Question

how do you make a class if you have a 3 files, sample.h which has a class type, and then sample.cpp which has all the functions, somehow it works when i put into a one file but doesn't when i try to compile together with 3 files.

Answer 1

for example: lets say i have def.h
class def{
void something()
}
then i have a def.cpp:
void def::something()
bla bla bla....

but it doesn't work

Answer 2

thats pretty much what i have and it works using one file:
http://liveworkspace.org/code/c898c672ff8f77414b93334e1b7ae71c
but when i separate it into 3 files, from line 1 to 16 make a stack.h and from line 17 to 37 to stack.cpp and the rest in main.cpp it gives me a lot of errors

Answer 3

the names of the files must be identical, i.e add.h, add.cpp e.t.c

Answer 4

it is...

Answer 5

im sure ur code has a slight mistake just recheck it again,

Answer 6

In your def.cpp, did you #include "def.h" ?

Answer 7

yes i did

Answer 8

Did you also include them in your main.cpp?

Answer 9

yes

Answer 10

Did you use #ifndef in the header file to be sure not to redefine your class? Because outside of some more explicit details I'm afraid it is really just a guessing game at this point.

Answer 11

Post the three files, the error messages and the compile command.

Answer 12

You need to call 'void something()' as public. Because a class automatically makes it private if you haven't defined it to public. Here is an example:

class def{
public:
void something()
}

And then you will be able to call "void def::something()"

Answer 13

i have assigned it to public

Answer 14

thats my make file:

run: stack.o main.o
g++ $(FLAGS) -o run stack.o main.o
stack.o: stack.cpp stack.h
g++ $(FLAGS) -c stack.cpp
main.o: main.cpp stack.h
g++ $(FLAGS) -c main.cpp
clean:
rm -f run *.o

Answer 15

Mind posting the error message, so we at least know what is not working? ^^

Answer 16

a lot of things

Answer 17

g++ -c stack.cpp
In file included from stack.cpp:2:
stack.h:11: error: expected initializer before ‘*’ token
stack.h:14: error: ‘Stack’ has not been declared
stack.h:15: error: ‘Stack’ has not been declared
stack.h:16: error: ‘Stack’ has not been declared
stack.h:17: error: ‘Stack’ has not been declared
stack.cpp:3: error: variable or field ‘push’ declared void
stack.cpp:3: error: ‘Stack’ was not declared in this scope
stack.cpp:3: error: ‘pstack’ was not declared in this scope
stack.cpp:3: error: expected primary-expression before ‘x’
stack.cpp:11: error: ‘std::string Stack2::top’ is not a static member of ‘class Stack2’
stack.cpp:11: error: ‘Stack’ was not declared in this scope
stack.cpp:11: error: ‘stack’ was not declared in this scope
stack.cpp:11: error: expected ‘,’ or ‘;’ before ‘{’ token
stack.cpp:14: error: ‘bool Stack2::is_empty’ is not a static member of ‘class Stack2’
stack.cpp:14: error: ‘Stack’ was not declared in this scope
stack.cpp:14: error: expected ‘,’ or ‘;’ before ‘{’ token
stack.cpp:17: error: variable or field ‘pop’ declared void
stack.cpp:17: error: ‘Stack’ was not declared in this scope
stack.cpp:17: error: ‘stack’ was not declared in this scope
make: *** [stack.o] Error 1

Answer 18

i don't know why i get so much errors when it works correctly in one file

Answer 19

Can you give us the codes? So we can see what you did wrong

Answer 20

one sec

Answer 21

//file: stack.h
#include <iostream>
using namespace std;
#ifndef STACK_H
#define STACK_H
struct Node {
string x;
Node *next;
}
typedef Node* Stack;
class Stack2{
public:
void push(Stack* pstack, string);
void pop(Stack& stack);
string top(Stack& stack);
bool is_empty(Stack stack);
};
#endif

Answer 22

//file: stack.cpp
#include "stack.h"
void Stack2::push(Stack* pstack, string x){
Node* t;
t=new Node;
t->x=x;
t->next=*pstack;
*pstack=t;
return;
}
string Stack2::top(Stack& stack){
return stack->x;
}
bool Stack2::is_empty(Stack stack){
stack= NULL;
}
void Stack2::pop(Stack& stack){
Node* p;
p=new Node;
p=stack->next;
stack=p;
return;
}


//file: main.cpp
#include <iostream>
#include "stack.h"
#include <vector>
#include <string>
using namespace std;
int main(){
size_t i;
Stack2 Stack2;
Stack stack = 0;
string arr[]= {"1","2","3","4"};
vector<string> x(arr, arr +4);
cout<<"Original string vector \n";
for (i=0; i<x.size(); i++){
cout<<x[i]<<", ";}
cout<<endl;
for (i=0; i<x.size(); i++){
Stack2.push(&stack,x[i]);}
cout<<"After using the stack to hold the string in reverse order we get: \n"\
;
Node* p;
p=stack;
while (p !=0){
cout<<p->x<<", ";
p=p->next;
}
cout<<endl;

cout<<"After we use top() we get: \n";
cout<<Stack2.top(stack)<<endl;
cout<<"After we use pop() we get: \n";
Stack2.pop(stack);
Node* w;
w=stack;
while (w !=0){
cout<<w->x<<", ";
w=w->next;
}
cout<<endl;
}

Answer 23

Why do you have what appears to be a handle, typedef after the struct? typedef Node* Stack;

Answer 24

where should i put it then?

Answer 25

When programming in C I usually do it like this:
typedef struct Node {
string x;
Node *next; // not sure you can create a new object inside the definition
} Stack_t;

Answer 26

i don't think thats the problem, because why does it work in one file?

Answer 27

that still doesn't work

Answer 28

waittt it works

Answer 29

That is where the first error in your log is pointing, error: expected initializer before ‘*’ token
The second is pointing here: void pop(Stack& stack); saying that stack is undefined.

Answer 30

i just put ; after }
struct Node {
string x;
Node *next;
}

Answer 31

Well good, one down, 20 to go. :)

Answer 32

that actually fixed everything :) lol

Answer 33

Excellent

Answer 34

Indeed

Answer 35

now i have to put this into a template class

Answer 36

lol

Answer 37

Good luck.

Answer 38

Just a question tho, why are you using both class and struct? Isn't it easier to just use one instead of both? ^^

And also, put the ifndef and define at the very top of the file, and then everything else. so it looks like this:

#ifndef _STACK_H_
#define _STACK_H_

#include <iostream>
using namespace std;

Answer 39

can we use class to define node or what?

Answer 40

how would you change this into a template as im really confused now, I know we should declare template<class W> but what then I can change to W