C++ Programming - OOPS Concepts - Discussion

Discussion Forum : OOPS Concepts - General Questions (Q.No. 31)
31.
Which of the following is the correct way of declaring a function as constant?
const int ShowData(void) { /* statements */ }
int const ShowData(void) { /* statements */ }
int ShowData(void) const { /* statements */ }
Both A and B
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
13 comments Page 1 of 2.

Dimpi said:   6 months ago
D option is the right one.

Because both A and B options correctly define the function, it returns a const int.

Amit Shahi said:   8 months ago
Here the question is how to declare the function as a constant that's why the C option is the right answer.

If the question is asking how to declare a function return as a constant then the D option is the right answer.

Vls said:   2 years ago
Here, It asks about a function, not a member function or method. Constness of a standalone function doesn't make sense.

Sai Aditya said:   4 years ago
I think option D is the right one.

Waqar Akram said:   5 years ago
Option C is Correct.
Example of Deepak Kumar is 100% correct.

Chuck N said:   7 years ago
Exampe C is correct.

Examples A and B compile,but it seems the const keyword is just ignored, the function does NOT actually work as const. Below is a different example I found elsewhere. Since non-const functions can only be called by non-const objects, the below example will only compile if the function getValue is declared as in the example C.


If declared as in examples A and B, you will get a compiler error. The compiler error will go away if " Test t" in Main is not declared as a const, BUT the compiler is just ignoring the const keyword and the function is NOT const in these cases.

#include <iostream>
using namespace std;

class Test {
int value;
public:
Test(int v = 0) {value = v;}
int getValue() const {return value;}
};

int main() {
const Test t;
cout << t.getValue();
return 0;
}
(1)

Sudeshna cnaudhuri said:   8 years ago
C is the wrong option. I checked it by running a program in Dev c++.

Both A and B works. D is the correct one.

Govind kawde said:   8 years ago
Yes, I too think option D is Correct.

Navnath Dombale said:   1 decade ago
During object creation is there need to write const keyword like const date bdate();

Nazmul said:   1 decade ago
Is this ok that a const object can refer to/call only a const function?


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