I've written some code that I am currently threading but I am unsure how to pass by reference, or rather why my pass by reference is failing.
I am passing an array of floats by reference, this works fine when not threaded but I am given the error that float*&field does not match std::reference_wrapper<float*>.
I've been given an assignment with the below questions.
1. What is the difference between pass by reference & pass by pointers?
2. What is the use of the initialization list in the constructor?
3. What is meant by a reference & its advantage?
4. Class has a reference, pointer and a const. Is it possible to write the copy constructor & assignment operator overloading funciton? how? ( Since reference is there, I'm not sure on how to write for it)
5. Example for a variable decleration and definition? (I know for function but for variable don kw how)
6. static and const static what is the difference??
i think i understand both concept. i know that pass by value is that the function receiving those values makes actually a copy of those parameters. Passing by reference makes the variable in the main function to actually see those changes in the other function, instead of a copy, and apply them to the variable in the main function. my question is, why would i pass it by reference if i just can make a return type function.
Write a complete C++ program with the two alternate functions specified below, each of which simply triples the variable count defined in main. Then compare and contrast the two approaches. These two functions are
a) function tripleByValue that passes a copy of count by value, triples the copy and returns the new value and
b) function tripleByReference that passes count by reference via a reference parameter and triples the original value of count through its alias (i.e., the reference parameter).
I built a program that finds the average amount of days missed per employee. I am now attempting to modify my program to pass values by reference rather than passing by value. I created 3 functions: int numOfEmployees(); int numOfDays(int); double avgDays(int, int);
in the prototype I use the ampersand sign int numOfDays(int&); in the actual function I use numOfDays(int& employees)
I am just not able to get the call to the function to work the program will crash when I modify it with the ampersand signs.This is the original code I am trying to modify:
#include <iostream> using namespace std; int numOfEmployees(); //Prototype for numOfEmployees int numOfDays(int); //Prototype for numOfDays double avgDays(int, int); //Prototype for avgDays
I built a program that finds the average amount of days missed per employee. I am now attempting to modify my program to pass values by reference rather than passing by value. I created 3 functions:
int numOfEmployees(); int numOfDays(int); double avgDays(int, int);
in the prototype I use the ampersand sign int numOfDays(int&); in the actual function I use numOfDays(int& employees)
I am just not able to get the call to the function to work the program will crash when I modify it with the ampersand signs. I know I have to re-work my program, but I am having a hard time understanding how.
This is the original code I am trying to modify:
#include <iostream> using namespace std; int numOfEmployees(); //Prototype for numOfEmployees int numOfDays(int); //Prototype for numOfDays double avgDays(int, int); //Prototype for avgDays
I am having trouble working with third party dll's, libs and header files. I am trying to call a function.here is the function that is suppose to be called.
Name IN/OUT Description m_environment IN Optional. Possible values are SANDBOX (default) and LIVE. m_strConsumerKey IN OAuth consumer key provided by E*TRADE m_strConsumerSecret IN OAuth consumer secret provided by E*TRADE m_strToken OUT Returned by the function if successful m_strTokenSecret OUT Returned by the function if successful m_strCallback IN Optional; default value is "oob"
What is the difference in pass by pointer and pass by reference? As per my understanding, there is no difference much.If a function accepts pointer, then NULL check can be performed.other than this i'm not able to see any big difference..
Now when I want to access that array, I have the following:
ptrSomeStruct->structArray[someIndex];
But now I want to pass structArray to this function by reference so that it can adjust the array as needed and I can continue to use the array back in my caller function:
I just want to know if there is any real difference between the two below, if yes, when would i use one over the other? I would thought the "&" is pointless in below function, as far as the data is concerned.., the only things is with "&", if the pointer address value is changed in Test function, it will affect the caller's copy of data. Both function should behave the same if data is changed.
Due to the nature of this requirement, I've made a very minimal example, which would adequately solve my issue, without resorting to use of pointers or copy constructors.
Basically I'm trying to pass an object as a reference to the template function, rather than a copy as it's seeing. I'm needing to do this without editing Obj::Call to accommodate a reference as its first parameter, as it'd break other calls.
You'll notice in the following code the object will be destroyed upon passing, while the object defined is still in-scope due to the infinite end loop.
#include <iostream> #include <string> using namespace std; class Obj { public: string name;
[Code] ....
In the past I tried ref(), which appeared to stop this happening, however it created a blank copy of the object instead.
I am trying use a print function to print out data in a struct. My questions are:
1. I have to use pass by reference. For the print function, I am passing the struct pointer as a reference, however, I don't want the print function to accidentally change anything. How can I make it use const to ensure that?
2. The deleteprt function doesn't look right to me. I feel like it should just be delete ptr not delete [] ptr.
This is confusing to me because it compiles, yet my unique i is passed by R-value reference, without ever being explicitly moved. I thought named objects could NEVER be considered R-value references... Am I wrong to think that the above is extremely dangerous? After the call to "eat", my "i" has been destroyed internally, I could save by passing by value:
But at this point, I'm paying for a (theoretically cheap) move copy, when I could be paying nothing at all... A third solution would be to overload with a const ref version, but at this point, I get an obscure linker error, when I'm really looking for a compiler error...
i have a project where i create a dice game, the user rolls 2 dice and the computer roles 2 dice. the player that wins 3 out of 5 rolls wins the game. I have completed the requirements, but i wanted to create a pass by value function for "void Dice()", I'm not too sure how that works?
Code:
#include <iostream> #include <ctime> #include <cstdlib> using namespace std; //creating my variables and their values int compinput;
i really don't know why has a error in my code, that pass a pointer of pointer (name of a matrix with 2 dimensions). Here is the source code of a simple example where appears segmentation fault when execute (but compiles normal):
#include <stdio.h> #define LINHAS 3 #define COLUNAS 5 float a[LINHAS][COLUNAS]; void zeros(float **p,float m, float n){ int i,j; for(i=0;i<m;i++)
I wrote code that finds the number of prime numbers in a range entered by the user. Now I'm attempting to make it run in parallel with the number of threads I assign it to have. I'm using blocking technique, so I'm assigning, in this scenario, 4 threads - 1/4 of the numbers in the range to the first array, and the next 1/4 of the numbers in the range to the next array and so on. Then I want to execute the prime number counting code in parallel. I'm using openMP to do this. I'm having difficulty setting it all up properly. I have a little experience with pthreads but little with openMP and am struggling in how this should be done.
I'm wondering if there is a library for C++ that supports threading over the network, maybe with a threading pool and a specific protocol; or if there is just a de-facto protocol for doing threading over the network.
