The C Programming Language Question To Exercises with Answer

1) main()

{

extern int i;

{

                  int i=20;

{

  const volatile unsigned i=30; printf("%d",i); 

}

  printf("%d",i);

}

   printf("%d",i);

}

int i;

2) Printf can be implemented by using  __________ list.

Answer: 

Variable length argument lists

3) char *someFun()

{

char *temp = “string constant";

return temp;

}

int main()

{

puts(someFun());

}

Answer:

string constant 

Explanation:

The program suffers no problem and gives the output correctly because the character constants are stored in code/data area and not allocated in stack, so this doesn’t lead to dangling pointers. 

4) char *someFun1()

{

char temp[ ] = “string";

return temp;

}

char *someFun2()

{

char temp[ ] = {‘s’, ‘t’,’r’,’i’,’n’,’g’};

return temp;

}

int main()

{

puts(someFun1());

puts(someFun2());

}

Answer:

Garbage values.

Explanation:

Both the functions suffer from the problem of dangling pointers. In someFun1() temp is a character array and so the space for it is allocated in heap and is initialized with character string “string”. This is created dynamically as the function is called, so is also deleted dynamically on exiting the function so the string data is not available in the calling function main() leading to print some garbage values. The function someFun2() also suffers from the same problem but the problem can be easily identified in this case.