I'am trying to save the values to container, but add identidier not found.
I can not also call function Array::add(*train)
Error C2352 'Array::add': illegal call of non-static member function
Train* train = new Train(number, path, time_of_departure);
train->print();
add(*train);
//void contains();
return train;
Container
#include <iostream>
#include <vector>
#include "Array.h"
//#include <vector>
using namespace std;
Array::Array() {}
void Array::add(Train &train)
{
trains.push_back(train);
}
What am I doing wrong?
Full code: https://github.com/brenqP/stack50/tree/process/500
As the error msg suggest, you are calling the add msg like it were static
what you instead have to do is use the object and call add method
your custom class array looks like this:
class Array
{
private:
vector<Train>trains;
public:
Array();
void add(Train&train);
Train find();
};
so you can do something like:
{
Array x;
x.add(*train)
}
Illegal call of non-static member function means that you are trying to call the function without using an object of the class that contains the function.
Related
I need to build a vector of a class that can have multiple type like this:
#include <variant>
#include <vector>
#include "Field.h"
using namespace std;
int main()
{
variant <int, float> v;
vector <variant<Field<int>, Field<string>, Field<float>>> fdList;
fdList[0].getName();
}
And this is header file Field.h:
#pragma once
#include <string>
#include <vector>
using namespace std;
template<class T>
class Field
{
public:
Field();
Field(string);
void setName(string);
string getName();
bool isPrime();
void toPrime();
void toForeign(Field);
~Field();
private:
string FD_Name;
vector <T> records;
bool isPrimeK = false;
string message;
};
template<class T>
string Field<T>::getName()
{
return FD_Name;
}
When I try to access getName() function, Visual Studio keeps giving me the following message error:
E0135 class "std::variant<Field, Fieldstd::string, Field>" has no member "getName"
C2039 'getName': is not a member of 'std::variant<Field,Fieldstd::string,Field>'
But it works just fine, if I define my vector like this:
vector <Field<int>> fdList;
fdList[0].getName();
How can I fix this?
For any issue about standard library, I recommend you to check document first.
You can see here about how to use std::variant.
In short, you cannot access the content in your std::variant like that because its type is std::variant but not the types you store in it. For your case, I think you may want to check what's inside first by calling std::variant::index() method, then get the value by calling std::get.
Calling a method on variant doesn't automatically call the method of the active alternative of variant. You'll have to visit the active alternative and invoke the corresponding handler. In your case, since you want to handle all of the potential active alternatives the same way, you can do:
std::visit([](const auto& field) {
field.getName();
// ...
}, fdList[0]);
Alternatively, you can wrap the variant in something like:
struct AnyField {
string getName() const {
return std::visit([](const auto& field) { return field.getName(); }, v);
}
std::variant<Field<int>, Field<string>, Field<float>> v;
};
then use them like you wanted to:
vector<AnyField> fdList;
fdList[0].getName();
I have a problem with vector declaration and initialization in a
class constructor. I have a Station.h and Station.cpp files of a class and I recall it in main :
Station.h
#ifndef STATION_H
#define STATION_H
#include <vector>
class Station
{
public:
int num_bin;
int num_staz;
vector<int> binari; //here already gives me error! Vector does not name a type
Station(int num_staz, int num_bin);
virtual ~Station();
Station(const Station& other);
protected:
private:
};
Then I want to initialize the vector in the constructor of .cpp like that:
Station.cpp
#include "Station.h"
using namespace std;
Station::Station(int num_staz, int num_bin)
{
this->num_bin = num_bin;
this->num_staz = num_staz;
this->binari(num_bin); //here I want to create a vector of num_bin size
}
and then call it in main like that:
main.cpp
#include <iostream>
#include "Station.h"
using namespace std;
int main()
{
Station staz1(2,3);
staz1.binari.push_back(300); // error! class Station has no member binari
staz1.binari.push_back(250);
staz1.binari.push_back(150);
return 0;
}
Where am I making a mistake?
this->binari(num_bin); //here I want to create a vector of num_bin size
The function you need to use is std::vector::resize().
this->binari.resize(num_bin);
It will be better to initialize the object with the appropriate size as:
Station::Station(int num_staz, int num_bin) : num_bin(num_bin),
num_staz(num_staz),
binari(num_bin)
{
}
this->binari(num_bin); This doesn't work because it is not an initialization that is why it doesn't work.
To make this work use it in in-class initialization list:
Station::Station(int num_staz, int num_bin) :
num_bin(num_bin),
num_staz(num_staz),
binari(num_bin)
{
}
I don't know if I've missed something, but I can't seem to figure out how to make this work, and couldn't find the answer online.
Lets say I have a two classes, Class A, and Class B. (stored in separate files)
Class A has a function setName() that sets a variable within a Class A object.
Class B has a function setOtherName() that sets the value of a Class A object's name.
So I set setOtherName() up like so:
void setOtherName(ClassA& cla)
{
*cla.setName("foobar");
}
then my main script looks like so:
Class A burger;
Class B fries;
fries.setOtherName(*burger);
this does not work in my orignal script, I get the following error:
error: no matching function for call to 'ClassB::setOtherName(ClassA*&)
Any help is aprreciated! ( sorry for any confusion )
Actual code:
main.cpp:
#include <iostream>
#include "quests.h"
#include "player.h"
#include <string>
#include <cstdlib>
using namespace std;
int main()
{
quests GameQuests;
player Player;
GameQuests.quest1(Player);
Player.main();
return 0;
}
quests.cpp:
#include "quests.h"
#include "player.h"
#include <iostream>
#include <string>
#include <cstdlib>
using namespace std;
void quests::quest1(player& charact){
cout << "By the way, what was your name?" << endl;
person1=4;
system("pause");
charact->setName();
}
The implementation of your setOtherName function should have the signature
void ClassB::setOtherName(ClassA& cla)
You need to specify that it is included in ClassB. Within your class definition of ClassB, make sure to include
void setOtherName(ClassA&);
Furthermore, since your variable burger is of type ClassA and not of type ClassA*, there is no need to dereference the variable upon passing it into the function. Call it like
fries.setOtherName(burger);
You have also incorrectly dereferenced the variable cla. That object is passed by reference, not pointer, so there is no need to dereference.
You have to read about pointers and reference mate.
This is how your function should look like
void setOtherName(ClassA& cla)
{
cla.setName("foobar");
}
There is no need to deference something that is not a pointer.
ClassA burger;
ClassB fries;
fries.setOtherName(burger);
again, you don't need to dereference burger since its not a pointer.
If burger was created like this:
ClassA* burger = new ClassA();
and the function
void setOtherName(ClassA& cla)
was taking a reference, you had to dereference burger
fries.setOtherName(*burger);
Why are you derefrencing burger? You told the compiler to expect class A by reference, not by pointer.
Try:
fries.setOtherName(burger);
Also, get rid of the asterisk on setOtherName.
void setOtherName(ClassA & cla)
{
cla.setName("foobar");
}
EDIT:
Wrote a sample program of what I think you are trying to do below.
#include <iostream>
#include <string>
class Burger
{
public:
Burger(){}
void setName(std::string name){ m_name = name; }
std::string getName(){ return m_name; }
private:
std::string m_name;
};
class Fries
{
public:
Fries(){}
void setOtherName(Burger & burger){ burger.setName("FryBurger"); }
private:
};
int main()
{
Burger A;
Fries B;
B.setOtherName(A);
std::cout << A.getName() << std::endl;
return 0;
}
I'm storing a map in a class that has strings as keys and pointers to member functions as values. I'm having trouble calling the right function throw the function pointer.
Here is the code:
#include <iostream>
#include <string>
#include <map>
using namespace std;
class Preprocessor;
typedef void (Preprocessor::*function)();
class Preprocessor
{
public:
Preprocessor();
~Preprocessor();
void processing(const string before_processing);
private:
void take_new_key();
map<string, function> srch_keys;
string after_processing;
};
Preprocessor::Preprocessor()
{
srch_keys.insert(pair<string, function>(string("#define"), &Preprocessor::take_new_key));
}
Preprocessor::~Preprocessor()
{
}
void Preprocessor::processing(const string before_processing)
{
map<string, function>::iterator result = srch_keys.find("#define");
if(result != srch_keys.end())
result->second;
}
void Preprocessor::take_new_key()
{
cout << "enters here";
}
int main()
{
Preprocessor pre;
pre.processing(string("...word #define other word"));
return 0;
}
In function Preprocessor::processing if the string is found in the map then, I call the proper function. The problem is that, in this code, Preprocessor::take_new_key is never called.
Where is the mistake ?
Thanks
The correct syntax is this:
(this->*(result->second))();
That is ugly. So lets try this:
auto mem = result->second; //C++11 only
(this->*mem)();
Use whichever makes you happy.
result->second does not call the function pointer. Try ((*this).*result->second)();
I'm trying to create a vector with a specific size, of 255 (max)..
It doesnt work for me, like I see in examples over the internet...
I'm using Microsoft Visual C++ 2012...
I have the current code :
#include <iostream>
#include <string>
#include <vector>
#include <stdlib.h>
using namespace std;
const int MAX = 255;
class test
{
vector <string> Name(MAX);
};
int main()
{
system("PAUSE");
}
It gives me 2 errors :
Error 1 error C2061: syntax error : identifier 'MAX'
2 IntelliSense: variable "MAX" is not a type name
Thanks for your help!
That's not valid syntax for a class declaration. Try:
class test
{
vector <string> Name;
test() : Name(MAX) {}
};
You can write vector <string> Name(MAX); when you create a variable (in your case, you're declaring a member). For example:
int main()
{
vector <string> Name(MAX);
}
would be perfectly valid.
You can't pass arguments to the std::vector constructor int the class declaration. You should put that in the constructor for your class, like this, which utilizes does it via an initializer list:
class test
{
std::vector<std::string> Name;
public:
test():
Name(MAX)
{
}
};
You cannot initialize a data member inside the class declaration like this. Use the member initialization list in your constructor of the class to initialize vector<string> Name.
test::test
:Name(MAX)
{
//
}
Your main would be like this.
test t1 ;
It would automatically call the constructor and all the fields of t1 would be created, including vector<string> Name.