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BigInt.h
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C/C++ Source or Header
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1990-05-15
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// BigInt.h -- Multiple-precision integer class
// $Header: /afs/alw.nih.gov/unix/sun4_40c/usr/local/src/nihcl-3.0/share/ex/RCS/BigInt.h,v 3.0 90/05/15 22:43:27 kgorlen Rel $
#include <stdio.h>
#include <iostream.h>
class BigInt {
char* digits; // pointer to digit array in free store
unsigned ndigits; // number of digits
BigInt(char* d, unsigned n) { // constructor function
digits = d;
ndigits = n;
}
friend DigitStream;
char* scanChunk(istream&); // read a chunk of digits
public:
BigInt(const char*); // constructor function
BigInt(unsigned n =0); // constructor function
BigInt(const BigInt&); // copy constructor function
void operator=(const BigInt&); // assignment
BigInt operator+(const BigInt&) const; // addition operator
// function
void print(FILE* f =stdout) const; // printing function
~BigInt() { delete digits; } // destructor function
void printOn(ostream&) const; // printing function
void scanFrom(istream&); // reading function
};
inline istream& operator>>(istream& strm, BigInt& b)
{
b.scanFrom(strm);
return strm;
}
inline ostream& operator<<(ostream& strm, const BigInt& b)
{
b.printOn(strm);
return strm;
}
class DigitStream {
char* dp; // pointer to current digit
unsigned nd; // number of digits remaining
public:
DigitStream(const BigInt& n) { // constructor function
dp = n.digits;
nd = n.ndigits;
}
unsigned operator++() { // return current digit
// and advance
if (nd == 0) return 0;
else {
nd--;
return *dp++;
}
}
};