I have a class and I would like to be able to pass an extra parameter to the function that is executed.
BigInt operator / (BigInt N,BigInt D) {
...
}
is what I have now. but I would like to do something like this. so the default value for a is 10. and if the user does something like N/D (12) Then the value of a is 12.
BigInt operator / (BigInt N,BigInt D, int a=10) {
...
}
I have a class matrixType that has some overloaded operators (+, -, *, and <<). With a view to having clearly-delineated, perfectly-formatted, four-sided matrices, as shown below:
A = 1 2 3
4 5 6
7 8 9
or
A + B = 1 2 3
4 5 6
7 8 9
and NOT this jagged ones shown below:
A = 1 2 3
4 5 6
7 8 9
or
A + B = 1 2 3
4 5 6
7 8 9
,
I want a scheme in which the string literals (A, A+B, etc.) could be passed as parameters to the overloaded stream insertion (<<) operator function so that I could use the string’s length to determine how much offset from the display screen’s left to apply to each matrix’s row (by using the setw() function). However, I do know that the << operator is a binary operator, meaning the function cannot take more than two parameters: that is what compounds my problem!
gcc v.8.3 -std=gnu++11
[URL]
I'm trying to pass a function as a parameter and failing. It seems simple, until I get the error messages.
Here is the code:
class MinimalSolver {
typedef double (*func)(double sum, double char);
void driver();
[Code]....
How come when we pass an array as a parameter to a function, the entire array is copied and is available to function?
View 1 Replies View RelatedWrite a program that inputs 10 integers from the console into an array, and removes the duplicate array elements and prints the array. By removing, I mean that you should make it appear as if the elements hadn't been there. You may assume that all the integers are between 0 and 100, Write at least 1 function in addition to the main function, and pass an array into that function as a parameter. e.g.
Please enter your 10 numbers: 1 2 3 4 5 6 7 8 9 10 The array contains: 1 2 3 4 5 6 7 8 9 10
Please enter your 10 numbers: 1 1 3 3 3 6 7 8 9 9 The array contains: 1 3 6 7 8 9
Please enter your 10 numbers: 1 1 1 1 1 1 1 1 1 1 The array contains: 1
The bolded area is where I'm having trouble. How I can go about doing this, passing an array into the function as a parameter?
Here is my code:
#include "stdafx.h"
#include <iostream>
using namespace std;
int main () {
const int MAX = 10;
int a[MAX] = {0};
int i;
[Code]...
Pseudocode:
template<typename T /*, some parameter for member_function */>
class Foo {
public:
void someFunction() {
T t;
t.member_fuction(...);
} }
I'm trying to make the call to T::member_function a templated value because member_function might vary by name in my scenario. Since std::mem_fn isn't a 'type', i can't do something like Foo<std::string, std::mem_fn(&std::string::clear)> foo;
I also want to take into account that member_function might have more than one parameter. That is, the first parameter will always be something known but there might be other defaulted parameters.
The only thing I can think of is to make a proxy structure, something like this:
template<typename T, T> struct proxy;
template<typename T, typename R, typename... Args, R (T::*member_function)(Args...)>
struct proxy<R (T::*)(Args...), member_function> {
R operator()(T &obj, Args.. args) {
return (obj.*member_function)(std::forward<Args>(args)...);
} }
Which would then allow me to do (for example) this:
Foo<std::string, proxy<void(std::string::*)(), &std::string::clear> >
when Foo is implemented like this:
template<typename T, typename member_function>
class Foo {
public:
void someFunction() {
T t;
member_function()(t);
} };
That implementation works for me.
I created the following code to pass the the variable 'inputVoltage' by reference to the function 'input'. It certainly works when I run the program, but I dont think it is a standard way of doing it, i.e. the use of '*' and '&' is not according to convention ? Or perhaps the way did it is acceptable ?
int input (double *inputVoltage);
int main ( {
double inputVoltage;
input(&inputVoltage);
[Code]....
While running it gives the runtime error: "Extra parameter in call to factorial."
#include<iostream.h>
#include<conio.h>
int factorial(long int);
void main() {
clrscr();
long int a;
cout<<"This program displays the factorial of the number you enter."<<endl;
[Code] .....
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;
Obj(string name): name(name) {cout << "create " << this << endl;}
[code]....
In the past I tried ref(), which appeared to stop this happening, however it created a blank copy of the object instead.
#include<iostream.h>
#include<conio.h>
#include<stdio.h>
void count();
void main() {
char c[100];
cout<<"Enter a string upto 99 characters(spaces included):"<<endl;
[Code] ....
The thing is, when I don't create a prototype of count and straightaway define it before void main() my program runs, but it gives error in this program that "extra parameter in call to count()" But what to do then?
[URL]
class CMyclass
{
public:
CMyClass(BOOL bUseWhichMemManager);
void* operator new(size_t);
void operator delete(void*);
};
I create two memory manager called CMemManager1 and CMemMangaer2, using different algorithms to allocate buffer. Now I want to control which memory manager to be used, when calling new.
I try to add a parameter bUseWhichMemManager to the constructor, but in overrided new function, there are no way to access the parameter. Is there a way to pass more parameters to new operator, such as:
void* operator new(size_t size, BOOL bUseWhichManager);
My errors are at the end of the program in two function calls within the definition of the InsertByValue function. g++ does not seem to recognize NumArray as a valid parameter.
#include <iostream>
#include <assert.h>
using namespace std;
const int CAPACITY = 20;
/* Displays the content of an int array, both the array and the size of array will be passed as parameters to the function
@param array: gives the array to be displayed
@param array_size: gives the number of elements in the array */
void DisplayArray (int array[], int array_size);
[Code] ....
In a .h file there is a function that takes in this parameter:
void (^callback)(float * arg)=NULL
as in a function definition:
void func(void (^callback)(float * arg)=NULL);
What I am able to read is that it takes a function pointer and if not defined it overrides with NULL. The part I do not get is the ^ in (^callback). I only know ^ as a bitwise XOR operator. It also generates issues in my VS2012 compiler (something with CLR). So I would really like to rewrite this part to something else, without the bitwise operator...
Code:
#include <stdio.h>
void ASCII_to_EBCDIC( size_t, unsigned char *);
void EBCDIC_to_ASCII( size_t, unsigned char *);
void to_ASCII(unsigned char *);
void to_EBCDIC(unsigned char *);
/* conversion tables */
static unsigned char
[Code] ....
The above snippet is for a buffer/string, where as i want to pass file name as a parameter and want function to process the file line by line?
#include <cstdlib>
#include <iostream>
struct tax_node {
char form; // tax form letter
int version; // tax form number
[Code] ....
I cannot seem to get why function print_contents will not work. The couts at the end of the program is just to test that it printed correctly. But, if I need it to print the contents such when print_contents(ptr2) is called. I think it should be tax_ptr in the parameter list but I am not quite sure.
I want to create events and then, functions which are subscribed to the event can access information about the event. For example, in Class 2 below, I want it to be able to access things such as touch.position, etc. of class 1.
Class 1:
public delegate void TouchEventHandler (EventArgs e);
public event TouchEventHandler TouchBegan;
public Vector2 touchPosition;
void Update () {
if (Input.touchCount > 0) {
[Code] ...
Class 2:
void OnTouchBegan (EventArgs e) {
Debug.Log ("Ran");
}
I've been playing around with this piece of code:
#include <iostream>
#include <string>
#include <algorithm>
template <void(*funky)(const std::string&)>
void callback()
{funky("Hello World!");}
[Code] ....
But when I try to build it, I get this error on line 24:could not convert template argument 'lambda' to 'void (*)(const string&) {aka void (*)(const std::basic_string<char>&)}'|
I thought the lambda expression I wrote would decay to a function pointer matching the template parameter. I can guess that the constexpr qualifier might have changed the type, but without it my compiler complains that lambda needs to be declared as constexpr...
So is there a way to pass lambda expressions as template parameters?
Without having to use std::function
Here is my issue: I am making a simple audioplayer in Xamarin.android but i want every time i change the track to make a crossfade effect. So im using 2 mediaplayers at the same time for the fade. The problem is that im defining one time the players and i pass the player as a parameter like this:
public MediaPlayer player = null;
public MediaPlayer player2 = null;
....
If i have to fadeout the player and start the next one im doing it like this:
if (player != null){
if (player.IsPlaying) {
cts = new CancellationTokenSource();
token = cts.Token;
FadeOut (player, 2000 ,token);
[Code] .....
So my problmem is that player and player2 remain always null. Why? i guess c# creates a copy of player and player2 and use this one. How i can pass a mediaplayer as parameter and always use only player and player2?
Does putting a ref when passing a struct to a parameter work? Say i have this code
struct struct1 {
public int i;
public void show() {
Console.WriteLine(i);
[Code] ....
The output doesn't change. The result is
0
100
500
0
I've was trying out a function template to automatically get the type of a lambda, but it seems that it won't compile
I've tried two different ways:
1.
template<class HASHER>
auto make_unordered_map(size_t bucketCount, HASHER const && hf)
-> unordered_map<string const, HASHER>&& {
return unordered_map<string const, int, HASHER>(bucketCount, hf);
} auto x = make_unordered_map(1, [](string const& key)->size_t { return key[0]; });
2.
template<class HASHER>
auto make_unordered_map(size_t bucketCount, HASHER const && hf2)
-> unordered_map<string const, int, decltype(hf2)> {
return unordered_map<string const, int, decltype(hf2)>(bucketCount, hf2);
} auto x = make_unordered_map(1, [](string const& key)->size_t { return key[0]; });
The test code are located here:
1. [URL] ....
2. [URL] ....
They are both based on the code that is stated to work in those examples. I.e.:
auto hf = [](string const& key)->size_t { return key[0]; };
unordered_map<string const, int, decltype(hf)> m (1, hf);
Why it is necessary to use the reference operator here ?
const string& content() const {return data;}
Example in [URL] ....
// classes and default constructors
#include <iostream>
#include <string>
using namespace std;
class Example3 {
string data;
[Code] .....
error says "cannot convert 'int*' to 'int' in function main()
and also
type mismatch in parameter in function sort(int,int)
Heres the code:
#include<iostream.h>
#include<conio.h>
void main() {
void sort(int,int);
clrscr();
[Code] .....
I have a class as below:
// RemoteControlMonitor.H
typedef void (*keyaction)(unsigned int key);
class RemoteControlMonitor {
private:
keyaction rph;
keyaction rrh;
[Code] .....
But I got compile error as below:
RemoteControlMonitor.H:58: invalid type `void *' for default argument to `void (*)(unsigned int)'
rcx1.C: In function `void __static_initialization_and_destruction_0(int, int)':
rcx1.C:54: ANSI C++ forbids implicit conversion from `void *' in default argument
What can I do?
How I can delete a parameter in a function .
int *buildTrail(int antIndex, int start, double *pheromones) {
int *trail = new int[tabu];
bool *visited = new bool[tabu];
trail[0] = start;
visited[start] = true;
[Code] ....
If I comment all lines includes visited word , no exception occurs , Otherwise , exception throws.
Simply put , How can i delete visited parameter as long as its role has been finished?
.
.
.
delete visited ;
return trail;
void foo(FILE *f1, FILE **f2) {
fputs("...", f1);
fputs("...", *f2);
} int main(void) {
FILE *fp1 = fopen(...),
*fp2 = fopen(...);
if(fp1 && fp2) {
foo(fp1, &fp2);
...
}
...
}
Forever, I've passed FILE objects into functions like the first parameter; I've never had an issue reading or writing files using that form - no file errors, no compiler warnings, etc. Recently, I saw the second parameter form, and wondered why that was?
I still don't quite get this part of pointers. What's the second parameter form doing differently than the first when the first version *appears* to work as intended??
Is there any function which can return parameter list of a function.
For example : get_param(f(int x,char y )) return parameter x-> int y-> char
and f_name ->f