Suppose i have a function:
int & f1(int & p) {
return p;
}
void main() {
int a,b;
b = 10;
a = f1(b);
a = 11;
cout<<b<<endl;
}
why when i change a, b doesnt change? a is supposed to be an alias of b right?
From the page: [URL] ....
#include <iostream>
using namespace std;
int n;
int& test();
[Code] ....
Explanation
In program above, the return type of function test() is int&. Hence this function returns by reference. The return statement is return n; but unlike return by value. This statement doesn't return value of n, instead it returns variable n itself.
Then the variable n is assigned to the left side of code test() = 5; and value of n is displayed.
I don't quite understand the bold sentence. Shouldn't value of n and variable n be the same?
While working on another issue I started memory cleaning and refactoring. While refactoring I decided to create an array Resize Array Reize and Null Count:
Spoiler
public int NullCount(string[,] Original) {
try {
int returnInt =0;
for(int x =0; x<= Original.GetUpperBound(0);x++) {
if (Original[x,0]==null )
{returnInt++;}
[code]......
I am having trouble compiling my interface. I am trying to store a reference variable as a member variable of the interface object. Compiler says that the variable has not be initiated correctly.
LCD inherits from VisualInterface which is expecting a DisplayDriver object to be passed in (DisplayDriver is another interface, but thats not important).
I pass the displayDriver object in when LCD is instantiated in maininterfaces.zip
I was pasing it before as a pointer but was told that this could cause me problems with memory leaks and a reference was better, but now I cant seem to get it to compile.
I have code here that uses assignment operators that doesn't return by reference and it still works. So why does my book say you need to return by reference?
Here is a quote from my book:
The return type of operator= is a reference to the invoking object, so as to allow chained
assignments a=b=c.
The code below is from my book. I simply removed '&', in the original code that has assignment operators return by reference, from IntCell & operator=. This way the assignment operator no longer returns a reference, and it still works.
#include <iostream>
using namespace std;
class IntCell {
public:
explicit IntCell( int initialValue = 0 )
{ storedValue = new int{ initialValue }; }
[Code] .....
I dont know what kind of return reference I have to put to override the following derived member function in C++:
virtual SEntityPhysicalizeParams& GetPhysicsParams() override {return ???;}
The place where I should put the return value is marked with ???. SEntityPhysicalizeParams is a struct from another header from which I dont have access to it's source file.
I tried several things but noone seemed to work out and keep getting me either error "function must return a value" or "initial value of reference to non-const must be an lValue".
Here is SEntityPhysicalize where my function is refering to:
struct SEntityPhysicalizeParams
{///////////////////////////////////////////////////////////////////
SEntityPhysicalizeParams() : type(0),density(-1),mass(-1),nSlot(-1),nFlagsOR(0),nFlagsAND(UINT_MAX),
pAttachToEntity(NULL),nAttachToPart(-1),fStiffnessScale(0), bCopyJointVelocities(false),
pParticle(NULL),pBuoyancy(NULL),pPlayerDimensions(NULL),pPlayerDynamics(NULL),
pCar(NULL),pAreaDef(NULL),nLod(0),szPropsOverride(0) {};
[Code] ....
Okay, so for an assignment I need to write a function called find() that returns a reference to a vector. So I have vector <int> & find(string & key); If I do this, I get the obvious warning warning: reference to local variable 'lineNum' returned [enabled by default].
If I do vector<int> & find(string & key) const; I get a huge error that starts out like
In member function 'std::vector<int>& index_table::find(std::string&) const':
indextable.cpp:74:30: error: no match for 'operator='
Am I using the const identifier incorrectly?
I have this code here that counts the number of alphabetic letters the user's input,the number of characters total, the number of words and the number of "the" that was used. However now I need to alter the user's input to have two spaces after the end of each period, no spaces between a word or comma and each sentence has to have a capitalized letter and display them at the end. And I'm stuck on the altering part. I briefly started the 2 spaces after each period but it won't display anything.
#include <cstring>
#include <iostream>
using namespace std;
int main ()
[code]....
I've got a static variable in the master file called :
static dtNavMesh *g_navMesh;
I just need one copy of this object.
In another module, I need to reference this global variable.
extern dtNavMesh *g_navMesh;
What is wrong with assigning a reference variable to another reference variable of the same type? I guess I have not understood references very well.
1- In below code, the initialization list gets error because agent "object reference variable" cannot be initialized with a reference variable of the same type.
Code:
class Intention {
public:
Intention(Agent& agent,int Id, string name);
[Code] ....
In other places I have the same problem. In below code the assignment gets error (no overloaded function for assigning a reference to another reference?)
Code:
void Agent::setWorld(World& world) {
this->world = world;
}
//Note: this->world has a type of World&
2- In this other one, I want to assign reference of a vector member to a reference variable of the same type.
Code:
vector<Intention> intentions;
...
Intention& currentIntention = intentions[intentionsIterator]
Is it possible to alter an error message for a particular line if you think it might fail compilation? GNU specific stuff is okay. The reason I want to do it is because I have this code.
Code:
template <size_t S>
struct assertion{}
int main(){
{
volatile assertion<sizeof(config::input)> asrt = assertion<sizeof(config::output)>();
}
}
If the arrays config::input and config:utput are different sizes, I want it to be clear that that's what needs to be fixed. Is there an __attribute somewhere that will allow me to do that?
I don't understand how my code not run.
#include "stdafx.h"
#include<iostream>
using namespace std;
struct student{
char name[30];
char birthday[20];
char homeness[50];
float math;
[Code] ....
I have a flash movie that is bigger than the axShockwaveFlash placeholder that plays it. The axShockwaveFlash placeholder expands to the size of the movie.
I have found a website at [URL] but asp is totaly different from c#.
How can I make the movie shrink to fit in the axShockwaveFlash placeholder?
i want to store reference to a const object in my class as a member variable, as follow:
I basically want a readonly reference to |Data| in Device object.
Code:
class Device {
Device(const QList<QSharedPointer<Data>> & dataList) : _listRef(dataList) {
} protected:
const QList<QSharedPointer<Data>> & _listRef;
}
This does not allow me to initialize _listRef as something like NULL when it is not applicable.Also, i must change all my constructors and its child class to include an initialization of _listRef!!
What is the alternative? Is pointer the nearest? which of the following should be used?
Code:
const QList<QSharedPointer<Data>> * _listRef;
or
const QList<QSharedPointer<Data>> *const _listRef;
or
const QSharedPointer<QList<QSharedPointer<Data>>> _listRef; ????
I want to get a random number from this function but idk if I did this function right....
int random(int x) {
srand(static_cast<unsigned int>(time(0)));
int randomN = rand();
x = (randomN % 10) + 1;
return x;
}
So I have been working my way through this assignment and I'm just stuck now. I cannot get this work properly It just tells me I'm trying to return a local variable when attempting to return postfix in the to_postfix function. It is line 97 that wont compile. Also I cannot change anything in runner.c.
Calculator.c
Code:
1 #include <stdio.h>
2 #include <stdlib.h>
3 #include <ctype.h>
4 #include <string.h>
5 #include "stack.h"
[Code] .....
I am modifying a set of static variables inside of the class's member function. The static variables are private. An example of what I'm doing is as below,
utilities.h
-----------
class utilities {
private:
static int num_nodes;
public:
void parse_details(char* );
[Code] ....
I get a compilation error in the function void utilities::parse_details(char* filename)
which says: undefined reference to `utilities::num_nodes'
compiler: g++
I am making a function that will return a pointer to a long long variable. For example, I have the next variable prototype: Code: long long funcName(long long x, int s); I want to change the return value, and the first parameter to pointers to long long.
View 4 Replies View RelatedI need to create a loop to return a minimum value using a boolean variable but don't quite understand how to format my algorithm.
#include <iostream>
using namespace std;
int main() {
bool first = true;
while (first) {
cout << "Enter a number (X to exit): ";
int num;
[Code]....
I know its jacked up any comments in the code would be great I need to finish the program but also understand it.
I'm writing some functions pertaining to binary trees. I've used recursion once before while learning quicksort but am still quite new and unfamiliar with it. And this is my first time touching a binary tree. So my question: In my addnode function, will the return root statement at the end ever return a value other than the value passed to the function?
Code:
#include <stdlib.h>
struct tnode
{
int data;
struct tnode * left;
struct tnode * right;
}
[code]....
My program compiles but doesn't run, Here is the screen shot of debugging
//DynBag.cpp : Implementation File
#include <stdexcept>
#include <iostream>
#include "DynBag.h"
[Code] .....
I just dont see what the issue is here. I have stared at this thing forever. Im trying to make a calendar from scratch so I can be prepared for my second test on Friday.
Code:
#include<stdio.h>
#include<stdlib.h>
int main(void)
{
int i, n, s;
[Code]....
I am writing a program that expands array list whenever they get too full...so far i have this:
Code:
#define DEFAULT 10
typedef struct ArrayList {
//array of strings
char **array;
[code]....
So, ArrayList *myList should return a pointer to the new arraylist or null if malloc fails. what exactly I need to set my maximum to, I know that it shouldn't be 0 and array[i] doesn't seem to be working either. I also am not sure if I am properly setting up null correctly for my array.
#include <iostream>
#include <string>
using namespace std ;
int main() {
string bored ;
do {
cout << " program" <<endl ;
[Code] .....
I made this as a simple do/while program, and if i run it, the second do/while statement will keep on going forever, without the [cin >> bored;] line working?
I just wanna have a very simple function that reads values from a text file row by row. The first value is passed along from the stringstream to my float data[] but after that it doesn't pass along anything. The strange part (for me at least) is that the stringstream contains the values it should contain, but they doesn't wanna end up in data[].
main.cpp
#include <fstream>
#include <iostream>
#include <string>
#include <sstream>
[Code]....
I've implemented it a bit differently: I create 2 temporary arrays, one for the numbers lower from the pivot , an done for numbers greater then the pivot. in the end of each iteration the 2 arrays are copied to the original array:
Code: #include <iostream>
void QuickSort (int* A , int start, int end){
if (end-start<3){
return;
}
int mid=(start+end)/2;
int pivot=A[mid];
int lA[end-start] , rA[end-start], rCounter=0,lCounter=0;
int curr=0,i=start;
[code]....