Programming Questions

The coding or scrambling of data so that humans cannot read them is known as encryption.

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 ));

#include<stdio.h>

int main(){

  int a[10][10],i,j,sum=0,m,n;

  printf("\nEnter the row and column of matrix: ");
  scanf("%d %d",&m,&n);

  printf("\nEnter the elements of matrix: ");
  for(i=0;i<m;i++)
      for(j=0;j<n;j++)
           scanf("%d",&a[i][j]);
  printf("\nThe matrix is\n");

  for(i=0;i<m;i++){
      printf("\n");
      for(j=0;j<m;j++){
      printf("%d\t",a[i][j]);
      }
 }
 for(i=0;i<m;i++){
     for(j=0;j<n;j++){
          if(i==j)
              sum=sum+a[i][j];
     }
 }
 printf("\n\nSum of the diagonal elements of a matrix is: %d",sum);

 return 0;
}

Sample output:

Enter the row and column of matrix: 3 3
Enter the elements of matrix:
2
3
5
6
7
9
2
6
7
The matrix is
2       3       5
6       7       9
2       6       7
Sum of the diagonal elements of a matrix is: 16

#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);

}

4  4  2

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

free (p[i]);

free (p);