Interview question.

SATYAN JANA's Avatar
Light Poster
A good question usually asked at interviews,-

/**************************/
int * func(int, int);
void main()
{
int *ptr = func(2,3);
printf("\nHello World!\n");
printf("\n%d\n",*ptr);
}
int * func(int i, int j)
{
int k = i + j;
return &k;
}
/**************************/
What will be the output of the above program?
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Here is the output,-
Hello World!
Garbage Value

Note that Garbage Value will be printed here instead of 5. This is because once the control returns from func() to the main(), the address of local variable 'k' is free. So the contents of this address can be modified by anybody else.
0
shabbir's Avatar, Join Date: Jul 2004
Go4Expert Founder
Quote:
Originally Posted by SATYAN JANA
A good question usually asked at interviews
I will add one more here
Code:
void AllocateMem(int *p)
{
  p = (int*)malloc(sizeof(int));
  *p = 6;
  return;
}

void main()
{
  int *a;
  AllocateMem(&a); 
  printf("[%d]",*a);
}
Gives an exception. I want the function to allocate the memory and want that to use in main. How?
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Code:
void AllocateMemory(int **p)
{
  *p = (int*)malloc(sizeof(int));
  **p = 6;
  return;
}

void main()
{
  int *a;
  AllocateMemory(&a);
  printf("[%d]",*a);
}
0
coderzone's Avatar, Join Date: Jul 2004
Team Leader
I will add one
Code:
class A
{
private:
  int a;
public:
  void func(void);
};

class B
{
private:
  int a;
public:
  virtual void func(void);
};

int main()
{
  A a;
  B b;
  cout<<sizeof(a)<<"  "<<sizeof(b)<<endl;
}
What will be the output of the above program and why?
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2 4 because there is a Pointer to the virtual table to resolve the dynamic binding of the virtual function.
0
go4expert's Avatar, Join Date: Aug 2004
Team Leader
Some multiple choice questions in C/C++ thread will add to the current questions.