Interview Question


Country: United States




Comment hidden because of low score. Click to expand.
1
of 1 vote

My thought is to use a function pointer (that is, a callback) in place of an abstract class.

Take a polymorphic validator, for instance. It might be a PDF validator or a text validator, etc. But, the client code only knows the abstract version until runtime.

// OOP version
// validate a document - it might be text, pdf or whatever
public void readFile(String filename, AbstractValidator v) {

        // morphs into the specific validator at runtime
	if (v.validate(filename) == false)
		return;

       // do more stuff
}

/* C version */

void readFile(char *filename, int (*validate)(char*)) {

        /* morphs at runtime */
	if (validate(filename) == 0)
		return;
      
	/* do stuff */
}

- Michael.J.Keating April 23, 2014 | Flag Reply
Comment hidden because of low score. Click to expand.
0
of 0 vote

Polymophism is the capability to change the behavior of a data type/structure. The easiest way is just to provide pointers to functions and allow for modification of the pointers. Override the pointers and point to a new function. Technically all C++ functions pass the data class as a parameter.
i..e

struct ChangeData
{
int data1;
};

typedef int (*CHANGE_ME)(ChangeData * param1);

int DefaultFn(ChangeData * param1) { return 0; }

CHANGE_ME &PtrChangeData = (CHANGE_ME)&DefaultFn;

- ntf January 06, 2015 | Flag Reply
Comment hidden because of low score. Click to expand.
-2
of 2 vote

Write a C++ compiler in C. LOL.

- Anonymous April 23, 2014 | Flag Reply


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