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Can you explain this very simple code to me.

Posted on 2011-02-20
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Last Modified: 2012-05-11
I have started learning C++ so can someone explain the following two versions of code in the simplest way.


n a m e s p a c e S t a c k {
v o i d p u s h (c h a r );
c h a r p o p ();
}

v o i d f ()
{
S t a c k :: p u s h (´c ´);
i f (S t a c k :: p o p () != ´c ´) e r r o r ("i m p o s s i b l e ");
}

n a m e s p a c e S t a c k {
c o n s t  i n t  m a x _ s i z e = 2 0 0 ;
c h a r  v [m a x _ s i z e ];
i n t  t o p = 0 ;
v o i d  p u s h (c h a r c )

c h a r p o p () }



Another version of the same code but whats the difference??

n a m e s p a c e S t a c k
 {
v o i d p u s h (c h a r );
c h a r p o p ();
}

#i n c l u d e "s t a c k .h " 
v o i d f ()
{
S t a c k :: p u s h (´c ´);
i f (S t a c k :: p o p () != ´c ´) e r r o r ("i m p o s s i b l e ");
}

#i n c l u d e "s t a c k .h "
n a m e s p a c e S t a c k {
c o n s t  i n t  m a x _ s i z e = 2 0 0 ;
c h a r v [m a x _ s i z e ];
i n t  t o p = 0 ;
}
v o i d S t a c k :: p u s h (c h a r c )
c h a r S t a c k :: p o p ()
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Question by:Osloiite
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2 Comments
 
LVL 13

Accepted Solution

by:
F Igor earned 50 total points
ID: 34936677
The first version is a "one file" program for a "stack" example,
while the second version is the same program in a modular "multi file" program.
(to demonstrate the use of #include)

The second version more explicit:

//File named "stack.h" (defines the Stack namespace)

namespace Stack
 {
void push (char );
char pop();
}


//Another file using the stack.h file (uses the Stack namespace to call their functions)

#include "stack.h"

void f()
{
Stack::push(´c´);
if (Stack::pop() != ´c´) error ("impossible");
}


//Another file using the stack.h file
(adds some properties to namespace Stack)

#include "stack.h"
namespace Stack {
const  int max_size = 200;
char v[max_size];
int  top = 0 ;
}
void Stack::push (char c )
char Stack::pop()





Note the use of Stack::push() or Stack::pop() when the call it's out of the namespace
(second example) and calling directly to push() and pop() when it's within the namespace.

namespace Stack {
const  int max_size = 200;
char v[max_size];
int  top = 0 ;
}
void Stack::push (char c )
char Stack::pop()


namespace Stack {
const  int max_size = 200;
char v[max_size];
int  top = 0 ;
void push (char c )
char pop()
}
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Expert Comment

by:DeepuAbrahamK
ID: 34958191
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