I seem to of hit a bit of a snag in a program I am trying to make for school. I am suppose to make a new class to receive data and get a total to send to a new screen. Well I did the same thing we did in class, but the difference is that that was from a text box and there is no text box for the data I need to move this time, so the way I tried gave me an error. Here is what I got so far:
public StudentSelection()
{
InitializeComponent();
}
public decimal firstCounter;
public decimal secondCounter;
public decimal finalCounter;
struct StudentScores
{
public string StuId;
public decimal TestOne;
public decimal TestTwo;
public decimal Final;
}
StudentScores[] allStudentScores = new StudentScores[10];
// class level array to hold 10 products - read in from a file
private void StudentSelection_Load(object sender, EventArgs e)
{
// read products file into products structure array
try
{
// ALWAYS initialize a structure array before using the array
// before adding, changing, etc.
for (int x = 0; x < 10; x++)
{
allStudentScores[x].StuId = "";
allStudentScores[x].TestOne = 0;
allStudentScores[x].TestTwo = 0;
allStudentScores[x].Final = 0;
}
int arrayIndex = 0; // needed for incrementing index value of the array
// when reading file into array
// now read file into the array after initialization
StreamReader inputFile;
string lineofdata; // used to hold each line of data read in from the file
string[] ProductStringArray = new string[4]; // 6 element string array to hold
// each "field" read from every line in file
inputFile = File.OpenText("StudentScores.txt"); // open for reading
while (!inputFile.EndOfStream) //keep reading until end of file
{
lineofdata = inputFile.ReadLine(); // ReadLine() reads an entire row of data from file
ProductStringArray = lineofdata.Split(','); //each field is separated by ';'
allStudentScores[arrayIndex].StuId = ProductStringArray[0]; // add first element of array to first column of allProducts
allStudentScores[arrayIndex].TestOne = decimal.Parse(ProductStringArray[1]);
firstCounter += allStudentScores[arrayIndex].TestOne;
allStudentScores[arrayIndex].TestTwo = decimal.Parse(ProductStringArray[2]);
secondCounter += allStudentScores[arrayIndex].TestTwo;
allStudentScores[arrayIndex].Final = decimal.Parse(ProductStringArray[3]);
finalCounter += allStudentScores[arrayIndex].Final;
StudentListView.Items.Add(ProductStringArray[0]);
arrayIndex++; // increment so NEXT row is updated with next read
}
//close the file
inputFile.Close();
}
catch (Exception anError)
{
MessageBox.Show(anError.Message);
}
}
private void NextButton_Click(object sender, EventArgs e)
{
decimal firstResult, secondResult, finalResult, stuOne, stuTwo, stuThree;
string stuName;
// call the method in our datatier class
decimal.TryParse(firstCounter, out firstResult);
decimal.TryParse(secondCounter, out secondResult);
decimal.TryParse(finalCounter, out finalResult);
DataTier.AddOurNumbers(firstResult, secondResult, finalResult);
DataTier.StudentData(stuName, stuOne, stuTwo, stuThree);
// now hide this window and display a third window with the total
this.Hide();
// display third window
ScoreScreen aScoreScreen = new ScoreScreen();
aScoreScreen.Show();
}
}
and my new class
class DataTier
{
// public static variable available to all windows
public static decimal firstTotal, secondTotal, finalTotal, stuTestOne, stuTestTwo, stuTestThree;
// static is not associated with any object
public static string stuIDCode;
// create a public method to access from all windows
public static void AddOurNumbers(decimal NumOne, decimal NumTwo, decimal numThree)
{
// devide to get an average
firstTotal = NumOne / 10;
secondTotal = NumTwo / 10;
finalTotal = numThree / 10;
}
public static void StudentData(string name, decimal testOne, decimal testTwo, decimal testThree)
{
stuIDCode = name;
stuTestOne = testOne;
stuTestTwo = testTwo;
stuTestThree = testThree;
}
}
The error is at the three decimal.TryParse parts and I have no clue why it is not working except the error says "cannot convert from decimal to string". Any help will be appreciated.
Change it from:
decimal.TryParse(firstCounter, out firstResult);
decimal.TryParse(secondCounter, out secondResult);
decimal.TryParse(finalCounter, out finalResult);
DataTier.AddOurNumbers(firstResult, secondResult, finalResult);
To:
DataTier.AddOurNumbers(firstCounter, secondCounter, finalCounter);
The problem is that you're trying to call decimal.TryParse(string s, out decimal result) as decimal.TryParse(decimal s, out decimal result).
Your input is already decimal and doesn't require any conversion.
As a side note is that the code
decimal.TryParse(someString, out someOutputDecimal);
without a proper if statement around it will fail silently (it doesn't inform anything about the failure). In fact the output value is set to 0, and it acts as if no faulty input was received. If the input should always be valid, you should use decimal.Parse(someString) instead. However in some cases defaulting to 0 if the input is invalid, can be the desired behavior.
The decimal.TryParse() method takes a string as its first argument and attempts to convert it to a decimal value. In your case, the variables you are passing to TryParse() are already decimal variables and there is no need to parse them. If you want to just copy class variables to local variables, all you need to do is this:
firstResult = firstCounter;
secondResult = secondCounter;
finalResult = finalCounter;
Or in this particular case, you can just pass the class variables directly into AddOurNumbers:
DataTier.AddOurNumbers(firstCounter, secondCounter, finalCounter);
One thing to note here is that value types, such as decimals and other primitives in C# get copied any time you assign them from one value to another, or pass them into a method. This means that even if the value of firstCounter, secondCounter, or thirdCounter changes after calling DataTier.AddOurNumbers(), the values that your data tier has already recieved will not change.
Related
I am trying to create a global array using data from a file and use that array for calculations in different functions, e.g. a button click handler. When I use my calculation button it says 'Value cannot be null'.
public partial class Form1 : Form
{
double size = 0;
double[] temperture;
public Form1()
{
InitializeComponent();
OpenFileDialog fileDialog = new OpenFileDialog();
if (fileDialog.ShowDialog() == DialogResult.OK)
{
StreamReader sr = new StreamReader(fileDialog.OpenFile());
string line = sr.ReadLine();
double size = Convert.ToDouble(line);
//create array
double[] temperture = new double[(int)size];
for (int i = 0; i < size; i++)
{
line = sr.ReadLine();
//convert line to double and store in the array
temperture[i] = Convert.ToDouble(line);
}
}
}
private void calculateAverageTempertureToolStripMenuItem1_Click(object sender, System.EventArgs e)
{
double sum = temperture.Sum();
double average = ((double)sum) / temperture.Length;
textBox1.Text = "Average Temperature = " + average;
}
}
Don't redeclare a local variable for temperture:
double[] temperture = new double[(int)size];
Re-use the instance variable you already declared as an instance of the class:
temperture = new double[(int)size];
You are almost done!
Try not to put everything into one procedure.
Google for the SOLID principle and remember the S!
In your Form1 class you have fields: temperture and size. Before you display your form, you want to give these fields a value.
Ask operator for a file name
To calculate these values, you need a filename. You decided to ask the operator for the filename. So let's create small procedures in your Form1 class that will do this: one to ask for the filename, one to read the contents of the file and one to put this all together:
private string SelectFileName()
{
using (OpenFileDialog dlg = new OpenFileDialog())
{
// Set properties before showing the dialog, for example:
dlg.Title = "Please select a file";
dlg.CheckFileExists = true;
dlg.InitialDirectory = ...
// etc. Google: OpenFileDialog class
// show the dlg, and if user presses OK, return the filename, otherwise null
var dlgResult = dlg.ShowDialog(this);
if (dlgResult == DialogResult.Ok)
return dlg.FileName;
else
return null;
}
}
OpenFileDialog is Disposable. Remember to always put IDisposable objects inside a using statement, so you can be certain that it is disposed after use, even if an exception is thrown.
For properties see OpenFileDialog and the base class.
Read the file with Temperatures
After the operator selected a file, you can read it. Apparently the first line of the file contains the number of temperatures as a string, every next line contains every temperature in string format.
You decided to use two separate fields: size and temperature. Know that every array has a property length that holds the number of elements in the array, so you won't need field size.
Furthermore, my advice would be to use List<double> instead of double[]. Only use arrays if you know the size of the array before you create it, and if you are certain that you will never have to change the length. With Lists you won't have to care about the number of elements in it, if you add items, the list automatically changes size.
private List<double> Temperatures {get; set;}
(or if you want, make it a field: `private list temperatures;)
private List<double> ReadTemperatureFile(string fileName)
{
// TODO: decide what to do if fileName null, or if file does not exist
// return empty list? or throw ArgumentNullException and FileNotFoundException?
using (var textReader = File.OpenText(fileName))
{
// first line is the expected number of Temperatures in this file
string firstLine = textReader.ReadLine();
if (firstLine == null)
{
// There is no first line
// Todo: return empty array or throw DataNotFoundException?
}
// if here: the first line has been read
int expectedNumberOfTemperatures = Int32.Parse(firstLine);
List<double> temperatures = new List<double>(firstLine);
Actually, to create a List, you don't need to know how Long it will be. Adding the expected size to the constructor is only to improve performance.
If you are free to change the format of the temperature files, consider to remove the line with the number of elements and keep only the temperatures. This way, you can avoid the problem that the first line says that there are 100 temperatures, but the file only contains 50 temperature values.
By the way, only use Int32.Parse(firstLine) if you are absolutely certain that the first line can be parsed to an int. If you want to handle invalid file formats correctly, consider to use:
if (!Int32.TryParse(firstLine, out int expectedNumberOfTemperatures)
{
// TODO: handle invalid file format; return empty array?
// throw InvalidDataException?
}
List<double> temperatures = new List<double>(expectedNumberOfTemperatures);
By the way: the StreamReader that OpenText returns is IDisposable, so I wrapped it in a using statement.
Continuing reading the file:
string temperatureText = textReader.ReadLine();
while (temperatureText != null)
{
// a line has been read, convert to double and add to array
double temperature = Int32.Parse(temperatureText);
temperatures.Add(temperature);
temperaturText = textReader.ReadLine();
}
}
Did you see that I didn't care about the actual number of temperatures in the file? If the first line said that 100 temperatures are expected, but in fact there are 200 temperatures, I just read them all, and add them to the List. The List grows automatically when needed.
Of course, if you only want to read 100 temperatures, even if there are still temperatures left, then use a counter and stop when the expectedNumberOfTemperatures are read.
Only use Int32.Parse if you are certain that the file contains only valid temperatures, otherwise use Int32.TryParse and decide what to do if an invalid line has been read.
By the way, if you use LINQ, your procedure will be much smaller. Most programmers will immediately know what happens:
(assuming that you can change the file such that it only contains temperatures.)
private List<double> ReadTemperatureFile(string fileName)
{
return System.IO.File.ReadAllLines(fileName)
.Select(line => int32.Parse(line))
.ToList();
}
In words: read all lines that are in the text file with fileName. Parse every read line into a double and convert the sequence of parsed doubles to a List.
If you really want to return double[], replace the terminating ToList() with a ToArray()
Or if the first line has to hold the expected number of temperatures and you want to return all temperatures, skip the first line before you convert to doubles:
return System.IO.File.ReadAllLines(fileName)
.Skip(1)
.Select(line => int32.Parse(line))
.ToList();
Calculate Sum and Average of every sequence of doubles
To make this procedure more reusable, I won't make it only for Lists, or for Arrays, but for every sequence of doubles:
private void CalculateAverageTemperature(IEnumerable<double> temperatures)
{
// using LINQ make this a one-liner:
return temperatures.Average();
}
In fact, I wouldn't even bother to create a procedure for this.
Put it all together:
private void FillTemperatures()
{
string fileName = this.SelectFileName();
this.Temperatures = this.ReadTemperatureFile(fileName);
double averageTemperature = this.Temperatures.Average();
this.textBoxAverage.Text = averageTemperature.ToString(); }
}
And finally your event handler:
private void OnMenuItemCalculateAverage(object sender, ...)
{
this.FillTemperatures();
}
I separated the event handler from the actual data processing. If you decide to use a button to select a file and calculate an average, changes will be minimal
Conclusion
Because you separated your code into smaller procedures, that each have only one task, it is much easier for readers to understand what every procedure should do. For you it is much easier to unit test each procedure. If slight changes are needed, for instance you want a button instead of a menu item, or uses type the name of the file in a text box, or you want to support OpenFileDialog as well as a text box with the filename, changes are minimal.
Furthermore: always wrap disposables in a using statement. Use List<...> instead of array, and consider to use LINQ to process sequences of similar items.
Help me find out how to add the full array i created into one line, It looks like by changing the int to double to big error changes, so for now I just want to try to add everything on the whole line.
It seems when i try to add a array it prints out the name of the array, when i try to print out the array instance name it prints the file pathway, when i add split array[0] it successfully prints the first element in the array. How can I add the whole array and not just the first element?
This is what the text looks like:
regular,bread,2.00,2
regular,milk,2.00,3
This is what I want it to look like after coded
regular,bread,2.00,2,(the result of 2*2*GST)
regular,milk,2.00,3,(the result of 2*3*GST)
This is what I get it(dont need to show regular item cost string):
System.Collections.Generic.List`1[System.String]
RegularItemCost:
4.4
This is the code I have got for reading and the method and constructors for calculations:
public List<string> readFile()
{
string line = "";
StreamReader reader = new StreamReader("groceries.txt"); //variable reader to read file
while ((line = reader.ReadLine()) != null) //reader reads each line while the lines is not blank, line is assigned value of reader
{
line = line.Trim(); //gets rid of any spaces on each iteration within the line
if (line.Length > 0) //during each line the below actions are performed
{
string[] splitArray = line.Split(new char[] { ',' }); //creates a array called splitArray which splits each line into an array and a new char
type = splitArray[0]; // type is assigned for each line at position [0] on
name = splitArray[1]; //name is assigned at position [1]
//<<<-------food cost calculation methods initialized-------->>>>
RegularItem purchasedItem = new RegularItem(splitArray); //purchased Item is the each line to be printed
FreshItem freshItem = new FreshItem(splitArray);
double regCost = purchasedItem.getRegularCost(); //regCost will multiply array at position [2] with [3]
double freshCost = freshItem.getFreshItemCost();
string[] arrayList = { Convert.ToString(regCost), Convert.ToString(freshCost) };
List<string> newArray = new List<string>(splitArray);
newArray.AddRange(arrayList);
if (type == "regular")
{
// items.InsertRange(4, (arrayList)); //first write a line in the list with the each line written
items.Add(Convert.ToString(newArray));
items.Add("RegularItemCost:");
items.Add(Convert.ToString(regCost)); //next add the regCost method to write a line with the cost of that item
}
else if (type == "fresh")
{
items.Add(Convert.ToString(freshItem)); //first write a line in the list with the each line written
items.Add("FreshItemCost:");
items.Add(Convert.ToString(freshCost)); //next add the fresh method to write another line with the cost of that item
}
}
}
return items;
}
//constrctor and method
public class RegularItem : GroceryItem //inheriting properties from class GroceryItem
{
private string[] splitArray;
public RegularItem()
{
}
public RegularItem(string[] splitArray) //enables constructor for RegularItem to split into array
{
this.type = splitArray[0];
this.name = splitArray[1];
this.price = double.Parse(splitArray[2]); //each line at position 4 is a double
this.quantity = double.Parse(splitArray[3]); //each line at position 3 is parsed to an integer
}
public double getRegularCost() //method from cost of regular
{
return this.price * this.quantity * 1.1; //workout out cost for purchases including GST
}
}
Ok, multiple things. First, while it's not bad to use Convert. ToString(), i think is better to just do . ToString. Remember all objects inherit from object so all objects will have that method.
If you want all the values of a collection to be "joined" into one string beter use string. Join(), look at it, you can specify a separatorto use between values. If you just use the Convert. ToString() directly on the list it just print the information about the list object itself, not the values inside the list.
Next, if you use ToString or Convert. ToString with a built-in type like int or double, it will print the number as a string, but if you do it with your custom object or simply with a more conplex object like List it will just print the type info. To solve this in your custom objects (like RegularItem f. I.) you must override the ToString() method an code there what you want to print when the method get called. So you can override the method and put there to print the cost dor example.
I have 16 TextBox. Each TextBox should be updated with values (separated by comma).
public string DataReceived
{
get { return data_str; }
set
{
data_str = value;
string[] valori_separati = DataReceived.Split(',');
//valori_separati = DataReceived.Split(',');
try
{
int.TryParse(valori_separati[0], out Team_ID);
int.TryParse(valori_separati[1], out Mission_time);
double.TryParse(valori_separati[2], out Packet_count);
int.TryParse(valori_separati[3], out Alt_sensor);
double.TryParse(valori_separati[4], out Pressure);
double.TryParse(valori_separati[5], out Temp);
double.TryParse(valori_separati[6], out Voltage);
double.TryParse(valori_separati[7], out GPS_Time);
double.TryParse(valori_separati[8], out GPS_Latitude);
double.TryParse(valori_separati[9], out GPS_Longitude);
double.TryParse(valori_separati[10], out GPS_Altitude);
int.TryParse(valori_separati[11], out GPS_Sats);
double.TryParse(valori_separati[12], out TILT_X);
double.TryParse(valori_separati[13], out TILT_Y);
double.TryParse(valori_separati[14], out TILT_Z);
int.TryParse(valori_separati[15], out Software_state);
}
catch (IndexOutOfRangeException)
{
packet_loss = packet_loss + 1;
}
if (packet_loss >= 5)
{
BeginInvoke((Action)(() => fr1.Show()));
}
updateTextboxDelegate fillTextbox = updateTextbox;
this.Invoke(fillTextbox);
}
}
private void updateTextbox()
{
Data_ID_Glider.Text = Team_ID.ToString();
DataMssTime.Text = Mission_time.ToString();
Data_Pack.Text = Packet_count.ToString();
Data_Alt.Text = Alt_sensor.ToString();
Data_Press.Text = Pressure.ToString();
GpsTime.Text = GPS_Time.ToString();
Data_Temp.Text = Temp.ToString();
Data_Voltage.Text = Voltage.ToString();
Data_Sw_St.Text = Software_state.ToString();
[...]
}
By this way decimal values are not shown. I mean that only numbers, without their decimals, are shown. I tried to update the textbox inside the datareceived but thread exception is called. How should I do that?
After casting most of the values into double, you are using double.ToString() method to convert it into a string. This truncates the decimal part of the double value.
There are many string formatters that you can use to format the double value according to your needs.
For example you can try
Data_ID_Glider.Text = Team_ID.ToString("F");
The above will assign the value of Team_ID with 3 decimal places. For more such specifiers you can take a look here
https://msdn.microsoft.com/en-us/library/kfsatb94(v=vs.110).aspx
I solved the problem using this method:
double.TryParse(valori_separati[12],NumberStyles.Number, CultureInfo.CreateSpecificCulture ("en-US"), out TILT_X);
and so on with the other array arguments.
This is the structure:
public struct ProfilePoint
{
public double x;
public double z;
byte intensity;
}
It is used inside a callback function (I deleted most of it so it won't make sense, there is a for loop that cycle through every points (arrayIndex) that were scanned on a surface and process them. The result is stored inside profileBuffer):
public static void onData(KObject data)
{
if (points[arrayIndex].x != -32768)
{
profileBuffer[arrayIndex].x = 34334;
profileBuffer[arrayIndex].z = 34343;
validPointCount++;
}
else
{
profileBuffer[arrayIndex].x = 32768;
profileBuffer[arrayIndex].z = 32768;
}
}
}
I would like to process the data inside profileBuffer (both array, x & z).
So far I was "able" to create a function that get one value from profileBuffer with no error from visual studio:
public static int ProcessProfile(double dataProfile)
{
int test=1;
return test;
}
Putting this line:
ProcessProfile(profileBuffer[1].x);
Into onData() result in no error but that's just one value. Ideally, I would like to have the whole array. What confuse me is that every value stored inside profileBuffer are double (forget intensity). But stored in array. Yet I can't import the data like ProcessProfile(profileBuffer.x); I have to specify an index... Is it possible to manipulate a vector (line) of data? That would be ideal for me.
Sorry for the poor explanation / long post... I am quite newb.
you need
public static int ProcessProfile(ProfilePoint []points)
{
var x = points[4].x;
.....
}
and do
ProcessProfile(profileBuffer);
I am new to programming in C# and I'm having problems generating random numbers from input read form a file. I am trying to generate random numbers from the second field on each line from the following input read from a text file
4321,99
5432,79
6543,59
7654,39
The file is read by the following code, then parsed into separate fields where a method is called to generate a random number
private void readFileButton_Click(object sender, EventArgs e)
{
string readString;
inputFile = File.OpenText(sourceFileString);
while (!inputFile.EndOfStream)
{
readString = inputFile.ReadLine();
var flds = readString.Split(',');
string patID = flds[0];
int months = Convert.ToInt32(flds[1]);
Random();
}
inputFile.Close();
}
The method I am using that generates a random number from the second field
private void Random()
{
Random rand2Integer = new Random();
randomInteger = rand2Integer.Next(1, months) + 1;
}
However, this exception is thrown: 'minValue' cannot be greater than maxValue, and I can't wrap my head around it. If I manually enter the data on a form using a text box then the random number is generated as expected. Any input to guide me along?
From your code it looks like you have a class variable months. However, while reading file you have declared a local variable which essentially hides the class variable.
Now when you use Random function, the class variable is used (which must have 0 and causing this error)
replace the following line of code
int months = Convert.ToInt32(flds[1]);
with
months = Convert.ToInt32(flds[1]);
The variable months in Random() is not the same that the one you are assigning in int months = Convert.ToInt32(flds[1]); the last is local to the method.
You should define month outside or pass it as a parameter to Random()
EDIT:
I made minor changes to make code easier to read. Hope it helps.
private void readFileButton_Click(object sender, EventArgs e)
{
// If you use the stream this way it will be disposed automatically.
using (var sr = new StreamReader(sourceFileString))
{
while (!sr.EndOfStream)
{
string readString = sr.ReadLine();
var flds = readString.Split(',');
string patID = flds[0];
int months = int.Parse(flds[1]);
//I prefer parameters more than fields to communicate between methods.
Random(months);
}
}
}
Random randomGenerator = new Random();
private void Random(int months)
{
randomInteger = randomGenerator.Next(1, months) + 1;
}
In the readFile function, you declare a variable called months and initialize it to the number from your file. This appears correct and probably works great.
However, that variable has function scope. You likely have another variable called "months" at the class level (otherwise you would be getting a compile time error). This variable, and not the one set in "readFile", is what is used by the "Random" method. Change the line to:
months = Convert.ToInt32(flds[1]);
and it will work.
As an aside, you should not use a new instance of Random every time you need a draw. It is considered better practice to have one instance per object and reuse it each time you need a new random number.