A reference variable provides an alias to a previously defined variable.
Data -type & reference-name = variable name

A destructor is automatically called when the object is destroyed. A virtual destructor in C++ is used primarily to prevent resource leaks by performing a clean-up of the object.

All the features of C are similiar to C++ except some features, such as polymorphism, operator overloading which are supported in C++ but not in C language.

Both C and C++ language is similiar in their functionality but C++ provides with more tools and options.

#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 <stdio.h>

int main() {

  int a[5][5], b[5][5], c[5][5], i, j, k, sum = 0, m, n, o, p;

  printf( "\nEnter the row and column of first matrix" );

  scanf( "%d %d", &m, &n );

  printf( "\nEnter the row and column of second matrix" );

  scanf( "%d %d", &o, &p );

  if(n!=o) {

      printf( "Matrix mutiplication is not possible" );

      printf( "\nColumn of first matrix must be same as row of second matrix" );

  }

  else {

      printf( "\nEnter the First matrix" );

      for( i=0; i<m; i++ )

      for( j=0; j<n; j++ )

           scanf( "%d", &a[i][j] );

      printf( "\nEnter the Second matrix" );

      for( i=0; i<o; i++ )

      for( j=0; j<p; j++ )

           scanf( "%d", &b[i][j] );

      printf( "\nThe First matrix is\n" );

      for( i=0; i<m; i++ ) {

      printf("\n");

      for( j=0; j<n; j++ ) {

           printf( "%d\t", a[i][j] );

      }

      }

      printf( "\nThe Second matrix is\n" );

      for( i=0; i<o; i++ ) {

      printf("\n");

      for( j=0; j<p; j++ ) {

           printf( "%d\t", b[i][j] );

      }       

      }

      for( i=0; i<m; i++ )

      for( j=0; j<p;j++ )

           c[i][j] = 0;

      for( i=0; i<m; i++ ) { //row of first matrix

      for( j=0; j<p; j++ )  {  //column of second matrix

           sum = 0;

           for( k=0; k<n; k++ )

               sum = sum + a[i][k]*b[k][j];

           c[i][j] = sum;

      }

      }

  }

  printf( "\nThe multiplication of two matrix is\n" );

  for( i=0; i<m; i++ ) {

      printf("\n");

      for( j=0; j<p; j++ ) {

           printf( "%d\t", c[i][j] );

      }

  }

  return 0;

}

#include<stdio.h>
int main(){

  int s,temp,i,j,a[20];

  printf("Enter total numbers of elements: ");
  scanf("%d",&s);

  printf("Enter %d elements: ",s);
  for(i=0;i<s;i++)
      scanf("%d",&a[i]);

  //Bubble sorting algorithm
  for(i=s-2;i>=0;i--){
      for(j=0;j<=i;j++){
           if(a[j]>a[j+1]){
               temp=a[j];
              a[j]=a[j+1];
              a[j+1]=temp;
           }
      }
  }

  printf("After sorting: ");
  for(i=0;i<s;i++)
      printf(" %d",a[i]);

  return 0;
}

#include<stdio.h>

void quicksort(int [10],int,int);

int main(){
  int x[20],size,i;

  printf("Enter size of the array: ");
  scanf("%d",&size);

  printf("Enter %d elements: ",size);
  for(i=0;i<size;i++)
    scanf("%d",&x[i]);

  quicksort(x,0,size-1);

  printf("Sorted elements: ");
  for(i=0;i<size;i++)
    printf(" %d",x[i]);

  return 0;
}

void quicksort(int x[10],int first,int last){
    int pivot,j,temp,i;

     if(first<last){
         pivot=first;
         i=first;
         j=last;

         while(i<j){
             while(x[i]<=x[pivot]&&i<last)
                 i++;
             while(x[j]>x[pivot])
                 j--;
             if(i<j){
                 temp=x[i];
                  x[i]=x[j];
                  x[j]=temp;
             }
         }

         temp=x[pivot];
         x[pivot]=x[j];
         x[j]=temp;
         quicksort(x,first,j-1);
         quicksort(x,j+1,last);

    }
}

Output:
Enter size of the array: 5
Enter 5 elements: 3 8 0 1 2
Sorted elements: 0 1 2 3 8

 #include<stdio.h>
int main(){
  int r,i,j,k;
  printf("Enter the number range: ");
  scanf("%d",&r);
  for(i=1;i<=r;i++){
      for(j=1;j<=10;j++)
           printf("%d*%d=%d ",i,j,i*j);
      printf("\n");
  }
  return 0;
}

Sample Output:
Enter the number range: 5

1*1=1 1*2=2 1*3=3 1*4=4 1*5=5 1*6=6 1*7=7 1*8=8 1*9=9 1*10=10
2*1=2 2*2=4 2*3=6 2*4=8 2*5=10 2*6=12 2*7=14 2*8=16 2*9=18 2*10=20
3*1=3 3*2=6 3*3=9 3*4=12 3*5=15 3*6=18 3*7=21 3*8=24 3*9=27 3*10=30
4*1=4 4*2=8 4*3=12 4*4=16 4*5=20 4*6=24 4*7=28 4*8=32 4*9=36 4*10=40
5*1=5 5*2=10 5*3=15 5*4=20 5*5=25 5*6=30 5*7=35 5*8=40 5*9=45 5*10=50