c++, Connecting Hpp and Cpp [closed] - c++

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/*Header.h file*/
#include <iostream>
using namespace std;
int main(){
/*Menu*/
/*case1:
int x;
cout << "Input ammount:";
cin >> x
sugarcake(x)*/
/*case2:
something else
*/
}
/*sugarcake.cpp file*/
#include <iostream>
#include "Header.h"
using namespace std;
void sugarcake(int x) {
cout << (x * 0.75) << "st egg" << endl;
cout << (x * 0.75) << "dl sugar" << endl;
cout << (x * 0.5) << "tsk vanillasugar" << endl;
cout << (x * 0.5) << "tsk blabla" << endl;
cout << (x * 0.75) << "dl wheatflour" << endl;
cout << (x * 18.75) << "gram butter" << endl;
cout << (x * 0.25) << "dl water" << endl;
}
How do i make this work or have i understood it completely wrong? (Started out with C++ yesterday so please be kind and i haven't been able to find any clear answer that works for me elsewhere)
TL DR: Call the function sugarcake(int x) in sugarcake.cpp inside the Header.h

Answer 1

You should not put code in the header file, instead use two source (.cpp) files, and let the header file only contain a declaration of (in your case) the sugarcake function.
So the header file should look something like
// These first two line (and the last line of the file) is part of
// a header include guard (see https://en.wikipedia.org/wiki/Include_guard)
#ifndef HEADER_H
#define HEADER_H
void sugarcake(int x);
#endif // HEADER_H
The sugarcake.cpp file:
#include <iostream>
#include "header.h" // Technically we don't need to include the header
// file here, but it's always a good idea to do
// anyway
void sugarcake(int x) {
...
}
And finally the main.cpp file:
#include <iostream>
#include "header.h"
int main() {
int x;
std::cin >> x;
sugarcake(x);
}
How to build this depends on your environment, but if you're using GCC from the command line then you do like this
$ g++ -Wall -Wextra main.cpp sugarcake.cpp -o sugarcake
The -Wall and -Wextra options are to enable extra warnings, always a good idea. The -o options tells g++ what to name the executable program it creates. The two source files are the files you just created.

Answer 2

We use header files to describe functions which will be used after in another occasion per say.
So I will show how I organize my functions in the header files:
/* header.h
* include guards below, it is very import to use it to be sure you'r not
* including things twice.
*/
#ifndef HEADER_H
#define HEADER_H
// I write function prototypes in the header files.
int sum(int &a, int &b);
#endif // HEADER_H
The definition of the function is written in the header.cpp
// header.cpp
#include "header.h"
int sum(int &a, int &b)
{
int total = a + b;
return total;
}
To use that function in main.cpp you just have to include the header.cpp
// main.cpp
#include <iostream>
#include "header.h"
int main(int argc, char *argv[])
{
int a = 5;
int b = 4;
int total = sum(a, b);
std::cout << "The total sum of the 4 and 5 numbers is: " << total << std::endl;
}
See how it is made? Then you can compile the cpp files and it will work!