2 += i;
Console.WriteLine("The sum of the values in your array is: " + sum2);
}
Also note that you used sum2 =+ i rather than sum2 =+ i. What that's saying is "set sum2 to be equal to the positive value of i" rather than, "add i to sum2.
Next, you have some issues in how you gather your input from the user. First off, arrays don't have a mutable size. The size that they have is fixed when they are created, and the array that you create to hold onto the values to sum up from the users is initialized to a size of 0. (int[] array1 = new int[0];) If you want to get a fixed number of values from the user you can put something other than 0 there for the array size, but based on the context it appears that you want the users to be able to add values until they enter 999 at which point you end. Since you don't know the size before hand you'll want to use a List<int> rather than an array, as you can just add items to it and it will magically grow to support the new items.
I would also suggest making a new method to get all of the values from the user, rather than embedding it in your Main method.
public static List<int> AskUserForNumbers()
{
List<int> numbers = new List<int>();
while(...)//todo determine end condition
{
string userInput = Console.ReadLine();
if(...)//todo determine if user is done
{
}
else
{
int nextNumber = ...;//todo parse user input
numbers.Add(nextNumber);
}
}
return numbers;
}
I'm not sure if it's a requirement for you to stop asking for numbers when the user enters 999 or if that's just what you did. if you have a choice, I would suggest using something different such as a blank line, 0, "quit", "exit", etc. 999 is a number that someone might want to sum.
As mentioned by SPFiredrake, it's best to use int.TryParse() to parse user input, that way if they enter a number that's not an int it won't crash, and you can tell the user that it was no good and they need to try again.
I am working on a project, Yes its for school. I'm having a hard time understanding how to pass the user input and store it with a array. The project is to get high and low temps for seven days and store in different arrays then compute the ave high etc. how do I collect the input and store it in a array in a different class? I think I almost have it but not sure where I'm going wrong
I have this so far but get a error:
Cannot implicitly convert type 'int' to 'int[]'
namespace Project_Console_3
{
class Program
{
static void Main(string[] args)
{
WeeklyTemperature Temp = new WeeklyTemperature();
int Count = 0;
while (Count < 7)
{
Console.WriteLine("Enter The High Temperature for Day {0}", Count+1);
Temp.HTemp1 =Console.ReadLine(); // save the number as a string number
Temp.HTemp = Convert.ToInt32(Temp.HTemp1); // change the string number to a integer as HTemp
Console.WriteLine("--------------------------------");//Draws a line
Console.WriteLine("Enter The Low Temperature for Day {0}", Count+1);
Temp.LTemp1 =Console.ReadLine(); // save the number as a string number
Temp.LTemp = Convert.ToInt32(Temp.LTemp1);
Console.WriteLine("--------------------------------");//Draws a line
Count = Count + 1;
Console.Clear();
}
}
}
}
WeeklyTemperature.cs
namespace Project_Console_3
{
class WeeklyTemperature
{
public int[] HTemp = new int[7];
public int[] LTemp = new int[7];
public string HTemp1;
public string LTemp1;
}
}
It looks like all you need to do is change this line:
Temp.HTemp = Convert.ToInt32(Temp.HTemp1);
to
Temp.HTemp[Count] = Convert.ToInt32(Temp.HTemp1)
Your error message tells you that you have a mismatch in the assignment of variables.
in this line:
Temp.HTemp = Convert.ToInt32(Temp.HTemp1);
The return value is of type int but the variable Temp.HTemp is of type int[] which is an array that holds individual integer.
To store values in an array the compiler has to know at which position it has to put the value.
Indexing an array works with the [] operators:
int pos = 0;
Temp.HTemp[pos] = 5;
will store a 5 on the first position.
Since you have a counting variable in your while loop you can use it to index the position where the numbers should be stored, as Jim Ross already showed in his answer.
More on the topic of indexing you can find here, and a tutorial is here