C++ :: Inherit From Cout - How To Override Operator And Forward To Base
May 8, 2012
Using c++11, but I don't think that matters here.
output.displayHeader() must execute before the inherited from ostream (cout) executes streaming data, or bad things happen. It's of course not as simple as in the example below, and I need to make sure displayHeader() is never missed.
I'm thinking I need to override the "<<" operator, having my own function call displayHeader(), then call the base (cout) "<<" operator. What's the proper syntax for doing this?
I can't call displayHeader() in the constructor, and I can't call it right after the object is defined. There are exception case scenarios where displayHeader() must not be called, and other things must happen instead.
I'm aware this will result in many redundant bool comparisons versus the way I'm doing it now, and I'm perfectly OK with that.
Code:
#include <iostream>
using namespace std;
class myOutput : public ostream {
public:
myOutput() : ostream(cout.rdbuf()) {
// Creating and joining string objects #include <iostream> #include <string> using std::cin; using std::cout; using std::endl; using std::string; using std::getline; // List names and ages void listnames(string names[], string ages[], size_t count) {
[Code] ....
I may be wrong, but the problem seems to be in the function "listnames". Specifically, the output statement inside the while loop. I don't understand , how the ++ operator is behaving in this statement. The output produced does not match what's printed in the book. I usually just type all the examples, but with this one I also downloaded the source code from the book's website to make sure the error wasn't due to mistyping.
I just wanted to add strings in any base form (example 1101+100 = 10001 in base-2 but it could be added using any base-form like in base-3 to base-36) and I'm having a big trouble with my code because it gave me incorrect results.
addition(char st[], char st2[], int base){ int i, j, carry = 0, ans, len, o=0, z=1, l=0; char final[50]; if(strlen(st)>=strlen(st2)) len = strlen(st); else len = strlen(st2);
I am trying to inherit from class but the same error is appearing
Code: 1>c:userskthdu_000documentsvisual studio 2010projects ectangle ectangle1crectangle.h(1): error C2011: 'Crectangle' : 'class' type redefinition the following is my classes crectangle.h
Code: #include <iostream> #include <string> using namespace std; class test{ public: virtual void ola() {
[Code] .....
Like you see, i don't re-declare the 'ola' function in 'test1' class, only in 'test' class. The compiler tell me the 'ola' isn't member of 'test1'. in 'test' i put it 'virtual', but forgetting that, how can i override it without re-declare it?
I need to override a few methods in FILE class so i defined few methods as
EnCrpt * fp; fp * fopen(const char * filename, const char * mode); int fwrite(const void * p,int length,int readLenth,FILE * fpp = NULL); int fread(void * p,int length,int readLenth,FILE * fpp = NULL); int fseek(FILE * fpp = NULL,long offset, int whence); long ftell(FILE * fpp = NULL); int feof(FILE * fpp = NULL); int fflush(FILE * fpp = NULL); int fclose(FILE * fpp = NULL);
I will call fread method in my encrypted file class .. similar to other methods.. is this correct ? can NULL file pointer create issue ?
Because i have so many place where FILE class called i don't want to change everywhere to call encrypted file class so i am override these methods to encrypted file class instead of standrd FILE class
How would I go about shrink the duplicate data set from CWorksheetTwo? For CWorksheetTwo has both CUser and CUserEx, and I only need CUserEx, and all other classes are happy with CUser
Since there is no such thing virtual variable what are my choices? In CWorksheetTwo set users to NULL and use another exclusively? Change CSettings variable to template <class T> std::vector<T>users?
A quick clarification on virtual methods after reading Jumping int C++ by Alex Allain. If a user wanted to extend a class from someone elses library and override its methods that do not contain virtual methods; how would one call the overridden class if it is referred to by its super type
in other words how would someone override a method from someone elses library that does not have virtual keywords.
I'm overriding OnNcPaint to do my own caption painting (in a dialog box). If I call "Default" before I do my painting, the default caption and borders remain (as if I'm not painting at all). If I comment out my call to "Default", my caption looks great, but I get no menu bar (I have a menu on the dialog). If I call "DrawMenu" before or after painting, the dialog is all screwed up (and there is no painting in the nonclient area).
I got this algorithm of conversion and now I'm stuck at how to code it.
"Algorithm to Convert From any Base to Base 10 Decimal."
Let 'n' be the number of digits in the number. For example, 104 has 3 digits, so 'n'=3. Let 'b' be the base of the number. For example, 104 is decimal so 'b' = 10. Let 's' be a running total, initially 0.
For each digit in the number, working left to right do:
Subtract 1 from 'n'. Multiply the digit times b^n and add it to 's'.
When done with all the digits in the number, the decimal value should be 's' .
I need to convert an integer, for example 10, to its base 16 equivalent, 16. I found this code that converts a base 16 number to base 10, but I need the opposite. Plus, this code doesn't seem to work properly with input values under 32.
I'm doing a refresher for C++ and have gotten to operator overloading. I'm trying to perform an operator overload with the insertion (<<) operator, but I have encountered a problem.
Here's my class [In a header file "Shinigami.h"]
#include<string> namespace K{ class Quincy; class Shinigami{ friend std::ostream& operator<<(std::ostream&, const Shinigami&);
[Code] .....
If the operator function is a friend of the 'Shinigami' class, why doesn't it recognize any of it's private members? I need it to be in this file because I'm doing a bit of association with the 'Quincy' class.
I thought it was the namespace, but I included that.
error C2371: '`anonymous-namespace'::geometry::Point' : redefinition; different basic types 1> e:..........NavigationMesh.h(10) : see declaration of '`anonymous-namespace'::geometry::Point'
What can I do to forward declare external classes like this?
I have a class "SelectionGroup" which derives from a class "RMFObjectContainer". RMFObjectContainer has member variables of type SelectionGroup, so I need to include SelectionGroup.h in the header of RMFObjectContainer.h.
However, since SelectionGroup needs RMFObjectContainer to derive from it, I get a typical case of mutual inclusion.
I then proceeded to put the forward declaration class RMFObjectContainer; instead of #include "RMFObjectContainer.h" into the header of SelectionGroup.h.
However, I receive the following compile error (MSVC2010), as if the forward declaration was unseen:
#pragma once #include "Solid.h" #include "Entity.h" #include "SelectionGroup.h"
Code: class SomeOtherClass; void foo(SomeOtherClass* p);
And
Code: void foo(class SomeOtherClass* p);
I was told that "2" would limit the scope of the forward declaration to the declaration of foo... However, after testing it, it appears that both behave the same...
I am making a calendar to look similar to Outlook, but it is in c++ and I am starting from scratch. I have broken it into parts, and the part I am struggling with is making the next/previous month button to add to the calendar. I have a basic code, but I don't know exactly what I need to change or add to it. The code is,
#include "std_facilities_lib_3.h" #include <iostream> #include <sstream> #include "Graph.h" // get access to our graphics library facilities #include "GUI.h" #include "Window.h"
i hit the point where i have two class templates that are dependent on each other (in detail, class a stores a pointer of class b), creating a cyclic include issue.
Usually i resolve this with a forward declaration, but i cant seem to figure out how to do it with a template class.In fact, ( i think) i got it to work for this :
Code: template<typename T> class a { public: T x; }
but not for this:
Code: template<int b> class b { public: int getb(){return b;} }
I have a header file in which we include vector at the top. But we want to remove that include. On doing so I get compilation errors as the header file uses std::vector<> at several instances in header file so I have to forward declare the vector to solve this issue.how i can do it.
I am trying to compile the files below. The PosLin.cpp contains the SurTriAuto and SurTriPosRotAndQ functions below. Before adding SurTriPosRotAndQ, it compiled fine, but when I added SurTriPosRotAndQ, I am getting "invalid use of incomplete type ‘struct PosRotAndQ" error messages
I was thinking I could try moving SurTriAuto and SurTriPosRotAndQ to PosLin.h, but since they return "T*", I'm not sure what to do
I have a "t.h" file
namespace TNS { class T {
[Code]....
when I add "include Pos/PL.h" to geopar.h, I get an error saying v.hpp is missing, where v.hpp is part of a 3rd-party software and it is already in my directory
