Interview Questions Answers.ORG
Interviewer And Interviewee Guide
Interviews
Quizzes
Home
Quizzes
Interviews Databases Programming Interviews:BtrieveClipperData ModelingData StructuresDatabase AdministrationDatabase Administrator (DBA)Database AnalystDatabase DeveloperDB DevelopmentEDI/Data Integration ExpertFirebirdHierarchicalIBM DB2InformixJava DatabaseMariaDBMicrosoft Access DeveloperMongoDBMS SQL ServerMySQL ProgrammingNetworkNoSQLObject RelationalPostgrePostgreSQLProgressRDBMSRelationalSQLSQL AdministratorSQL and PL/SQLSQL Notification ServicesSQL server 2008SSRSStored ProcedureSybaseTeradata
Copyright © 2018. All Rights Reserved
Data Structures Interview Question:
What is placement new in data structures?
Submitted by: AdministratorWhen you want to call a constructor directly, you use the placement new. Sometimes you have some raw memory that's already been allocated, and you need to construct an object in the memory you have. Operator new's special version placement new allows you to do it.
class Widget
{
public :
Widget(int widgetsize);
…
Widget* Construct_widget_int_buffer(void *buffer,int widgetsize)
{
return new(buffer) Widget(widgetsize);
}
};
This function returns a pointer to a Widget object that's constructed within the buffer passed to the function. Such a function might be useful for applications using shared memory or memory-mapped I/O, because objects in such applications must be placed at specific addresses or in memory allocated by special routines.
Submitted by: Administrator
class Widget
{
public :
Widget(int widgetsize);
…
Widget* Construct_widget_int_buffer(void *buffer,int widgetsize)
{
return new(buffer) Widget(widgetsize);
}
};
This function returns a pointer to a Widget object that's constructed within the buffer passed to the function. Such a function might be useful for applications using shared memory or memory-mapped I/O, because objects in such applications must be placed at specific addresses or in memory allocated by special routines.
Submitted by: Administrator
Copyright 2007-2024 by Interview Questions Answers .ORG All Rights Reserved.
https://InterviewQuestionsAnswers.ORG.
https://InterviewQuestionsAnswers.ORG.