c++ - How can I add and initialize objects in a vector without having the destructor for the existing objects called? -

-

i working homework assignment , have come across problem when added destructor class.

from assignment:

the class have destructor displays message indicating object has "gone out of scope".

i've implemented in rectangle class outputting ofstream object:

rectangle::~rectangle() {     rectoutput << "object length " << length << " , width " << width << " out of scope." << std::endl; }

the problem i'm running that, put these objects vector make easy output table. looked until added destructor. due way vectors copy data new internal array , delete old array increase size, destructor called , message output several times in creation of objects.

part of constraints of homework had initialize of objects values. choice use vector own. here code of initalization of objects: 

std::vector <rectangle> rectangles;  //initialize of our rectangle objects within our vector rectangles.push_back(rectangle()); rectangles.push_back(rectangle(7.1, 3.2)); rectangles.push_back(rectangle(6.3)); rectangles.push_back(rectangle(21.0, 21.0)); rectangles.push_back(rectangle(rectangles[1]));

and here output being produced this:

object length 1 , width 1 out of scope.
object length 1 , width 1 out of scope.
object length 7.1 , width 3.2 out of scope.
object length 1 , width 1 out of scope.
object length 7.1 , width 3.2 out of scope.
object length 6.3 , width 1 out of scope.
value of 21 invalid. values must greater 0.0 , less or equal 20.0. default of 1.0 used.
value of 21 invalid. values must greater 0.0 , less or equal 20.0. default of 1.0 used.
object length 1 , width 1 out of scope.
object length 7.1 , width 3.2 out of scope.
object length 6.3 , width 1 out of scope.
object length 1 , width 1 out of scope.
object length 1 , width 1 out of scope.
object length 7.1 , width 3.2 out of scope.
object length 6.3 , width 1 out of scope.
object length 1 , width 1 out of scope.
object length 7.1 , width 3.2 out of scope.

how can initialize these objects in vector without having destructor being called repeatedly this? tried start off std::vector <rectangle> rectangles(5);, seems call default constructor 5 times, filling vector 5 default rectangle objects , when add same effect seen, except destructing default objects.

use rectangles.emplace_back() instead of rectangles.push_back() , still need reserve mentioned sam varshavchik


Comments

Post a Comment

Popular posts from this blog

java - Run spring boot application error: Cannot instantiate interface org.springframework.context.ApplicationListener -

-
i have spring project , try make use spring boot , run @ embadded tomcat following : https://spring.io/guides/gs/rest-service/ this application //@configuration //@enableaspectjautoproxy @springbootapplication @componentscan(basepackages = "gux.prome") public class application { public static void main(string[] args) { springapplication.run(application.class, args); } } if use maven command: mvn spring-boot:run , project starts fine, need debug , run main method @ intelij, exception occurs: exception in thread "main" java.lang.illegalargumentexception: cannot instantiate interface org.springframework.context.applicationlistener : org.springframework.boot.logging.classpathloggingapplicationlistener @ org.springframework.boot.springapplication.createspringfactoriesinstances(springapplication.java:414) @ org.springframework.boot.springapplication.getspringfactoriesinstances(springapplication.java:394) @ org.springframework.bo...
Read more

reactjs - React router and this.props.children - how to pass state to this.props.children -

-
i'm using react-router first time , don't know how think in yet. here's how i'm loading components in nested routes. entry point .js reactdom.render( <router history={hashhistory} > <route path="/" component={app}> <route path="models" component={content}> </route> </router>, document.getelementbyid('app') ); app.js render: function() { return ( <div> <header /> {this.props.children} </div> ); } so child of app content component sent in. i'm using flux , app.js has state , listens changes, don't know how pass state down this.props.children. before using react-router app.js defines children explicitly, passing state natural don't see how now. using couple of react helper methods can add state, props , whatever else this.props.children render: function() { var children = react.ch...
Read more

Excel VBA "Microsoft Windows Common Controls 6.0 (SP6)" Location Changes -

-
i have excel workbook used generate quotations customers. there main page user inputs data, , there buttons generate various pdfs , send them customer. however, 1 user consistently getting error preventing generating , sending pdfs. i beleive "microsoft windows common controls 6.0 (sp6)". it's installed on users' computers. on mine, location "c:\windows\syswow64\mscomctl.ocx" on others "c:\windows\system32\mscomctl.ocx" the user experiencing issues on 32-bit machine, "mscomctl.ocx" file should in system32. have manually put in there, , pointed common controls reference in vba it. issue seems keep reverting looking in syswow64. since folder doesn't exist, can't find it, , can't produce pdfs. i thought perhaps issue user running older version of office (2007) there users on 2013 , 2016. thought perhaps mixture of 64-bit , 32-bit users. user gets sent workbook other users (as quotation process goes further, gets passed ...
Read more