How to include file 2 in file 1. What changes I need to make in file 2.
file 1
#include <iostream>
using namespace std;
int main()
{
cout<<"Hello World";
return 0;
}
file 2
int otheFun()
{
cout<<"Demo Program";
return 0;
}
You do not include cpp files in to another cpp files.
Also, a c++ program can have only one main() function.
If you are trying to play around with a program which has multiple files, You will need to have something like this:
file2.cpp
#include <iostream>
#include "file2.h"
int printHelloWorld()
{
std::cout<<"Hello World";
return 0;
}
file2.h
#ifndef FILE2_H <----Lookup Inclusion Guards on google, this is important concept to learn.
#define FILE2_H
int printHelloWorld();
#endif //FILE2_H
file1.cpp
#include <iostream>
#include "file2.h"
int main()
{
std::cout<<"Demo Program";
printHelloWorld();
return 0;
}
What changes I need to make in file 2?
#include <iostream>
using namespace std;
int main()
{
cout << "Hello world";
cout << "Demo Program";
}
Related
I'm having an issue where I am trying to use variables stored in a struct called from a header file. I am able to call to each cpp file ie., call an action from one to another however variables are proving difficult.
Client.cpp
#include <iostream>
#include "Header.h"
#include <vector>;
#include <conio.h>;
#include <string>;
using namespace std;
int main()
{
cout << "Please enter a name: " << flush;
cin >> sNam.sNames;
main2();
return 0;
}
Admin.cpp
#include <iostream>
#include "Header.h"
#include <vector>;
#include <conio.h>;
#include <string>;
using namespace std;
void main2()
{
if (sNam.sNames == sNam1.sNames1)
{
cout << "Correct Entry...\n";
}
else if (sNam.sNames != sNam1.sNames1)
{
cout << "Incorrect Entry...\n";
}
}
Header.h
#pragma once
#include "Admin.cpp"
#include "Client.cpp"
struct Names
{
string sNames;
string sNames1 = "John";
}sNam, sNam1;
don't include cpp files
also sNam and sNam1 are defined in both cpp files, you will have link time error
include Header.h in both Client.cpp and Admin.cpp
then declare what's common in Header.h
#pragma once
// #include "Admin.cpp"
// #include "Client.cpp"
struct Names
{
string sNames;
string sNames1 = "John";
};
extern Names sNam, sNam1;
void main2();
in one of cpp files
#include "Header.h"
Names sNam, sNam1;
I have 2 two files called main.cpp and Volum_sumar.cpp. I included Volum_sumar.cpp in main.cpp header, but it doesn't see global variables in main.cpp
Can someone tell where is my mistake?
//main.cpp
#include <iostream>
#include <fstream>
#include <cstring>
#include <cmath>
#include <string>
#include <windows.h>
#include "Volum_sumar.cpp"
using namespace std;
fstream f("Figuri.txt");
fstream d("Dimens.txt");
int n=0;
struct Sfere
{
string codsf;
char culoare [15];
char material[15];
float xc,yc,r,arie,volum;
} sf[100],aux;
int main()
{
cazul3();
}
// Volum_sumar.cpp
#include <iostream>
#include <fstream>
#include <cstring>
#include <cmath>
#include <string>
#include <windows.h>
using namespace std;
void cazul3(){
double volt=0;
for(int i=0;i<n;i++)
{
volt=volt+sf[i].volum;
}
cout<<"VOLUMUL SFERELOR INREGISTRARE ESTE DE : "<<volt<<"cm3"<<endl;
}
You are going about this all wrong.
Like #CruzJean said, by including Volum_sumar.cpp directly in main.cpp, you are trying to access n and sf before they have even been defined.
#include'ing cpp files in other cpp files is bad practice. You should #include only header files. You are supposed to declare shared items in header files that cpp files can #include at needed, then compile your cpp files individually, and then finally link the resulting object files together to make the final executable file.
Global variables that need to be accessed across cpp files need to be instantiated in one cpp file and declared as extern in other files. The linker will resolve the extern references.
Try something more like this instead:
shared.h
#ifndef shared_h
#define shared_h
#include <string>
struct Sfere {
std::string codsf;
char culoare [15];
char material[15];
float xc, yc, r, arie, volum;
};
extern Sfere sf[100];
extern int n;
#endif
main.cpp
#include <fstream>
#include "shared.h"
#include "Volum_sumar.h"
std::fstream f("Figuri.txt");
std::fstream d("Dimens.txt");
int n = 0;
Sfere aux;
int main() {
cazul3();
}
Volum_sumar.h
#ifndef Volum_sumar_h
#define Volum_sumar_h
void cazul3();
#endif
Volum_sumar.cpp
#include <iostream>
#include "shared.h"
#include "Volum_sumar.h"
void cazul3() {
double volt = 0;
for(int i = 0;i < n; ++i) {
volt = volt + sf[i].volum;
}
std::cout << "VOLUMUL SFERELOR INREGISTRARE ESTE DE : " << volt << "cm3" << std::endl;
}
I created a new project in c++ but i keep getting the same error
Main.cpp
#include <iostream>
#include <string.h>
#include "Computer.cpp"
#include "Computer.h"
using namespace std;
int main()
{
cout << "Hello World!" << endl;
return 0;
}
Computer.h
#ifndef COMPUTER_H_INCLUDED
#define COMPUTER_H_INCLUDED
#include <string>
class Computer
{
public:
std::string marca;
float prezzo;
bool acceso;
Computer();
void Accenditi();
void Spegniti();
void ImpostaMarca(std::string m);
void ImpostaPrezzo(float p);
};
#endif
Computer.cpp
#include "Computer.h"
Computer::Computer()
{
}
void Computer::Accenditi()
{
if(!acceso)
{
acceso = true;
}
else
{
std::cout << "Sono già acceso";
}
}
void Computer::Spegniti()
{
if(acceso)
{
acceso = false;
}
else
{
std::cout << "Sono già spento";
}
}
void Computer::ImpostaMarca(std::string m)
{
marca = m;
}
void Computer::ImpostaPrezzo(float p)
{
prezzo = p;
}
The Problem
i don't understand what's wrong with Computer.cpp, i keep getting "cout is not a member of std". I tryed to add "using namespace std" and i also tryed to add the library #include but i get a new file called "makefile.win". How can i fix this error ?
You need to include iostream header in your Computer.cpp file as such:
include <iostream>
and to make your life easier, you can also add:
using std::cout;
using std::endl;
right at the bottom of your include, that way you don't have to keep adding "std::cout" everytime, you can just use "cout"
Also want to add:
You can remove the include computer.cpp from your main.cpp and just leave the header. The C++ linker will automatically link your computer.h and computer.cpp together since .cpp includes the header, and your main includes the computer.h
Add # include <iostream> at the files that you use std::cout and std::cin.
This question already has answers here:
Resolve build errors due to circular dependency amongst classes
(12 answers)
Closed 7 years ago.
Please see my previous post here:
Undefined type error even with forward declaration
I moved the definitions to cpp files and I still face the issue. Any ideas why? My files look like this:
Header1.hpp
#ifndef HEADER1_HPP
#define HEADER1_HPP
namespace sample_ns
{
class sample_class{
public:
static int getNumber();
static void print();
};
}
#endif
Header2.hpp
#ifndef HEADER2_HPP
#define HEADER2_HPP
namespace sample_ns
{
class sample_class2{
public:
sample_class2();
int getNumber2();
};
}
#endif
Source1.cpp
#include "Header1.hpp"
#include "Header2.hpp"
#include "stdafx.h"
#include <iostream>
namespace sample_ns
{
int sample_class::getNumber()
{
sample_class2 obj;
return obj.getNumber2();
}
void sample_class::print()
{
std::cout << "Print utility function" << std::endl;
}
}
Source2.cpp
#include "Header2.hpp"
#include "Header1.hpp"
#include "stdafx.h"
#include <iostream>
namespace sample_ns
{
sample_class2::sample_class2()
{
sample_class::print();
}
int sample_class2::getNumber2()
{
sample_class::print();
return 5;
}
}
In my main I call it as:
std::cout << sample_ns::sample_class::getNumber() << std::endl;
I get 'sample_class2' : undeclared identifier. I tried adding class sample_class2; but that still gives me error
EDIT:
my main file:
#include "stdafx.h"
#include <iostream>
#include "Header1.hpp"
int _tmain(int argc, _TCHAR* argv[])
{
std::cout << "hello" << std::endl;
std::cout << sample_ns::sample_class::getNumber() << std::endl;
return 0;
}
The best practice for declaring classes and namespaces in header and cpp files is using structure likes below:
Header1.hpp
#ifndef HEADER1_HPP
#define HEADER1_HPP
#include "Header2.hpp"
#include <iostream>
namespace sample_ns
{
class sample_class{
public:
static int getNumber();
static void print();
};
}
#endif
Source1.cpp
#include "Header1.hpp"
namespace sample_ns
{
int sample_class::getNumber()
{
sample_class2 obj;
return obj.getNumber2();
}
void sample_class::print()
{
std::cout << "Print utility function" << std::endl;
}
}
So by including in header files and using ifndef you become sure that circular dependencies will not occure.
I am having a very unusual problem:
I keep getting multiple definition of functions in my class.
This is my main .cpp
#include <iostream>
#include "Calculation.cpp"
using namespace std;
int main()
{
cout << "Hello world!" << endl;
return 0;
}
this is my class .h
#ifndef CALCULATION_H_INCLUDED
#define CALCULATION_H_INCLUDED
class Calculation
{
public:
Calculation();
private:
};
#endif // CALCULATION_H_INCLUDED
this is my implementation file .cpp
#include "Calculation.h"
Calculation::Calculation()
{
}
Please help me; I have tried to create a new project but that didn't help.
All help is appreciated.
make your main.cpp like :
#include <iostream>
#include "Calculation.h" // not Calculation.cpp
using namespace std;
int main()
{
cout << "Hello world!" << endl;
return 0;
}
You have to include your Calculation.h in th main.cpp and you have to compile it as follows,
g++ main.cpp Calculate.cpp -o main -I<path for your .h file>
main.cpp
#include<iostream>
#include "Calculation.h"
//using namespace std; // Avoid this, always to use std::cout .. etc on place
int main()
{
Calculation c; //Creating the object of Calculation class
std::cout<<"Hello World!"<<std::endl;
return 0;
}