I am trying to create a basic banking system to practice using classes, after creating the parent class "Account", I tried to create a "savings" class which will be the child class and inherit the attributes and methods, however, no matter what I look up nothing will tell me how to do this. I get errors such as "must declare a body because it is not marked abstract, extern or partial", and so on. I really don't know what to do to get it working, so I'm hoping someone here can help, here's my code:  public class Account {     protected string name;     protected string birthdate;     protected string address;     protected double balance;     protected string status;     protected string type;      public Account(string customerName, string customerBirthdate, string customerAddress, int customerBalance)     {         name = customerName;         birthdate = customerBirthdate;         address = customerAddress;         balance = customerBalance;         status = "Ok";         type = "Basic";              }      public void customerDetails()     {         Console.WriteLine("Name: {0}, Birthdate: {1}, Address: {2}", name, birthdate, address);     }      public void accountDetails()     {         Console.WriteLine("Balance: £{0}, Account Status: {1}, Account Type: {2}", Math.Round(balance, 2), status, type);     }      private void updateStatus()     {         if (balance &lt; 0)         {             status = "Overdrawn";         }         else if (balance &gt; 0 )         {             status = "Ok";         }     }      public void deposit(int amount)     {         balance += amount;         updateStatus();     }      public void withdraw(int amount)     {         balance -= amount;         updateStatus();     } }  public class Savings : Account {     public Savings(string customerName, string customerBirthdate, string customerAddress, int customerBalance) : Account(customerName, customerBirthdate, customerAddress, customerBalance)     {         name = customerName;         birthdate = customerBirthdate;         address = customerAddress;         balance = customerBalance;         status = "Ok";         type = "Basic";     } }   Thanks in advance if anyone can help me out!
If I inherit from a base class and want to pass something from the constructor of the inherited class to the constructor of the base class, how do I do that?  For example, if I inherit from the Exception class I want to do something like this:  class MyExceptionClass : Exception {      public MyExceptionClass(string message, string extraInfo)      {          //This is where it's all falling apart          base(message);      } }   Basically what I want is to be able to pass the string message to the base Exception class.
Misplaced Accents in Cyrillic Text In educational material for the Russian language and linguistic literature the need to put accents on Cyrillic vowels often arises. However when I tried to do this with luaLaTeX the accents where misplaced.  \documentclass[11pt]{article} \usepackage[utf8]{inputenc} \usepackage{fontspec} \setmainfont{Linux Libertine:style=Regular} \begin{document}  Е́сли вы изу́чите  \'{Е}сли вы из\'{у}чите  \'{E}сли вы из\'{y}чите % Here "E" and "y" are Latin glyphs, but this workaround does not                         % work with all Cyrillic letters e.g. Я, Ю \end{document}     The last line would looks nice, but unfortunately these are Latin glyphs.  Is this a problem with the font used (Linux Libertine) or with LaTeX? Photoshop resize circularly Number of labeled trees which have one vertex of degree 4 How many labeled trees which have one vertex of degree 4 can we have? A tree with $10$ vertices has $9$ edges, so the sum of the degrees of the vertices is $2\cdot 9=18$. If there is one vertex of degree $4$, the sum of the degrees of the other $9$ vertices must be $14$. I don't know what to do next. Should I count all possible vertex degrees? I have taken three fields from case object called AccountName, IntegrationTo__c and SfType__c (checkbox).  I have created one case record with a specific combination of three fields.  For the second time I create a record with that combination, then  display error message only if SfType__c is true in first record otherwise allow  for record creation.  trigger AvoidDuplicate on Case(before insert)  {          set&lt;string&gt; newNameSet = new set&lt;string&gt;();     newNameSet = new set&lt;string&gt;();      set&lt;string&gt; newEmailSet = new set&lt;string&gt;();      set&lt;string&gt; dbNameSet = new set&lt;string&gt;();      set&lt;string&gt; dbEmailSet = new set&lt;string&gt;();      for(Case newLead : trigger.new){          newNameSet.add(newLead.Account.Name);          newEmailSet.add(newLead.IntegrationTo__c);      }      for(Case dbLead : [select id, Case.Account.Name, IntegrationTo__c from Case where IntegrationTo__c IN: newEmailSet OR Case.Account.Name IN: newNameSet]){          dbNameSet.add(dbLead.Account.Name);          dbEmailSet.add(dbLead.IntegrationTo__c);      }      for(Case newLead : trigger.new){          if(dbNameSet.contains(newLead.Account.Name) &amp;&amp; dbEmailSet.Contains(newLead.IntegrationTo__c))              newLead.addError('You are inserting Duplicate Case');      }  }   i wrote this this not checking the account field name and integration__c values only with combination of account and integration__c shows error Solve $y'-\int_0^xy(t)dt=2$ I have not idea how to approach this differential equation.   $$y'-\int_0^xy(t)dt=2$$.  Basically, I did,  $$F''(t)-F(x)+F(0)=2 \;\;\;\;\;\;\; F'=y$$  I am stuck.  Thank You. The problem is stated as follows:  "Let $R$ be a Noetherian ring and $\theta$ be a ring homomorphism from $R$ to $R$. Show that if $\theta$ is surjective then it is also injective."  Regardless of the right solution, I don't understand why is the following wrong:     We have $\theta: R\to R$. By the isomorphism theorem $R/\ker\theta\cong\operatorname{Im}\theta$. Since $\operatorname{Im}\theta = R$, it follows $\ker\theta =0$, so it's injective.   Harsh criticism will be appreciated. Thanks. Help us test the alpha version of our Android app We are in the early stages of development of the official Stack Exchange Android app and we need your help with testing. To set a few expectations: there will be bugs, crashes, and missing features, all of which will be fixed in .    We are initially targeting Android devices running  (Android 4.1 or higher) starting with phones (up to ~5 inch) and eventually moving our way to tablets.    To register for alpha testing .  After you register we will send you an invite to a private Google community where you can find a link to download our app directly from the  store. The invitations will be sent out in waves, so if you don’t get an invite immediately, be patient.  Crash reports will be automatically reported back to us using . Bugs or feature requests should be reported here on meta and tagged . Please do not use the Google community to report bugs.  As always, we welcome your feedback and are committed to building the best mobile app possible for browsing the Stack Exchange sites. Best practices with STDIN in Ruby? I want to deal with the command line input in Ruby:  &gt; cat input.txt | myprog.rb &gt; myprog.rb &lt; input.txt &gt; myprog.rb arg1 arg2 arg3 ...   What is the best way to do it? In particular I want to deal with blank STDIN, and I hope for an elegant solution.  #!/usr/bin/env ruby  STDIN.read.split("\n").each do |a|    puts a end  ARGV.each do |b|     puts b end Consider an isosceles triangle. Let r be the radius of the circumscribed circle and p be the radius of the inscribed circle. Prove that the distance d between the centers of these two circles is $$d = \sqrt{r(2p-r)}$$ Margin of caption different than text body in 2-column table (cas-dc) $\exp(A)$ is orthogonal iff $A$ is skew symmetric Let $A \in M_n(\mathbb R)$ and $\exp(A)=\sum_{i=0}^{\infty}\frac{A^i}{i!}$. How to prove $\exp(A)$ is an orthogonal matrix iff $A^t=-A$?  I can get that $\exp(A)$ is an orthogonal matrix iff $\exp(A^t)=\exp(-A)$, but how to get $A^t=-A$ from it?  What's more, is $\exp(A)$ injective or not? How to make a multiboot CD that will start a user-chosen ISO file I have many CD ISOs downloaded from the Internet. They are each about 100 MB in size and consist of repair/diagnostic programs and other tools. Some of them are Linux-based; others are based on DOS clones, like FreeDOS. I want to put all of the ISOs onto one bootable DVD, so that when I use the DVD, I will get a menu prompting me to select the ISO I want to boot. How can I do this? I've seen some rescue CDs that are combinations of other people's ISOs, but I have no idea how they were made.  Regarding bounty: I, a different person than the OP, have placed a bounty on this question for a solution that meets ALL of these criteria:  Is for DVDs (not flash drives!!!) Is free Works with any ISO file, regardless of original OS What can cause "Android OS" process to use high percentage of battery? I used to think that all users can delete their own posts, as long as these posts haven't gained a relevant number of upvotes. After seeing posts  again and again, I decided to verify my assumption and found out that you actually can't delete your own answers if you post from a low reputation, cookie based account.  Is there a reason for this or is this unintentional?  In my opinion even users without a "substantial" account should be able to change their minds and delete an answer if they think better of it. I wanted to know which php version I am using so I wrote the standard script:   phpinfo();   Which gives me  PHP version 5.6.10   The correct PHP version needed for my application. When I tried in terminal:  php -i   or  php -v   It shows me:  PHP version 5.3.2   Which I don’t need. Then I tried with:  which php   It shows me:  /usr/bin/php   Now I am confused which version of PHP I am using. The files are uploaded to the hosting website and I cannot make any changes to the config files like httpd.conf or php.ini. Question is about Ubuntu release process. Are migrations from n to n+1 releases expected?  Assuming we have server with installed Ubuntu 14.04 LTS. Will it be smoothly upgradable to Ubuntu 16.04 LTS via apt-get upgrade ?  Assumptions:   scope is software therefore we assume that given hardware is supported on both releases (upgrading from and to) that's why, always before upgrade you are asked to make backup to be able to revert in case of failure It is given in a question that $\vec x+\vec a=(\vec a\cdot \vec x)\vec b$ and it is stated that $\vec a$, $\vec b$ and $\vec x$ are vectors.  It is also stated that $\vec a\cdot \vec b\ne 1$.  The question asks to express $\vec x$ in term $\vec a$ and $\vec b$.  How do you this? Performance of Non Clustered Indexes on Heaps vs Clustered Indexes compares the performance for individual select/insert/delete/update and range select statements on a table organized as a clustered index vs that on a table organized as a heap with a non clustered index on the same key columns as the CI table.  Generally the clustered index option performed better in the tests as there is only one structure to maintain and because there is no need for bookmark lookups.  One potentially interesting case not covered by the paper would have been a comparison between a non clustered index on a heap vs a non clustered index on a clustered index. In that instance I would have expected the heap might even perform better as once at the NCI leaf level SQL Server has a RID to follow directly rather than needing to traverse the clustered index.   Is anyone aware of similar formal testing that has been carried out in this area and if so what were the results? Lifting idempotents modulo a nilpotent ideal I'm bugged by the following that's summarized on p. 109 of .     False theorem: All horses are the same color.      Proof by induction:      $\fbox{$P(n)$ is the statement: In every set of horses of size $n$, all $n$ horses are the same color.}$   $\fbox{Base Case or $P(1)$:}$ One horse is the same color as itself. This is true by inspection.   $\fbox{Induction Step:}$ Assume $P(k)$ for some $k \geq 1$.   $\fbox{Proof of $P(k + 1) :$}$   Since $\{H_1, H_2, ... , H_n\}$ is a set of $n$ horses, the induction hypothesis applies to this set. Thus, all the horses in this set are the same color.   Since $\{H_2, H_3, ... , H_{n+1}\}$ is also a set of $n$ horses, the induction step likewise holds for this set. Thus, all the horses in this set are the same color too.         Therefore, all $n +1$ horses in $\{H_1, H_2, H_3, ... , H_n , H_{n+1}\}$ are the same color. QED.   The issue the instructor was trying to point out is clearly valid. For the case $n = 1$, there is only ${H_1}$. So this case says nothing about possible overlapping elements of each set of $(n + 1)$, for instance $H_2$ in the above proof.    But it was proposed in the class discussion that this was the only problem. Had you been able to prove $P(2)$ true, then a proof of the above format would have been fine.    My interpretation is that yes, you could prove all horses are the same color, if you can prove that any set of two horses will be the same color. But this format would not work.  Why not? The problem I see is that the above proof is for the existence of at least one particular pair of sets of horses of sizes $n$ and $n + 1$, such that in each set, all horses are the same color.  Particularly when the set of size $n$ is a subset of the set of size $n + 1$.  In order to prove the induction step, don't you need to prove that sets of sizes $n$ and $n + 1$, do not necessarily contain the same, overlapping elements?  You could prove that any horse can be added to a set of 2 horses.  Take the last two, and they must be the same color, and so on.  Wwhatever color the first two happen to be, all other horses must thus be the same color.    Am I misinterpreting the example, or am I making a logical error? Thanks in advance.