举例：
HugeInt.h:
#ifndef HUGEINT_H
#define HUGEINT_H
#include <iostream>
using std::ostream;
class HugeInt {
friend ostream &operator << ( ostream &, const HugeInt & );
public:
HugeInt( long = 0 );
HugeInt( constchar * );
HugeInt operator + ( const HugeInt & );
HugeInt operator + ( int );
HugeInt operator + ( constchar * );
HugeInt operator * ( int );
HugeInt operator * ( const HugeInt & );
private:
short integer[ 30 ];
};
#endif
HugeInt.cpp:
#include <cctype>
#include <cstring>
#include "hugeint.h"
HugeInt::HugeInt( longvalue )
{
for ( int i = 0; i <= 29; i++ )
integer[ i ] = 0;
for ( int j = 29; value != 0 && j >= 0; j-- ){
integer[ j ] = value % 10;
value /= 10;
}
}
HugeInt::HugeInt( constchar *string )
{
for ( int i = 0; i <= 29; i++ )
integer[ i ] = 0;
int length = strlen( string );
for ( int j = 30 - length, k = 0; j <= 29; j++, k++ )
if ( isdigit( string[ k ] ) )
integer[ j ] = string[ k ] - '0';
}
HugeInt HugeInt::operator + ( const 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;
}
HugeInt HugeInt::operator + ( int op2 )
{
return *this + HugeInt( op2 );
}
HugeInt HugeInt::operator + ( constchar *op2 )
{
return *this + HugeInt( op2 );
}
HugeInt HugeInt::operator * ( const HugeInt &mul )
{
HugeInt temp;
HugeInt tempT;
HugeInt tempN;
int carry = 0;
int n = 0;
for ( int i = 29; i >= 0; i-- ){
for ( int t = 0; t <= 29; t++ ){
tempT.integer[ t ] = 0;
tempN.integer[ t ] = 0;
}
for ( int j = 29; j >= 0; j-- ){
tempT.integer[ j ] = integer[ j ] * mul.integer[ i ] + carry;
if ( tempT.integer[ j ] > 9 ){
carry = tempT.integer[ j ] / 10;
tempT.integer[ j ] %= 10;
}
else
carry = 0;
}
for ( int y = 29; y >= 0; y-- )
tempN.integer[ y - n ] = tempT.integer[ y ];
++n;
temp = temp + tempN;
}
return temp;
}
HugeInt HugeInt::operator * ( int mul )
{
return *this * HugeInt( mul );
}
ostream &operator << ( ostream &output, const HugeInt &num )
{
int i;
for ( i = 0; ( num.integer[ i ] == 0 ) && ( i <= 29 ); i++ )
;
if ( i == 30 )
output << 0;
elsefor ( ; i <= 29; i++ )
output << num.integer[ i ];
return output;
}
main.cpp:
#include <iostream>
using std::cout;
using std::endl;
#include "hugeint1.h"
int main()
{
HugeInt n1( 7654321 );
HugeInt n2( 7891234 );
HugeInt n3( "9999999999999999999999999" );
HugeInt n4( "1" );
HugeInt n5;
HugeInt n6( 1234 );
HugeInt n7( 3478 );
cout << "n1 is " << n1 << "\nn2 is " << n2
<< "\nn3 is " << n3 << "\nn4 is " << n4
<< "\nn5 is " << n5 << "\nn6 is " << n6
<< "\nn7 is " << n7 << "\n\n";
n5 = n1 + n2;
cout << n1 << " + " << n2 << " = " << n5 << "\n\n";
cout << n3 << " + " << n4 << "\n= " << ( n3 + n4 )
<< "\n\n";
n5 = n1 + 9;
cout << n1 << " + " << 9 << " = " << n5 << "\n\n";
n5 = n2 + "10000";
cout << n2 << " + " << "10000" << " = " << n5 << endl;
n5 = n7 * n6;
cout << n7 << " * " << n6 << " = " << n5 << endl;
return 0;
}
输出结果为：
