hugeint1.cpp

来自「经典vc教程的例子程序」· C++ 代码 · 共 76 行

// Fig. 8.8: hugeint1.cpp 
// Member and friend function definitions for class HugeInt
#include <string.h>
#include "hugeint1.h"

// Conversion constructor
HugeInt::HugeInt( long val )
{
   int i; 

   for ( i = 0; i <= 29; i++ )
      integer[ i ] = 0;   // initialize array to zero

   for ( i = 29; val != 0 && i >= 0; i-- ) {
      integer[ i ] = val % 10;
      val /= 10;
   }
}

HugeInt::HugeInt( const char *string )
{
   int i, j;

   for ( i = 0; i <= 29; i++ )
      integer[ i ] = 0;

   for ( i = 30 - strlen( string ), j = 0; i <= 29; i++, j++ )
      integer[ i ] = string[ j ] - '0';
}

// Addition
HugeInt HugeInt::operator+( HugeInt &op2 )
{
   HugeInt temp;
   int carry = 0;

   for ( int i = 29; i >= 0; i-- ) {
      temp.integer[ i ] = integer[ i ] + 
                          op2.integer[ i ] + carry;

      if ( temp.integer[ i ] > 9 ) {
         temp.integer[ i ] %= 10;
         carry = 1;
      }
      else
         carry = 0;
   }

   return temp;
}

// Addition
HugeInt HugeInt::operator+( int op2 )
   { return *this + HugeInt( op2 ); }

// Addition
HugeInt HugeInt::operator+( const char *op2 )
   { return *this + HugeInt( op2 ); }

ostream& operator<<( ostream &output, HugeInt &num )
{
   int i;

   for ( i = 0; ( num.integer[ i ] == 0 ) && ( i <= 29 ); i++ )
      ; // skip leading zeros

   if ( i == 30 )
      output << 0;
   else
      for ( ; i <= 29; i++ )
         output << num.integer[ i ];

   return output;
}