C++ Excellant pro

Better algorithm for multiplication

#include 

#include

int fastmult (int x, int y)

 {

  int result;

  result = 0;

  while (y != 0) 

{

    if (y % 2 == 0) 

   {

      x = 2*x;

      y = y/2;

    }

    else 

    {

      result = result + x;

      y = y-1;

    }

  }

  return(result);

}

int main () 

{

  int x, y;

  cout << "Enter two natural numbers: ";

  cin >> x >> y;

  cout << x << " * " << y << " = " << fastmult(x,y) << endl;

  return(0);

}

Count number of characters and lines in a file

#include 

#include

#include 

int main () 

{

  ifstream f1;

  char c;

  int numchars, numlines;

  f1.open("test");

  numchars = 0;

  numlines = 0;

  f1.get(c);

  while (f1) 

   {

    while (f1 && c != '\n') 

    {

      numchars = numchars + 1;

      f1.get(c);

    }

    numlines = numlines + 1;

    f1.get(c);

  }

  cout << "The file has " << numlines << " lines and " 

    << numchars << " characters" << endl;

  return(0);

}

Merge sort

#include

#include

#include 

#include 

int main () 

{

  ifstream f1, f2;

  ofstream f3;

  int i,j;

  f1.open("n1");

  f2.open("n2");

  f3.open("n1n2");

  f1 >> i;

  f2 >> j;

  while (f1 && f2) 

 {

    if (i < j) 

  {

      while (i < j && f1 && f3) 

  {

   f3 << i << endl;

   f1 >> i;

      }

    }

    else 

   {

      while (j <= i && f2 && f3) 

    {

   f3 << j << endl;

   f2 >> j;

      }

    }

  }

  while (f1) 

  {

    f3 << i << endl;

    f1 >> i;

  }

  while (f2) 

 {

    f3 << j << endl;

    f2 >> j;

  }

  return (0);

}