variables

问题 I use Gnuplot and I would like to save values of a datafile into a variable with condition. For example, I have the following datafile 'example.dat': columnl column2 5 7.0 3 4.0 7 6.0 In my gnuplot script, I would like to be able to write: variable = " in the file 'example.dat' ($1)==5 ? $2 : 1/0 " which would be here the same as: variable = 7.0 of course the value depends on the datafile. So is it possible? If not, is it possible without condition? 回答1: This is how I worked around the

问题 I am struggling to understand Variables Shadowed Methods Overriden Concept of inheritance with Java. Case 1: class Car{ public int gearRatio = 8; public String accelerate() { return "Accelerate : Car"; } } class SportsCar extends Car{ public int gearRatio = 9; public String accelerate() { return "Accelerate : SportsCar"; } public static void main(String[] args){ Car c = new SportsCar(); System.out.println( c.gearRatio+" "+c.accelerate() ); } } Output: 8 Accelerate : Sportscar. Case 2: public

问题 I am new to Ruby and currently trying a few examples from the Ruby book I am using as a guide: class Account attr_accessor :balance def initialize(balance) @balance = balance end end class Transaction def initialize(account_a, account_b) @account_a = account_a @account_b = account_b end def debit(account,amount) account.balance -= amount end def credit(account,amount) account.balance += amount end def transfer(amount) debit(@account_a, amount) credit(@account_b, amount) end end savings =

问题 It's the first time I use OOP with PHP 5.. so this is my problem.. I have a file disp.php that contains a class named class disp (model in MVC) <?php class disp{ public $n_pages; public $current_page; private $cmd2; /***************SQL command generator*******************/ private function getCmd2($cmd1,$id,$first_entry,$perpage,$tri){ $cmd2=str_replace('COUNT(*)','*',$cmd1); $cmd2=$cmd2.' ORDER BY '.$id.' '.$tri.' LIMIT '.$first_entry.','.$perpage; return $cmd2; } /********************Items

问题 I'm happy a bit of a variable scoping problem. Maybe I just need more coffee... Here's my (simplified) code - this is in CodeIgniter 2: class Agent extends CI_Controller { public function __construct() { parent::__construct(); $this->load->model('agent_model'); // Get preliminary data that will be often-used in Agent functions $user = $this->my_auth_library->get_user(); $agent = $this->agent_model->get_agent($user->id); } public function index() { $this->template->set('info', $this->agent

问题 I use the following in my C++ code: int a = 0, b = a; I would like to know if this behaviour is reliable and well defined (left to right order of name declaration) and that my code will not break with other compilers with an undeclared name error. If not reliable, I would break the statement: int a = 0; int b = a; Thank you. 回答1: I believe the answer is no. It is subject to core active issue 1342 which says: It is not clear what, if anything, in the existing specification requires that the

问题 I use the following in my C++ code: int a = 0, b = a; I would like to know if this behaviour is reliable and well defined (left to right order of name declaration) and that my code will not break with other compilers with an undeclared name error. If not reliable, I would break the statement: int a = 0; int b = a; Thank you. 回答1: I believe the answer is no. It is subject to core active issue 1342 which says: It is not clear what, if anything, in the existing specification requires that the

问题 I have looked for some responses on the web, but none of them are very accurate. I want to be able to do this: $id = "" . $result ["id"] . ""; $info = array('$id','Example'); echo $info[0]; Is this possible in any way? 回答1: What you need is (not recommended): $info = array("$id",'Example'); // variable interpolation happens in "" or just $info = array($id,'Example'); // directly use the variable, no quotes needed You've enclosed the variable inside single quotes and inside single quotes

问题 In javascript I have a variable that I push to console.log then increment it and push it to the log again, which shows the below in the Chrome Dev Tools. This variable has done some freaky stuff, like if I try to use the += operator to add to it, it actually puts the added value after the number (for example if x=5 and I did x+=3 , x would equal 53 ). The really boggling part of this is that incrementing it with ++ works as expected, but my question isn't why that's happening but rather why

问题 We are using Tesseract OCR Java library called Tess4J. It works fine if run as a standalone application. It needs a variable called TESSDATA_PREFIX which contains the tessdata config and other charset related files. It also runs fine with embedded Tomcat 6 server in eclipse. I had set TESSDATA_PREFIX as an environment variable by using the launch configuration. But when I package everything into a WAR and drop it in deploy directory of tomcat, the environment variable does not seem to be