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  • C# Convert string to nullable type (int, double, etc...)

    - by Nathan Koop
    I am attempting to do some data conversion. Unfortunately, much of the data is in strings, where it should be int's or double, etc... So what I've got is something like: double? amount = Convert.ToDouble(strAmount); The problem with this approach is if strAmount is empty, if it's empty I want it to amount to be null, so when I add it into the database the column will be null. So I ended up writing this: double? amount = null; if(strAmount.Trim().Length>0) { amount = Convert.ToDouble(strAmount); } Now this works fine, but I now have five lines of code instead of one. This makes things a little more difficult to read, especially when I have a large amount of columns to convert. I thought I'd use an extension to the string class and generic's to pass in the type, this is because it could be a double, or an int, or a long. So I tried this: public static class GenericExtension { public static Nullable<T> ConvertToNullable<T>(this string s, T type) where T: struct { if (s.Trim().Length > 0) { return (Nullable<T>)s; } return null; } } But I get the error: Cannot convert type 'string' to 'T?' Is there a way around this? I am not very familiar with creating methods using generics.

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  • C#/.NET Little Pitfalls: The Dangers of Casting Boxed Values

    - by James Michael Hare
    Starting a new series to parallel the Little Wonders series.  In this series, I will examine some of the small pitfalls that can occasionally trip up developers. Introduction: Of Casts and Conversions What happens when we try to assign from an int and a double and vice-versa? 1: double pi = 3.14; 2: int theAnswer = 42; 3:  4: // implicit widening conversion, compiles! 5: double doubleAnswer = theAnswer; 6:  7: // implicit narrowing conversion, compiler error! 8: int intPi = pi; As you can see from the comments above, a conversion from a value type where there is no potential data loss is can be done with an implicit conversion.  However, when converting from one value type to another may result in a loss of data, you must make the conversion explicit so the compiler knows you accept this risk.  That is why the conversion from double to int will not compile with an implicit conversion, we can make the conversion explicit by adding a cast: 1: // explicit narrowing conversion using a cast, compiler 2: // succeeds, but results may have data loss: 3: int intPi = (int)pi; So for value types, the conversions (implicit and explicit) both convert the original value to a new value of the given type.  With widening and narrowing references, however, this is not the case.  Converting reference types is a bit different from converting value types.  First of all when you perform a widening or narrowing you don’t really convert the instance of the object, you just convert the reference itself to the wider or narrower reference type, but both the original and new reference type both refer back to the same object. Secondly, widening and narrowing for reference types refers the going down and up the class hierarchy instead of referring to precision as in value types.  That is, a narrowing conversion for a reference type means you are going down the class hierarchy (for example from Shape to Square) whereas a widening conversion means you are going up the class hierarchy (from Square to Shape).  1: var square = new Square(); 2:  3: // implicitly convers because all squares are shapes 4: // (that is, all subclasses can be referenced by a superclass reference) 5: Shape myShape = square; 6:  7: // implicit conversion not possible, not all shapes are squares! 8: // (that is, not all superclasses can be referenced by a subclass reference) 9: Square mySquare = (Square) myShape; So we had to cast the Shape back to Square because at that point the compiler has no way of knowing until runtime whether the Shape in question is truly a Square.  But, because the compiler knows that it’s possible for a Shape to be a Square, it will compile.  However, if the object referenced by myShape is not truly a Square at runtime, you will get an invalid cast exception. Of course, there are other forms of conversions as well such as user-specified conversions and helper class conversions which are beyond the scope of this post.  The main thing we want to focus on is this seemingly innocuous casting method of widening and narrowing conversions that we come to depend on every day and, in some cases, can bite us if we don’t fully understand what is going on!  The Pitfall: Conversions on Boxed Value Types Can Fail What if you saw the following code and – knowing nothing else – you were asked if it was legal or not, what would you think: 1: // assuming x is defined above this and this 2: // assignment is syntactically legal. 3: x = 3.14; 4:  5: // convert 3.14 to int. 6: int truncated = (int)x; You may think that since x is obviously a double (can’t be a float) because 3.14 is a double literal, but this is inaccurate.  Our x could also be dynamic and this would work as well, or there could be user-defined conversions in play.  But there is another, even simpler option that can often bite us: what if x is object? 1: object x; 2:  3: x = 3.14; 4:  5: int truncated = (int) x; On the surface, this seems fine.  We have a double and we place it into an object which can be done implicitly through boxing (no cast) because all types inherit from object.  Then we cast it to int.  This theoretically should be possible because we know we can explicitly convert a double to an int through a conversion process which involves truncation. But here’s the pitfall: when casting an object to another type, we are casting a reference type, not a value type!  This means that it will attempt to see at runtime if the value boxed and referred to by x is of type int or derived from type int.  Since it obviously isn’t (it’s a double after all) we get an invalid cast exception! Now, you may say this looks awfully contrived, but in truth we can run into this a lot if we’re not careful.  Consider using an IDataReader to read from a database, and then attempting to select a result row of a particular column type: 1: using (var connection = new SqlConnection("some connection string")) 2: using (var command = new SqlCommand("select * from employee", connection)) 3: using (var reader = command.ExecuteReader()) 4: { 5: while (reader.Read()) 6: { 7: // if the salary is not an int32 in the SQL database, this is an error! 8: // doesn't matter if short, long, double, float, reader [] returns object! 9: total += (int) reader["annual_salary"]; 10: } 11: } Notice that since the reader indexer returns object, if we attempt to convert using a cast to a type, we have to make darn sure we use the true, actual type or this will fail!  If the SQL database column is a double, float, short, etc this will fail at runtime with an invalid cast exception because it attempts to convert the object reference! So, how do you get around this?  There are two ways, you could first cast the object to its actual type (double), and then do a narrowing cast to on the value to int.  Or you could use a helper class like Convert which analyzes the actual run-time type and will perform a conversion as long as the type implements IConvertible. 1: object x; 2:  3: x = 3.14; 4:  5: // if you want to cast, must cast out of object to double, then 6: // cast convert. 7: int truncated = (int)(double) x; 8:  9: // or you can call a helper class like Convert which examines runtime 10: // type of the value being converted 11: int anotherTruncated = Convert.ToInt32(x); Summary You should always be careful when performing a conversion cast from values boxed in object that you are actually casting to the true type (or a sub-type). Since casting from object is a widening of the reference, be careful that you either know the exact, explicit type you expect to be held in the object, or instead avoid the cast and use a helper class to perform a safe conversion to the type you desire. Technorati Tags: C#,.NET,Pitfalls,Little Pitfalls,BlackRabbitCoder

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  • Is there a way to make 7zip temporarly uncompress the whole archive when double-clicking on an exe?

    - by Gnoupi
    In WinRAR, one feature which I like is the fact that you can set it to uncompress the whole archive in a temporary place, if you double-click on an .exe file inside the archive opened in WinRAR. Typically, I often download small games, which I just want to try, without the hassle of creating a folder for it, etc. Same for archives containing an installer with its own separate files. In the 7-zip window, if I double-click an exe, it will just extract the exe in a temporary location and launch it. In the small game context (or installer), it means that it will simply fail, because it will miss required files in the same folder. So my question is: Is there a way to make 7-zip extract the whole archive in a temporary folder when launching an exe from inside the archive?

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  • changing value of a textview while change in other textview by multiplying

    - by sur007
    Here I am getting parsed data from a URL and now I am trying to change the value of parse data to users only dynamically on an text view and my code is package com.mokshya.jsontutorial; import java.text.DecimalFormat; import java.util.ArrayList; import java.util.HashMap; import org.json.JSONArray; import org.json.JSONException; import org.json.JSONObject; import org.w3c.dom.Document; import org.w3c.dom.Element; import org.w3c.dom.NodeList; import com.mokshya.jsontutorialhos.xmltest.R; import android.app.AlertDialog; import android.app.ListActivity; import android.content.DialogInterface; import android.content.Intent; import android.os.Bundle; import android.text.Editable; import android.text.TextWatcher; import android.util.Log; import android.view.View; import android.widget.AdapterView; import android.widget.AdapterView.OnItemClickListener; import android.widget.EditText; import android.widget.ListAdapter; import android.widget.ListView; import android.widget.SimpleAdapter; import android.widget.TextView; import android.widget.Toast; public class Main extends ListActivity { EditText resultTxt; public double C_webuserDouble; public double C_cashDouble; public double C_transferDouble; public double S_webuserDouble; public double S_cashDouble; public double S_transferDouble; TextView cashTxtView; TextView webuserTxtView; TextView transferTxtView; TextView S_cashTxtView; TextView S_webuserTxtView; TextView S_transferTxtView; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.listplaceholder); cashTxtView = (TextView) findViewById(R.id.cashTxtView); webuserTxtView = (TextView) findViewById(R.id.webuserTxtView); transferTxtView = (TextView) findViewById(R.id.transferTxtView); S_cashTxtView = (TextView) findViewById(R.id.S_cashTxtView); S_webuserTxtView = (TextView) findViewById(R.id.S_webuserTxtView); S_transferTxtView = (TextView) findViewById(R.id.S_transferTxtView); ArrayList<HashMap<String, String>> mylist = new ArrayList<HashMap<String, String>>(); JSONObject json = JSONfunctions .getJSONfromURL("http://ldsclient.com/ftp/strtojson.php"); try { JSONArray netfoxlimited = json.getJSONArray("netfoxlimited"); for (inti = 0; i < netfoxlimited.length(); i++) { HashMap<String, String> map = new HashMap<String, String>(); JSONObject e = netfoxlimited.getJSONObject(i); map.put("date", e.getString("date")); map.put("c_web", e.getString("c_web")); map.put("c_bank", e.getString("c_bank")); map.put("c_cash", e.getString("c_cash")); map.put("s_web", e.getString("s_web")); map.put("s_bank", e.getString("s_bank")); map.put("s_cash", e.getString("s_cash")); mylist.add(map); } } catch (JSONException e) { Log.e("log_tag", "Error parsing data " + e.toString()); } ListAdapter adapter = new SimpleAdapter(this, mylist, R.layout.main, new String[] { "date", "c_web", "c_bank", "c_cash", "s_web", "s_bank", "s_cash", }, new int[] { R.id.item_title, R.id.webuserTxtView, R.id.transferTxtView, R.id.cashTxtView, R.id.S_webuserTxtView, R.id.S_transferTxtView, R.id.S_cashTxtView }); setListAdapter(adapter); final ListView lv = getListView(); lv.setTextFilterEnabled(true); lv.setOnItemClickListener(new OnItemClickListener() { public void onItemClick(AdapterView<?> parent, View view, int position, long id) { @SuppressWarnings("unchecked") HashMap<String, String> o = (HashMap<String, String>) lv .getItemAtPosition(position); Toast.makeText(Main.this, "ID '" + o.get("id") + "' was clicked.", Toast.LENGTH_SHORT).show(); } }); resultTxt = (EditText) findViewById(R.id.editText1); resultTxt.setOnClickListener(new View.OnClickListener() { public void onClick(View arg0) { // TODO Auto-generated method stub resultTxt.setText(""); } }); resultTxt.addTextChangedListener(new TextWatcher() { public void afterTextChanged(Editable arg0) { // TODO Auto-generated method stub String text; text = resultTxt.getText().toString(); if (resultTxt.getText().length() > 5) { calculateSum(C_webuserDouble, C_cashDouble, C_transferDouble); calculateSunrise(S_webuserDouble, S_cashDouble, S_transferDouble); } else { } } public void beforeTextChanged(CharSequence s, int start, int count, int after) { // TODO Auto-generated method stub } public void onTextChanged(CharSequence s, int start, int before, int count) { // TODO Auto-generated method stub } }); } private void calculateSum(Double webuserDouble, Double cashDouble, Double transferDouble) { String Qty; Qty = resultTxt.getText().toString(); if (Qty.length() > 0) { double QtyValue = Double.parseDouble(Qty); double cashResult; double webuserResult; double transferResult; cashResult = cashDouble * QtyValue; webuserResult = webuserDouble * QtyValue; transferResult = transferDouble * QtyValue; DecimalFormat df = new DecimalFormat("#.##"); String cashResultStr = df.format(cashResult); String webuserResultStr = df.format(webuserResult); String transferResultStr = df.format(transferResult); cashTxtView.setText(String.valueOf(cashResultStr)); webuserTxtView.setText(String.valueOf(webuserResultStr)); transferTxtView.setText(String.valueOf(transferResultStr)); // cashTxtView.setFilters(new InputFilter[] {new // DecimalDigitsInputFilter(2)}); } if (Qty.length() == 0) { cashTxtView.setText(String.valueOf(cashDouble)); webuserTxtView.setText(String.valueOf(webuserDouble)); transferTxtView.setText(String.valueOf(transferDouble)); } } private void calculateSunrise(Double webuserDouble, Double cashDouble, Double transferDouble) { String Qty; Qty = resultTxt.getText().toString(); if (Qty.length() > 0) { double QtyValue = Double.parseDouble(Qty); double cashResult; double webuserResult; double transferResult; cashResult = cashDouble * QtyValue; webuserResult = webuserDouble * QtyValue; transferResult = transferDouble * QtyValue; DecimalFormat df = new DecimalFormat("#.##"); String cashResultStr = df.format(cashResult); String webuserResultStr = df.format(webuserResult); String transferResultStr = df.format(transferResult); S_cashTxtView.setText(String.valueOf(cashResultStr)); S_webuserTxtView.setText(String.valueOf(webuserResultStr)); S_transferTxtView.setText(String.valueOf(transferResultStr)); } if (Qty.length() == 0) { S_cashTxtView.setText(String.valueOf(cashDouble)); S_webuserTxtView.setText(String.valueOf(webuserDouble)); S_transferTxtView.setText(String.valueOf(transferDouble)); } } } and I am getting following error on logcat 08-28 15:04:12.839: E/AndroidRuntime(584): Uncaught handler: thread main exiting due to uncaught exception 08-28 15:04:12.848: E/AndroidRuntime(584): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mokshya.jsontutorialhos.xmltest/com.mokshya.jsontutorial.Main}: java.lang.NullPointerException 08-28 15:04:12.848: E/AndroidRuntime(584): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2401) 08-28 15:04:12.848: E/AndroidRuntime(584): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2417) 08-28 15:04:12.848: E/AndroidRuntime(584): at android.app.ActivityThread.access$2100(ActivityThread.java:116) 08-28 15:04:12.848: E/AndroidRuntime(584): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1794) 08-28 15:04:12.848: E/AndroidRuntime(584): at android.os.Handler.dispatchMessage(Handler.java:99) 08-28 15:04:12.848: E/AndroidRuntime(584): at android.os.Looper.loop(Looper.java:123) 08-28 15:04:12.848: E/AndroidRuntime(584): at android.app.ActivityThread.main(ActivityThread.java:4203) 08-28 15:04:12.848: E/AndroidRuntime(584): at java.lang.reflect.Method.invokeNative(Native Method) 08-28 15:04:12.848: E/AndroidRuntime(584): at java.lang.reflect.Method.invoke(Method.java:521) 08-28 15:04:12.848: E/AndroidRuntime(584): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791) 08-28 15:04:12.848: E/AndroidRuntime(584): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:549) 08-28 15:04:12.848: E/AndroidRuntime(584): at dalvik.system.NativeStart.main(Native Method) 08-28 15:04:12.848: E/AndroidRuntime(584): Caused by: java.lang.NullPointerException 08-28 15:04:12.848: E/AndroidRuntime(584): at com.mokshya.jsontutorial.Main.onCreate(Main.java:111) 08-28 15:04:12.848: E/AndroidRuntime(584): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1123) 08-28 15:04:12.848: E/AndroidRuntime(584): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2364)

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  • When is a>a true ?

    - by Cricri
    Right, I think I really am living a dream. I have the following piece of code which I compile and run on an AIX machine: AIX 3 5 PowerPC_POWER5 processor type IBM XL C/C++ for AIX, V10.1 Version: 10.01.0000.0003 #include <stdio.h> #include <math.h> #define RADIAN(x) ((x) * acos(0.0) / 90.0) double nearest_distance(double radius,double lon1, double lat1, double lon2, double lat2){ double rlat1=RADIAN(lat1); double rlat2=RADIAN(lat2); double rlon1=lon1; double rlon2=lon2; double a=0,b=0,c=0; a = sin(rlat1)*sin(rlat2)+ cos(rlat1)*cos(rlat2)*cos(rlon2-rlon1); printf("%lf\n",a); if (a > 1) { printf("aaaaaaaaaaaaaaaa\n"); } b = acos(a); c = radius * b; return radius*(acos(sin(rlat1)*sin(rlat2)+ cos(rlat1)*cos(rlat2)*cos(rlon2-rlon1))); } int main(int argc, char** argv) { nearest_distance(6367.47,10,64,10,64); return 0; } Now, the value of 'a' after the calculation is reported as being '1'. And, on this AIX machine, it looks like 1 1 is true as my 'if' is entered !!! And my acos of what I think is '1' returns NanQ since 1 is bigger than 1. May I ask how that is even possible ? I do not know what to think anymore ! The code works just fine on other architectures where 'a' really takes the value of what I think is 1 and acos(a) is 0.

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  • C lang. -- Error: Segmentation fault

    - by user233542
    I don't understand why this would give me a seg fault. Any ideas? This is the function that returns the signal to stop the program (plus the other function that is called within this): double bisect(double A0,double A1,double Sol[N],double tol,double c) { double Amid,shot; while (A1-A0 > tol) { Amid = 0.5*(A0+A1); shot = shoot(Sol, Amid, c); if (shot==2.*Pi) { return Amid; } if (shot > 2.*Pi){ A1 = Amid; } else if (shot < 2.*Pi){ A0 = Amid; } } return 0.5*(A1+A0); } double shoot(double Sol[N],double A,double c) { int i,j; /*Initial Conditions*/ for (i=0;i<buff;i++) { Sol[i] = 0.; } for (i=buff+l;i<N;i++) { Sol[i] = 2.*Pi; } Sol[buff]= 0; Sol[buff+1]= A*exp(sqrt(1+3*c)*dx); for (i=buff+2;i<buff+l;i++) { Sol[i] = (dx*dx)*( sin(Sol[i-1]) + c*sin(3.*(Sol[i-1])) ) - Sol[i-2] + 2.*Sol[i-1]; } return Sol[i-1]; } The values buff, l, N are defined using a #define statement. l = 401, buff = 50, N = 2000

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  • Print array variables when using or not using double quotes.

    - by Nano HE
    Hi, When I learning to print array variables, I found the white space inserted when double quoter used. Snippet code as below. Could you please tell me why? #!/usr/bin/perl -w use strict; use warnings; my @str_array = ("Perl","array","tutorial"); my @int_array = (5,7,9,10); print @str_array; print "\n"; # added the double quotes print "@str_array"; print "\n"; print @int_array; print "\n"; # added the double quotes print "@int_array"; Output: Perlarraytutorial Perl array tutorial 57910 5 7 9 10

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  • How is conversion of float/double to int handled in printf?

    - by Sandip
    Consider this program int main() { float f = 11.22; double d = 44.55; int i,j; i = f; //cast float to int j = d; //cast double to int printf("i = %d, j = %d, f = %d, d = %d", i,j,f,d); //This prints the following: // i = 11, j = 44, f = -536870912, d = 1076261027 return 0; } Can someone explain why the casting from double/float to int works correctly in the first case, and does not work when done in printf? This program was compiled on gcc-4.1.2 on 32-bit linux machine.

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  • How can I find all attributes with single quotes in a Sublime Text 2 document and replace with double quotes?

    - by Brandon Durham
    I'm feeling particularly nit-picky today. I'm working in some HTML docs that have single quotes around all attribute values through the docs, like this: <div class='classone classtwo'> I'd love to be able to do a find-and-replace in each doc and replace with double quotes, like this: <div class="classone classtwo"> Many elements in the document will have multiple attributes: <div class='classone classtwo' data-scripts='lazyload'> And some will have the correct double quotes: <div class='classone classtwo' data-scripts="lazyload"> What's the best way to replace all single quotes wrapping values with double?

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  • How can i handle mouse double click event on textbox?

    - by Kar Cheng
    Hello, I want to open one child window on mouse double click of textbox. I know the only event available in Silverlight is MouseLeftButtonDown and you have to simulate double click. However it still doesn't work when i click in the middle of the textbox. It only works when i double click on the border of the textbox. Anybody has any ideas of how can i do this? If any 3rd party library is available then also it's fine. Thanks in advance:)

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  • Why does DateTime to Unix time use a double instead of an integer?

    - by Earlz
    I'm needing to convert a DateTime to a Unix timestamp. So I googled it looking for some example code In just about all the results I see, they use double as the return for such a function, even when explicitly using floor to convert it to an integer. Unix timestamps are always integers. So what problem is there with using either long or int instead of double? static double ConvertToUnixTimestamp(DateTime date) { DateTime origin = new DateTime(1970, 1, 1, 0, 0, 0, 0); TimeSpan diff = date - origin; return Math.Floor(diff.TotalSeconds); }

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  • How to determine if a decimal/double is an integer?

    - by Jim Geurts
    How do I tell if a decimal or double is an integer? For example: decimal d = 5.0; // Would be true decimal f = 5.5; // Would be false or double d = 5.0; // Would be true double f = 5.5; // Would be false The reason I would like to know this, is so that I can determine programmatically if I want to output the value using .ToString("N0") or .ToString("N2"). If there is no decimal point value, then I don't want to show that.

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  • How to create a generic C# method that can return either double or decimal?

    - by CrimsonX
    I have a method like this: private static double ComputePercentage(ushort level, ushort capacity) { double percentage; if(capacity == 1) percentage = 1; // do calculations... return percentage; } Is it possible to make it of a generic type like "type T" where it can return either decimal or double, depending on the type of method expected (or the type put into the function?) I tried something like this and I couldn't get it to work, because I cannot assign a number like "1" to a generic type. I also tried using the "where T :" after ushort capacity) but I still couldn't figure it out. private static T ComputePercentage<T>(ushort level, ushort capacity) { T percentage; if(capacity == 1) percentage = 1; // error here // do calculations... return percentage; } Is this even possible? I wasn't sure, but I thought this post might suggest that what I'm trying to do is just plain impossible.

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  • Does Oracle 10g automatically escape double quotes in recordsets?

    - by bitstream
    I am encountering an interesting issue with an application that was migrated from Oracle 9i to 10g. Previously, we had a problem when a field contained double quotes since Oracle recordsets encapsulated fields in double quotes. Example: "field1"||"field2"||"field "Y" 3"||"field4" Since the move to 10g, I believe that the Oracle client-side driver is parsing the double quotes and replacing them with &quot; Unfortunately I don't have an old 9i environment to test my theory. Have you seen similar behavior or can someone validate if my theory is true?

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  • Defining a Class in Objective C, XCode

    - by Brett
    Hello; I am new to Objective C, and am trying to write a class that defines a complex number. The code seems fine but when I print to the console, my values for instance variables are 0. Here is the code: // // ComplexNumber.h // Mandelbrot Set // // Created by Brett on 10-06-02. // Copyright 2010 __MyCompanyName__. All rights reserved. // #import <Foundation/Foundation.h> #import <stdio.h> @interface ComplexNumber : NSObject { double real; double imaginary; } // Getters -(double) real; -(double) imaginary; // Setters -(void)setReal: (double) a andImaginary: (double) b; //Function -(ComplexNumber *)squared; @end // // ComplexNumber.m // Mandelbrot Set // // Created by Brett on 10-06-02. // Copyright 2010 __MyCompanyName__. All rights reserved. // #import "ComplexNumber.h" #import <math.h> #import <stdio.h> @implementation ComplexNumber -(double)real{ return self->real; } -(double)imaginary{ return self->imaginary; } -(void)setReal: (double) a andImaginary: (double) b{ self->real=a; self->imaginary=b; } -(ComplexNumber *)squared{ double a = pow(real,2); double b = pow(imaginary, 2); double c = 2*real*imaginary; ComplexNumber *d; [d setReal:(a-b) andImaginary: c]; return d; } @end In the App Delegate for debugging purposes I added: - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { ComplexNumber *testNumber = [[ComplexNumber alloc] init]; [testNumber setReal:55.0 andImaginary:30.0]; NSLog(@"%d", testNumber.real); // Override point for customization after app launch [window addSubview:viewController.view]; [window makeKeyAndVisible]; return YES; } But the console returns 0 everytime. Help?

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  • Help with method logic in Java, hw

    - by Crystal
    I have a Loan class that in its printPayment method, it prints the amortization table of a loan for a hw assignment. We are also to implement a print first payment method, and a print last payment method. Since my calculation is done in the printPayment method, I didn't know how I could get the value in the first or last iteration of the loop and print that amount out. One way I can think of is to write a new method that might return that value, but I wasn't sure if there was a better way. Here is my code: public abstract class Loan { public void setClient(Person client) { this.client = client; } public Person getClient() { return client; } public void setLoanId() { loanId = nextId; nextId++; } public int getLoanId() { return loanId; } public void setInterestRate(double interestRate) { this.interestRate = interestRate; } public double getInterestRate() { return interestRate; } public void setLoanLength(int loanLength) { this.loanLength = loanLength; } public int getLoanLength() { return loanLength; } public void setLoanAmount(double loanAmount) { this.loanAmount = loanAmount; } public double getLoanAmount() { return loanAmount; } public void printPayments() { double monthlyInterest; double monthlyPrincipalPaid; double newPrincipal; int paymentNumber = 1; double monthlyInterestRate = interestRate / 1200; double monthlyPayment = loanAmount * (monthlyInterestRate) / (1 - Math.pow((1 + monthlyInterestRate),( -1 * loanLength))); System.out.println("Payment Number | Interest | Principal | Loan Balance"); // amortization table while (loanAmount >= 0) { monthlyInterest = loanAmount * monthlyInterestRate; monthlyPrincipalPaid = monthlyPayment - monthlyInterest; newPrincipal = loanAmount - monthlyPrincipalPaid; loanAmount = newPrincipal; System.out.printf("%d, %.2f, %.2f, %.2f", paymentNumber++, monthlyInterest, monthlyPrincipalPaid, loanAmount); } } /* //method to print first payment public double getFirstPayment() { } method to print last payment public double getLastPayment() { }*/ private Person client; private int loanId; private double interestRate; private int loanLength; private double loanAmount; private static int nextId = 1; } Thanks!

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  • fatal error C1075: end of file found before the left brace and read and write files not working

    - by user320950
    could someone also tell me if the actions i am attempting to do which are stated in the comments are correct or not. i am new at c++ and i think its correct but i have doubts #include<iostream> #include<fstream> #include<cstdlib> #include<iomanip> using namespace std; int main() { ifstream in_stream; // reads itemlist.txt ofstream out_stream1; // writes in items.txt ifstream in_stream2; // reads pricelist.txt ofstream out_stream3;// writes in plist.txt ifstream in_stream4;// read recipt.txt ofstream out_stream5;// write display.txt float price=' ',curr_total=0.0; int wrong=0; int itemnum=' '; char next; in_stream.open("ITEMLIST.txt", ios::in); // list of avaliable items if( in_stream.fail() )// check to see if itemlist.txt is open { wrong++; cout << " the error occured here0, you have " << wrong++ << " errors" << endl; cout << "Error opening the file\n" << endl; exit(1); } else{ cout << " System ran correctly " << endl; out_stream1.open("listWititems.txt", ios::out); // list of avaliable items if(out_stream1.fail() )// check to see if itemlist.txt is open { wrong++; cout << " the error occured here1, you have " << wrong++ << " errors" << endl; cout << "Error opening the file\n"; exit(1); } else{ cout << " System ran correctly " << endl; } in_stream2.open("PRICELIST.txt", ios::in); if( in_stream2.fail() ) { wrong++; cout << " the error occured here2, you have " << wrong++ << " errors" << endl; cout << "Error opening the file\n"; exit (1); } else{ cout << " System ran correctly " << endl; } out_stream3.open("listWitdollars.txt", ios::out); if(out_stream3.fail() ) { wrong++; cout << " the error occured here3, you have " << wrong++ << " errors" << endl; cout << "Error opening the file\n"; exit (1); } else{ cout << " System ran correctly " << endl; } in_stream4.open("display.txt", ios::in); if( in_stream4.fail() ) { wrong++; cout << " the error occured here4, you have " << wrong++ << " errors" << endl; cout << "Error opening the file\n"; exit (1); } else{ cout << " System ran correctly " << endl; } out_stream5.open("showitems.txt", ios::out); if( out_stream5.fail() ) { wrong++; cout << " the error occured here5, you have " << wrong++ << " errors" << endl; cout << "Error opening the file\n"; exit (1); } else{ cout << " System ran correctly " << endl; } in_stream.close(); // closing files. out_stream1.close(); in_stream2.close(); out_stream3.close(); in_stream4.close(); out_stream5.close(); system("pause"); in_stream.setf(ios::fixed); while(in_stream.eof()) { in_stream >> itemnum; cin.clear(); cin >> next; } out_stream1.setf(ios::fixed); while (out_stream1.eof()) { out_stream1 << itemnum; cin.clear(); cin >> next; } in_stream2.setf(ios::fixed); in_stream2.setf(ios::showpoint); in_stream2.precision(2); while((price== (price*1.00)) && (itemnum == (itemnum*1))) { while (in_stream2 >> itemnum >> price) // gets itemnum and price { while (in_stream2.eof()) // reads file to end of file { in_stream2 >> itemnum; in_stream2 >> price; price++; curr_total= price++; in_stream2 >> curr_total; cin.clear(); // allows more reading cin >> next; } } } out_stream3.setf(ios::fixed); out_stream3.setf(ios::showpoint); out_stream3.precision(2); while((price== (price*1.00)) && (itemnum == (itemnum*1))) { while (out_stream3 << itemnum << price) { while (out_stream3.eof()) // reads file to end of file { out_stream3 << itemnum; out_stream3 << price; price++; curr_total= price++; out_stream3 << curr_total; cin.clear(); // allows more reading cin >> next; } return itemnum, price; } } in_stream4.setf(ios::fixed); in_stream4.setf(ios::showpoint); in_stream4.precision(2); while ( in_stream4.eof()) { in_stream4 >> itemnum >> price >> curr_total; cin.clear(); cin >> next; } out_stream5.setf(ios::fixed); out_stream5.setf(ios::showpoint); out_stream5.precision(2); out_stream5 <<setw(5)<< " itemnum " <<setw(5)<<" price "<<setw(5)<<" curr_total " <<endl; // sends items and prices to receipt.txt out_stream5 << setw(5) << itemnum << setw(5) <<price << setw(5)<< curr_total; // sends items and prices to receipt.txt out_stream5 << " You have a total of " << wrong++ << " errors " << endl; }

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  • Hierarchy flattening of interfaces in WCF

    - by nmarun
    Alright, so say I have my service contract interface as below: 1: [ServiceContract] 2: public interface ILearnWcfService 3: { 4: [OperationContract(Name = "AddInt")] 5: int Add(int arg1, int arg2); 6: } Say I decided to add another interface with a similar add “feature”. 1: [ServiceContract] 2: public interface ILearnWcfServiceExtend : ILearnWcfService 3: { 4: [OperationContract(Name = "AddDouble")] 5: double Add(double arg1, double arg2); 6: } My class implementing the ILearnWcfServiceExtend ends up as: 1: public class LearnWcfService : ILearnWcfServiceExtend 2: { 3: public int Add(int arg1, int arg2) 4: { 5: return arg1 + arg2; 6: } 7:  8: public double Add(double arg1, double arg2) 9: { 10: return arg1 + arg2; 11: } 12: } Now when I consume this service and look at the proxy that gets generated, here’s what I see: 1: public interface ILearnWcfServiceExtend 2: { 3: [System.ServiceModel.OperationContractAttribute(Action="http://tempuri.org/ILearnWcfService/AddInt", ReplyAction="http://tempuri.org/ILearnWcfService/AddIntResponse")] 4: int AddInt(int arg1, int arg2); 5: 6: [System.ServiceModel.OperationContractAttribute(Action="http://tempuri.org/ILearnWcfServiceExtend/AddDouble", ReplyAction="http://tempuri.org/ILearnWcfServiceExtend/AddDoubleResponse")] 7: double AddDouble(double arg1, double arg2); 8: } Only the ILearnWcfServiceExtend gets ‘listed’ in the proxy class and not the (base interface) ILearnWcfService interface. But then to uniquely identify the operations that the service exposes, the Action and ReplyAction properties are set. So in the above example, the AddInt operation has the Action property set to ‘http://tempuri.org/ILearnWcfService/AddInt’ and the AddDouble operation has the Action property of ‘http://tempuri.org/ILearnWcfServiceExtend/AddDouble’. Similarly the ReplyAction properties are set corresponding to the namespace that they’re declared in. The ‘http://tempuri.org’ is chosen as the default namespace, since the Namespace property on the ServiceContract is not defined. The other thing is the service contract itself – the Add() method. You’ll see that in both interfaces, the method names are the same. As you might know, this is not allowed in WSDL-based environments, even though the arguments are of different types. This is allowed only if the Name attribute of the ServiceContract is set (as done above). This causes a change in the name of the service contract itself in the proxy class. See that their names are changed to AddInt / AddDouble respectively. Lesson learned: The interface hierarchy gets ‘flattened’ when the WCF service proxy class gets generated.

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  • When would you put a semicolon after a method closing brace?

    - by froadie
    I've been programming in Java for a while, and I've just come across this syntax for the first time: public Object getSomething(){return something;}; What's interesting me is the final semicolon. It doesn't seem to be causing a compiler error, and as far as I know isn't generating runtime errors, so it seems to be valid syntax. When would I use this syntax? Or is it just something that is allowed but generally not used?

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  • iPhone multi-touch scale and rotate, how to prevent scale?

    - by russhill
    I have existing code for tracking multi-touch positions and then rotating and scaling the item - in this case an image - appropriately. The code works really well and in itself is perfect, however for this particular task, I need the rotation ONLY. I have spent time trying to work out what is going on in this routine, but maths is not my strong point so wanted to see if anyone could assist? - (CGAffineTransform)incrementalTransformWithTouches:(NSSet *)touches { NSArray *sortedTouches = [[touches allObjects] sortedArrayUsingSelector:@selector(compareAddress:)]; NSInteger numTouches = [sortedTouches count]; // No touches if (numTouches == 0) { return CGAffineTransformIdentity; } // Single touch if (numTouches == 1) { UITouch *touch = [sortedTouches objectAtIndex:0]; CGPoint beginPoint = *(CGPoint *)CFDictionaryGetValue(touchBeginPoints, touch); CGPoint currentPoint = [touch locationInView:self.superview]; return CGAffineTransformMakeTranslation(currentPoint.x - beginPoint.x, currentPoint.y - beginPoint.y); } // If two or more touches, go with the first two (sorted by address) UITouch *touch1 = [sortedTouches objectAtIndex:0]; UITouch *touch2 = [sortedTouches objectAtIndex:1]; CGPoint beginPoint1 = *(CGPoint *)CFDictionaryGetValue(touchBeginPoints, touch1); CGPoint currentPoint1 = [touch1 locationInView:self.superview]; CGPoint beginPoint2 = *(CGPoint *)CFDictionaryGetValue(touchBeginPoints, touch2); CGPoint currentPoint2 = [touch2 locationInView:self.superview]; double layerX = self.center.x; double layerY = self.center.y; double x1 = beginPoint1.x - layerX; double y1 = beginPoint1.y - layerY; double x2 = beginPoint2.x - layerX; double y2 = beginPoint2.y - layerY; double x3 = currentPoint1.x - layerX; double y3 = currentPoint1.y - layerY; double x4 = currentPoint2.x - layerX; double y4 = currentPoint2.y - layerY; // Solve the system: // [a b t1, -b a t2, 0 0 1] * [x1, y1, 1] = [x3, y3, 1] // [a b t1, -b a t2, 0 0 1] * [x2, y2, 1] = [x4, y4, 1] double D = (y1-y2)*(y1-y2) + (x1-x2)*(x1-x2); if (D < 0.1) { return CGAffineTransformMakeTranslation(x3-x1, y3-y1); } double a = (y1-y2)*(y3-y4) + (x1-x2)*(x3-x4); double b = (y1-y2)*(x3-x4) - (x1-x2)*(y3-y4); double tx = (y1*x2 - x1*y2)*(y4-y3) - (x1*x2 + y1*y2)*(x3+x4) + x3*(y2*y2 + x2*x2) + x4*(y1*y1 + x1*x1); double ty = (x1*x2 + y1*y2)*(-y4-y3) + (y1*x2 - x1*y2)*(x3-x4) + y3*(y2*y2 + x2*x2) + y4*(y1*y1 + x1*x1); return CGAffineTransformMake(a/D, -b/D, b/D, a/D, tx/D, ty/D); } I have tried to read up on the way matrix's work, but cannot figure it out entirely. More likely to be the issue is the calculations, which as I mention is not my strong point. What I need from this routine is a transform that performs my rotation but ignores scale - so the distance between the 2 finger touch points is ignored and scale is not affected. I have looked at other routines on the internet to handle multi-touch rotation but all the ones I tried had issues in some way or other, whereas the above code is spot on for scale and rotate actions. Any help appreciated!

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  • iPhone multi-touch move, scale and rotate, how to prevent scale?

    - by russhill
    I have existing code for tracking multi-touch positions and then moving, rotating and scaling the item - in this case an image - appropriately. The code works really well and in itself is perfect, however for this particular task, I need the movement and rotation ONLY. I have spent time trying to work out what is going on in this routine, but maths is not my strong point so wanted to see if anyone could assist? - (CGAffineTransform)incrementalTransformWithTouches:(NSSet *)touches { NSArray *sortedTouches = [[touches allObjects] sortedArrayUsingSelector:@selector(compareAddress:)]; NSInteger numTouches = [sortedTouches count]; // No touches if (numTouches == 0) { return CGAffineTransformIdentity; } // Single touch if (numTouches == 1) { UITouch *touch = [sortedTouches objectAtIndex:0]; CGPoint beginPoint = *(CGPoint *)CFDictionaryGetValue(touchBeginPoints, touch); CGPoint currentPoint = [touch locationInView:self.superview]; return CGAffineTransformMakeTranslation(currentPoint.x - beginPoint.x, currentPoint.y - beginPoint.y); } // If two or more touches, go with the first two (sorted by address) UITouch *touch1 = [sortedTouches objectAtIndex:0]; UITouch *touch2 = [sortedTouches objectAtIndex:1]; CGPoint beginPoint1 = *(CGPoint *)CFDictionaryGetValue(touchBeginPoints, touch1); CGPoint currentPoint1 = [touch1 locationInView:self.superview]; CGPoint beginPoint2 = *(CGPoint *)CFDictionaryGetValue(touchBeginPoints, touch2); CGPoint currentPoint2 = [touch2 locationInView:self.superview]; double layerX = self.center.x; double layerY = self.center.y; double x1 = beginPoint1.x - layerX; double y1 = beginPoint1.y - layerY; double x2 = beginPoint2.x - layerX; double y2 = beginPoint2.y - layerY; double x3 = currentPoint1.x - layerX; double y3 = currentPoint1.y - layerY; double x4 = currentPoint2.x - layerX; double y4 = currentPoint2.y - layerY; // Solve the system: // [a b t1, -b a t2, 0 0 1] * [x1, y1, 1] = [x3, y3, 1] // [a b t1, -b a t2, 0 0 1] * [x2, y2, 1] = [x4, y4, 1] double D = (y1-y2)*(y1-y2) + (x1-x2)*(x1-x2); if (D < 0.1) { return CGAffineTransformMakeTranslation(x3-x1, y3-y1); } double a = (y1-y2)*(y3-y4) + (x1-x2)*(x3-x4); double b = (y1-y2)*(x3-x4) - (x1-x2)*(y3-y4); double tx = (y1*x2 - x1*y2)*(y4-y3) - (x1*x2 + y1*y2)*(x3+x4) + x3*(y2*y2 + x2*x2) + x4*(y1*y1 + x1*x1); double ty = (x1*x2 + y1*y2)*(-y4-y3) + (y1*x2 - x1*y2)*(x3-x4) + y3*(y2*y2 + x2*x2) + y4*(y1*y1 + x1*x1); return CGAffineTransformMake(a/D, -b/D, b/D, a/D, tx/D, ty/D); } I have tried to read up on the way matrix's work, but cannot figure it out entirely. More likely to be the issue is the calculations, which as I mention is not my strong point. What I need from this routine is a transform that performs my movement and rotation but ignores scale - so the distance between the 2 finger touch points is ignored and scale is not affected. I have looked at other routines on the internet to handle multi-touch rotation but all the ones I tried had issues in some way or other (smoothness, jumping when lifting fingers etc), whereas the above code is spot on for move, scale and rotate actions. Any help appreciated!

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  • Vector of Object Pointers, general help and confusion

    - by Staypuft
    Have a homework assignment in which I'm supposed to create a vector of pointers to objects Later on down the load, I'll be using inheritance/polymorphism to extend the class to include fees for two-day delivery, next day air, etc. However, that is not my concern right now. The final goal of the current program is to just print out every object's content in the vector (name & address) and find it's shipping cost (weight*cost). My Trouble is not with the logic, I'm just confused on few points related to objects/pointers/vectors in general. But first my code. I basically cut out everything that does not mater right now, int main, will have user input, but right now I hard-coded two examples. #include <iostream> #include <string> #include <vector> using namespace std; class Package { public: Package(); //default constructor Package(string d_name, string d_add, string d_zip, string d_city, string d_state, double c, double w); double calculateCost(double, double); void Print(); ~Package(); private: string dest_name; string dest_address; string dest_zip; string dest_city; string dest_state; double weight; double cost; }; Package::Package() { cout<<"Constucting Package Object with default values: "<<endl; string dest_name=""; string dest_address=""; string dest_zip=""; string dest_city=""; string dest_state=""; double weight=0; double cost=0; } Package::Package(string d_name, string d_add, string d_zip, string d_city, string d_state, string r_name, string r_add, string r_zip, string r_city, string r_state, double w, double c){ cout<<"Constucting Package Object with user defined values: "<<endl; string dest_name=d_name; string dest_address=d_add; string dest_zip=d_zip; string dest_city=d_city; string dest_state=d_state; double weight=w; double cost=c; } Package::~Package() { cout<<"Deconstructing Package Object!"<<endl; delete Package; } double Package::calculateCost(double x, double y){ return x+y; } int main(){ double cost=0; vector<Package*> shipment; cout<<"Enter Shipping Cost: "<<endl; cin>>cost; shipment.push_back(new Package("tom r","123 thunder road", "90210", "Red Bank", "NJ", cost, 10.5)); shipment.push_back(new Package ("Harry Potter","10 Madison Avenue", "55555", "New York", "NY", cost, 32.3)); return 0; } So my questions are: I'm told I have to use a vector of Object Pointers, not Objects. Why? My assignment calls for it specifically, but I'm also told it won't work otherwise. Where should I be creating this vector? Should it be part of my Package Class? How do I go about adding objects into it then? Do I need a copy constructor? Why? What's the proper way to deconstruct my vector of object pointers? Any help would be appreciated. I've searched for a lot of related articles on here and I realize that my program will have memory leaks. Using one of the specialized ptrs from boost:: will not be available for me to use. Right now, I'm more concerned with getting the foundation of my program built. That way I can actually get down to the functionality I need to create. Thanks.

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  • Parsing scripts that use curly braces

    - by Keikoku
    To get an idea of what I'm doing, I am writing a python parser that will parse directx .x text files. The problem I have deals with how the files are formatted. Although I'm writing it in python, I'm looking for general algorithms for dealing with this sort of parsing. .x files define data using templates. The format of a template is template_name { [some_data] } The goal I have is to parse the file line-by-line and whenever I come across a template, I will deal with it accordingly. My initial approach was to check if a line contains an opening or closing brace. If it's an open brace, then I will check what the template name is. Now the catch here is that the open brace doesn't have to occur on the same line as the template name. It could just as well be template_name { [some_data] } So if I were to use my "open brace exists" criteria, it won't work for any files that use the latter format. A lot of languages also use curly braces (though I'm not sure when people would be parsing the scripts themselves), so I was wondering if anyone knows how to accurately get the template name (or in some other languages, it could just as well be a function name, though there aren't any keywords to look for)

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  • Is it possible for double-escaping to cause harm to the DB?

    - by waiwai933
    If I accidentally double escape a string, can the DB be harmed? For the purposes of this question, let's say I'm not using parametrized queries For example, let's say I get the following input: bob's bike And I escape that: bob\'s bike But my code is horrible, and escapes it again: bob\\\'s bike Now, if I insert that into a DB, the value in the DB will be bob\'s bike Which, while is not what I want, won't harm the DB. Is it possible for any input that's double escaped to do something malicious to the DB assuming that I take all other necessary security precautions?

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