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Q:

What would be the output of the following program?

main()

{

        char huge * near * far *ptr1;

        char near * far * huge *ptr2;

        char far * huge * near *ptr3;

         printf ("%d%d%d", sizeof (ptr1), sizeof (ptr2), sizeof (ptr3));

}

Answer

4  4  2

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Subject: Programming

Q:

If I use the following printf() to print a long int why I am not warned about the type mismatch?

printf ("%d",num );

Answer

When a function accepts a variable number of arguments , its prototype cannot provide any information about the number of arguments and type of those variable arguments. Hence the compiler cannot warn about the mismatches. The programmer must make sure that arguments match or must manually insert explicit typecast.

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Subject: Programming

Q:

Point out the error, if any, in the following program.

#include "stdarg.h"

main()

{

     display ( 4, 12.5, 13.5, 14.5, 44.3);

}

display(int num, ...)

{

       float c; int j;

        va_list ptr;

        va_start (ptr, num);

        for ( j = 1; j <= num; j++)

        {

            c = va_arg ( ptr, float );

            printf ("\n%f", c);

         }

}

Answer

While extracting a float argument using va_arg we should have useed 


c = va_arg (ptr, double)

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Subject: Programming

Q:

What is the difference between malloc() and calloc() functions?

Answer

As against malloc(), calloc() needs two arguments, the number of elements  to be allocated and the size of each element. For example,


 p = (int *) calloc (10, sizeof (int));


would allocate space for a 10- integer array. Additionally, calloc() would also set each of this element with a value 0.


Thus the above call to calloc() is equivalent to:


p = (int *) malloc (10 * sizeof (int));


memset (p, 0, 10 * sizeof( int ));

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Subject: Programming

Q:

Can I increase the size of a dynamically allocated array? < Yes / No> if yes, how?

Answer

Yes, using the realloc() function as shown below:


main()


{


        int *p;


        p = ( int *) malloc (20) ;


        t = p;


        t = (int *) realloc ( p, 40);


        if ( t == NULL )


        Printf (" Cannot reallocate, leaves previous allocated region unchanged ");


       else


       {


              if ( p ==t )


              ;  / * the array expanded at the same region */


             else


            { 


                 free ( p ); / * deallocate the original array */


                 p = t;  /* set p to newly allocated region */


             }


      }


}  

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Subject: Programming

Q:

How would you free the memory allocated by the following program?

#include "alloc.h"

#define MAXROW 3

#define MAXCOL 4

main()

{

     int **p, i;

     p = (int **) malloc (MAXROW * sizeof (int *));

      for ( i = 0; i < MAXROW ; i++)

            p[i] = (int *) malloc (MAXCOL * sizeof (int ));

}

Answer

for ( i=0; i < MAXROW ; i++)


free (p[i]);


free (p);

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Subject: Programming

Q:

What would be the output of the following program ?

main()

{

     const int x = 5; 

      int *ptrx;

      ptrx = &x;

      *ptr = 10;

       printf ("%d", x);

}

A) 5 B) 10
C) Error D) Garbage value
 
Answer & Explanation Answer: B) 10

Explanation:
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Filed Under: Programming

Q:

Point out the error in the following program.

main()

{

    char mybuf[] = "Zanzibar" ;

    char yourbuf[] = " Zienckewiz";

    char * const ptr = mybuf;

     *ptr = 'a';

     ptr = yourbuf;

}

Answer

ptr pointer is constant. In ptr = yourbuf the program is trying to modify it, hence an error.

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Subject: Programming