main()

{

char s[ ] = "man";

int i;

for( i=0; s[ i ]; i++)

printf( "n%c%c%c%c", s[ i ], *(s+i), *(i+s), i[s] );

}

#include "mem.h"

#include "alloc.h"

main()

{

      int area;

      char *dest;

      char src[] = "Life is the camera and you are the target"

                                  "so keep smiling always";

      area = sizeof (src);

      dest = malloc (area);

      memmove (dest, src, area);

      printf("\n%s", dest);

      printf("\n%s",src);

}

#include "string.h"

#include "stdlib.h"

struct stud

{

       int rollno;

       int marks;

       char name[30];

};

int sort_m (struct stud *, struct stud *);

int sort_name (struct stud *, struct stud *);

int sort_marks (struct stud *, struct stud *);

main()

{

static struct stud ss[] = {

                                            { 15, 96, "Akshay" },

                                            { 2, 97, "Madhuri" },

                                            { 8, 85, "Aishvarya" },

                                            { 10, 80, "Sushmita" }

                                   };

int x,w;

clrscr();

w = sizeof (struct stud);

printf ('\nIn order of roll numbers:");

qsort (ss, 4, w, sort_rn);

for(x=0; x<4;x++)

     printf ("\n%d%s%d", ss[x].rollno, ss[x].name,ss[x].marks);

printf("\n\nIn order of names:");

qsort(ss, 4, sort_name);

for (x=0; x<4;x++)

      printf("\n%d%s%d",ss[x].rollno, ss[x].name,ss[x].marks);

printf("\n\nIn order of marks:");

qsort(ss,4,w,sort_marks);

for (x=0;x<4;x++)

      printf ("\n%d%s%d",ss[x].rollno,ss[x].name,ss[x].marks);

}

int sort_rn (struct stud *t1, struct stud *t2)

{

     return (t1->rollno-t2->rollno);

}

int sort_name (struct stud *t1, struct stud *t2)

{

     return (strcmp(t1->name,t2->name));

}

int sort_marks (struct stud *t1, struct stud *t2)

{

     return (t2->marks-t1->marks);

}

atoi()         Converts a string to an integer.

itoa()         Convert an integer to a string

gcvt()        Converts a floating-point number to a string

#include "stdlib.h"

main()

{

      char s[] = "12345";

      char buffer [15], string[20];

      int i;

      i = atoi (s);

      printf("\n%d",i);

       gcvt (20.141672, 4, buffer);

       printf ("\n%s", buffer);

       itoa(15, string,2);

        printf ("\n%s", string);

}

4  4  2

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.

While extracting a float argument using va_arg we should have useed 

c = va_arg (ptr, double)

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 ));

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 */

             }

      }

}