How access global function in class which is having same function signature as global function?

Question

Following is my scenario:

file.h This file contains two function with extern

extern int add(int a, int b);
extern int sub(int a, int b);

file.cpp Implementation of above functions.

int add(int a, int b)
{
    return 20;
}

int sun(int a, int b)
{
    return 20;
}

test.h This is class test in which two member function with same signature as extern add and sub in file.h

class test
{
    public:
          test();
          ~test();
    private:
         int add(int a, int b);
         int sub(int a, int b);
}

test.cpp Implementation of test class in test class constructor add function is called as well as both file are included.

#include "test.h"
#include "file.h" // Contains extern methods
#include <iostream>

test::test()
{
     int addition = add(10, 10);
     printf("Addition: %d ", addition );
}

int 
test::add(int a, int b)
{
    return 10;
}

int 
test::sub(int a, int b)
{
    return 10;
}

main.cpp

 #include "test.h"
 int main()
 {
   test *a = new test();
 }

Now my question is in main class what will be printed. Whether it will print

it giving output as Addition : 10 Why it is giving 10 ? Is class test uses its own function add() and sub(). Because both function are present in file.h and same class. My guess was it will give ambiguity for functions. Is there any standard if so please explain. And how can i use functions from file.h in class test.

Obviously a compile error since you're trying to assign a pointer type to a non-pointer type here: `test a = new test();` — greatwolf, Feb 10 '15 at 12:26
Nothing will get printed. Even if it compiled, you're not executing anything that prints anything. Just correct, compile and execute it. — rubikonx9, Feb 10 '15 at 12:27
The odds are pretty good that compiling the program and running it will provide an answer. — molbdnilo, Feb 10 '15 at 12:30
Why are you asking what the compiler will do, instead of compiling it yourself? If you don't have one on hand, there are [{online}](http://coliru.stacked-crooked.com/) [{ones}](http://ideone.com/). — Angew is no longer proud of SO, Feb 10 '15 at 12:31
actually i want to ask question like this but in hurry i had posted partial question and got so may downvote :( please check updated question. — DigviJay Patil, Feb 10 '15 at 12:47
@zenith yes it got it can you just post your comment in answer so that i can accept it as answer and cad upvote your answer — DigviJay Patil, Feb 10 '15 at 12:59

score 1 · Accepted Answer · edited May 23 '17 at 10:33

1

Calling add inside the test class will use the add member function.

To call the global add function use the global scope resolution operator :::

int addition = ::add(10, 10);

edited May 23 '17 at 10:33

Community

1
1

answered Feb 10 '15 at 13:02

Emil Laine

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thank you ! can you send me the link where i can get documentation of this. – DigviJay Patil Feb 10 '15 at 13:05
1

@D'JayPatil Grab a [good book](http://stackoverflow.com/q/388242/1782465) and read it. The behaviour is described in the C++ standard, but most mortals don't want to read *that.* – Angew is no longer proud of SO Feb 10 '15 at 13:07
@D'JayPatil Couldn't find an official doc but added a link to an SO question to my answer. – Emil Laine Feb 10 '15 at 13:10

score 1 · Answer 2 · answered Feb 10 '15 at 13:21

use can also do it using namespace. in file.h

#include "file.h"
namespace file
{
     int add(int a, int b)
     {
         return 20;
     }

     int sub(int a, int b)
     {
         return 20;
     }
}

in test.cpp

#include "test.h"
#include "file.h" 
#include <iostream>

test::test()
{
     int addition = file::add(10, 10); // used namespace here
     printf("Addition: %d ", addition );
}

int 
test::add(int a, int b)
{
    return 10;
}

int 
test::sub(int a, int b)
{
    return 10;
}

using namespace i can i have multiple functions with same signature. right Uday — DigviJay Patil, Feb 10 '15 at 13:27

How access global function in class which is having same function signature as global function?

2 Answers2