I have this class:
boer.h
#pragma once
#include <functional>
#include <iostream>
class boer
{
private:
std::function<void(int id_)> someFun;
public:
boer();
~boer();
void setSomeFun(std::function<void(int id_)> someFun_);
void getSomeFun();
};
boer.cpp
#include "boer.h"
boer::boer() { }
boer::~boer() { }
void boer::setSomeFun(std::function<void(int id_)> someFun_)
{
someFun = someFun_;
}
void boer::getSomeFun()
{
someFun(12345);
}
And this class:
aircraft.h
#pragma once
#include <functional>
#include <iostream>
#include "boer.h"
class aircraft
{
private:
boer Boer;
public:
aircraft();
~aircraft();
void source_forSomeFun(int id_);
};
aircraft.cpp
#include "aircraft.h"
aircraft::aircraft() { }
aircraft::~aircraft() { }
void aircraft::source_forSomeFun(int lol_)
{
std::cout << "AMAZING!!!" << std::endl;
}
And I need to connect void source_forSomeFun(int id_); in aicraft with std::function<void(int id_)> someFun; in boer. How can I do this? Maybe there is another way, but i think this method is the most preferable.
int main()
{
aircraft Aircraft;
boer Boer;
Boer.setSomeFun(???); // here
Boer.getSomeFun();
int i;
std::cin >> i;
return 0;
}
Boer.setSomeFun([&](int v){aircraft.source_forSomeFun(v);});
Use a lambda.
Related
When I printed the variables passed through, the default is printed first, followed by what I want passed. So the final result remains the same. The initialization is found in Owner.h and Owner.cpp. Variables are passed starting from the Dog.cpp. I've also tried changing my print statements to Dog.owner... but the result was the same.
Owner.h
#define OWNER_H
#include <iostream>
#include <string>
#include "Dog.h"
using namespace std;
class Owner {
private:
string name;
int age;
public:
Owner(string ownerName = "Lucy" , int ownerAge = 10); // default params
string getName();
int getAge();
};
#endif
Owner.cpp
#include <iostream>
#include <string>
#include "Dog.h"
using namespace std;
// Getters
string Owner::getName() {return name;}
int Owner::getAge() {return age;}
// Constructors
Owner::Owner(string ownerName, int ownerAge) :name(ownerName), age(ownerAge) {
Owner::getName();
Owner::getAge();
}
Dog.h
#ifndef DOG_H
#define DOG_H
#include <iostream>
#include <string>
#include "Owner.h"
using namespace std;
class Dog {
private:
string breed;
int age;
Owner owner;
static int dogCount;
public:
Dog();
Dog(string, int);
// Getter and Setter methods
void setBreed(string var);
void setAge(int var);
string getBreed();
int getAge();
// Other
void printDogInfo();
static int getDogCount() {return dogCount;}
};
#endif
Dog.cpp
#include <iostream>
#include <string>
#include "Dog.h"
#include "Owner.h"
using namespace std;
// Constructors
Dog::Dog(string ownerName, int ownerAge) {
Owner(ownerName, ownerAge);
dogCount++;
}
Dog::Dog() {
}
void Dog::printDogInfo() {
cout << "owner: " << owner.getName() << ", " << owner.getAge() << " yo" << endl << endl;
}
int main() {
Dog myDog1("Belle", 15);
myDog1.setBreed("Siberian Husky");
myDog1.setAge(2);
myDog1.printDogInfo();
return 0;
}
Dog::Dog(string ownerName, int ownerAge) {
Owner(ownerName, ownerAge);
dogCount++;
}
By:
Dog::Dog(string ownerName, int ownerAge) : Owner(ownerName, ownerAge) {
dogCount++;
}
Probably, you also want to fix this:
Owner::Owner(string ownerName, int ownerAge) :name(ownerName), age(ownerAge) {
// Owner::getName(); not needed
// Owner::getAge(); not needed
}
Dog::Dog(string ownerName, int ownerAge) {
Owner(ownerName, ownerAge);
dogCount++;
}
is equivalent to
Dog::Dog(string ownerName, int ownerAge) :
breed(),
owner()
{
Owner(ownerName, ownerAge); // Create temporary
dogCount++;
}
You probably want instead:
Dog::Dog(string ownerName, int ownerAge) :
breed(),
age(0),
owner(ownerName, ownerAge)
{
dogCount++;
}
I am trying to use boost::function with instance methods using the following example
class someclass
{
public:
int DoIt(float f, std::string s1)
{
return 0;
}
int test(boost::function<int(float, std::string)> funct)
{
//Funct should be pointing to DoIt method here
funct(12,"SomeStringToPass");
}
void caller()
{
test(DoIt); //Error : 'someclass::DoIt': function call missing argument list; use '&someclass::DoIt' to create a pointer to member
}
};
Any suggestion on how I could resolve this issue ?
You should use boost::bind:
#include <boost/function.hpp>
#include <boost/bind.hpp>
#include <string>
#include <iostream>
using namespace std;
class someclass
{
public:
int DoIt(float f, std::string s1)
{
return 0;
}
int test(boost::function<int(float, std::string)> funct)
{
return funct(5.0, "hello");
}
void caller()
{
cout << test(boost::bind(&someclass::DoIt, this, _1, _2)) << endl;
}
};
int main() {
someclass s;
s.caller();
}
I have a class that I inline'd the constructor and the destructor and I also have a static method for that class. I called that static method inside of the inline destructor, but I'm having a linker error undefined reference for that static method. I'm pretty sure it is compiled and link with the object. Here is the code,
// CFoo.h
namespace barname {
class CFoo
{
public:
CFoo();
~CFoo();
static void fooMethod();
};
inline CFoo::CFoo()
{
}
inline CFoo::~CFoo()
{
fooMethod();
}
}
// SomeOtherSource.cpp
namespace barname
{
void CFoo::fooMethod()
{
}
}
It seems the code is fine and compiling.
Here is a slightly modified working version of the code
Coliru example
#include <iostream>
#include <string>
#include <vector>
namespace barname
{
class CFoo
{
public:
CFoo();
~CFoo();
static void fooMethod();
};
inline CFoo::CFoo()
{
}
inline CFoo::~CFoo()
{
fooMethod();
}
void CFoo::fooMethod()
{
std::cout << "in fooMethod" << std::endl;
}
}
int main()
{
barname::CFoo *f = new barname::CFoo();
delete f;
}
#ifndef con001_CFoo_h
#define con001_CFoo_h
namespace barname {
class CFoo
{
public:
CFoo();
~CFoo();
static void fooMethod();
};
inline CFoo::CFoo()
{
}
inline CFoo::~CFoo()
{
}
}
#endif
in other file
#include "CFoo.h"
namespace barname
{
void CFoo::fooMethod()
{
}
}
compiled ok in XCode 4.6
This was my original code
#include "stdafx.h"
#include <string>
#include <list>
#include <algorithm>
using namespace std;
class testing
{
public:
int value;
testing(int v)
{
value = v;
}
int getval()
{
return(value);
}
};
void func(testing& ob)
{
printf("The value is %d\n", ob.value);
}
int _tmain(int argc, _TCHAR* argv[])
{
std::list<testing> testvar[3];
testing t1(0);
testing t2(1);
testing t3(3);
testvar[0].push_back(t1);
testvar[0].push_back(t2);
testvar[0].push_back(t3);
std::for_each(testvar[0].begin(), testvar[0].end(), func);
printf("Reached End");
getchar();
return 0;
}
I modified it to make func a member function and got weird compile errors, I searched online and someone had told use bind1st, bind2nd
#include "stdafx.h"
#include <string>
#include <list>
#include <algorithm>
using namespace std;
class testing
{
public:
int value;
testing(int v)
{
value = v;
}
int getval()
{
return(value);
}
};
class testing2
{
public:
std::list<testing> testvar[3];
void func(testing& ob)
{
printf("The value is %d\n", ob.value);
}
void driver()
{
std::for_each(testvar[0].begin(), testvar[0].end(), func);
}
};
int _tmain(int argc, _TCHAR* argv[])
{
testing2 testob;
testob.driver();
printf("Reached End");
getchar();
return 0;
}
So I modified the driver function to this
void driver()
{
std::for_each(testvar[0].begin(), testvar[0].end(), std::bind1st(std::mem_fun(&testing2::func), this));
}
I still get some weird compile erros, could someone please expain why we need to call a member function is such weird way..? and how does bind1st help..?
Use std::bind
std::for_each(testvar[0].begin(), testvar[0].end(), std::bind(&testing2::func, this, std::placeholders::_1));
Or use std::bind/lambdas
std::for_each(testvar[0].begin(), testvar[0].end(), [this](testing& ob) { func(ob); });
Full:
#include <string>
#include <list>
#include <algorithm>
using namespace std;
struct testing {
int value;
testing(int v) { value = v; }
int getval() { return(value); }
};
struct testing2 {
std::list<testing> testvar[3];
void func(testing& ob) {
printf("The value is %d\n", ob.value);
}
void driver() {
auto f = std::bind(&testing2::func, this, std::placeholders::_1);
std::for_each(testvar[0].begin(), testvar[0].end(), f);
std::for_each(testvar[0].begin(), testvar[0].end(), [this](testing& ob) { func(ob); });
}
};
int main() {
testing2 testob;
testob.driver();
printf("Reached End");
}
You can also use std::mem_fn for cleaner syntax like this:
std::for_each(testvar[0].begin(), testvar[0].end(), std::mem_fn(&testing::func));
Complete code:
#include <stdio.h>
#include <bits/stdc++.h>
class testing
{
public:
testing(int v) : value(v) {}
int getval() {
return(value);
}
void func()
{
printf("The value is %d\n", value);
}
private:
int value;
};
int main() {
std::list<testing> testvar[3];
testing t1(0);
testing t2(1);
testing t3(3);
testvar[0].push_back(t1);
testvar[0].push_back(t2);
testvar[0].push_back(t3);
std::for_each(testvar[0].begin(), testvar[0].end(), std::mem_fn(&testing::func));
return 0;
}
Below is my code
#include "stdafx.h"
#include <string.h>
#include <iostream.h>
using namespace std;
class ToDoCommands
{
public:
void getCommand(string);
};
void ToDoCommands::getCommand(string command)
{
cout<<command; //here i get ping
void (*CommandToCall)(void);
CommandToCall = command; // error here i want something like
// CommandToCall = ping
CommandToCall();
}
void ping(void)
{
cout<<"ping command executed";
}
int main()
{
ToDoCommands obj;
obj.getCommand("ping");
}
The function pointer should refer to function ping dynamically. A string same as function name is passed to getCommand function in main.
C++ just doesn't work that way. If you really need something like that, you'll have to make a table of functions that are indexed by name:
#include <assert.h>
#include <iostream>
#include <map>
#include <string>
using std::cout;
using std::string;
using std::map;
void ping(void)
{
cout << "ping command executed\n";
}
class ToDoCommands
{
public:
typedef void (*FunctionPtr)();
typedef string Name;
void registerFunction(Name name,FunctionPtr);
void callFunction(Name);
private:
map<Name,FunctionPtr> func_map;
};
void ToDoCommands::registerFunction(Name name,FunctionPtr func_ptr)
{
func_map[name] = func_ptr;
}
void ToDoCommands::callFunction(Name name)
{
assert(func_map.find(name)!=func_map.end());
func_map[name]();
}
int main(int argc,char **argv)
{
ToDoCommands to_do_commands;
to_do_commands.registerFunction("ping",ping);
to_do_commands.callFunction("ping");
return 0;
}
void ping(void)
{
// LL DD…DD XX
cout<<"ping command executed"<<endl;
}
class ToDoCommands
{
public:
void getCommand( void (*CommandToCall)(void)); //getCommand(ping)
};
void ToDoCommands::getCommand( void (*CommandToCall)(void) )
{
void (*CommandToCall1)(void);
CommandToCall1 = CommandToCall;
CommandToCall1();
}
int main()
{
ToDoCommands obj;
obj.getCommand( ping );
return 0;
}
i tried this and its working :)