X-Git-Url: https://mattmccutchen.net/bigint/bigint.git/blobdiff_plain/05780f4b578d6ae054be0b19b8498d32a4f16c60..c17afa550d0a00498301454195699120e2bf58c5:/BigUnsignedInABase.cc

diff --git a/BigUnsignedInABase.cc b/BigUnsignedInABase.cc
index b668c58..999faaf 100644
--- a/BigUnsignedInABase.cc
+++ b/BigUnsignedInABase.cc
@@ -1,10 +1,20 @@
-/*
-* Matt McCutchen's Big Integer Library
-* http://mysite.verizon.net/mccutchen/bigint/
-*/
-
 #include "BigUnsignedInABase.hh"
 
+BigUnsignedInABase::BigUnsignedInABase(const Digit *d, Index l, Base base)
+	: NumberlikeArray<Digit>(d, l), base(base) {
+	// Check the base
+	if (base < 2)
+		throw "BigUnsignedInABase::BigUnsignedInABase(const Digit *, Index, Base): The base must be at least 2";
+
+	// Validate the digits.
+	for (Index i = 0; i < l; i++)
+		if (blk[i] >= base)
+			throw "BigUnsignedInABase::BigUnsignedInABase(const Digit *, Index, Base): A digit is too large for the specified base";
+
+	// Eliminate any leading zeros we may have been passed.
+	zapLeadingZeros();
+}
+
 namespace {
 	unsigned int bitLen(unsigned int x) {
 		unsigned int len = 0;
@@ -23,30 +33,29 @@ BigUnsignedInABase::BigUnsignedInABase(const BigUnsigned &x, Base base) {
 	// Check the base
 	if (base < 2)
 		throw "BigUnsignedInABase(BigUnsigned, Base): The base must be at least 2";
-	// Save the base.
-	// This pattern is seldom seen in C++, but the analogous ``this.'' is common in Java.
 	this->base = base;
-	
+
 	// Get an upper bound on how much space we need
-	int maxBitLenOfX = x.getLength() * 8 * sizeof(BigUnsigned::Blk);
+	int maxBitLenOfX = x.getLength() * BigUnsigned::N;
 	int minBitsPerDigit = bitLen(base) - 1;
 	int maxDigitLenOfX = ceilingDiv(maxBitLenOfX, minBitsPerDigit);
-	allocate(maxDigitLenOfX); // Get the space
-	
+	len = maxDigitLenOfX; // Another change to comply with `staying in bounds'.
+	allocate(len); // Get the space
+
 	BigUnsigned x2(x), buBase(base);
 	Index digitNum = 0;
-	
+
 	while (!x2.isZero()) {
 		// Get last digit.  This is like `lastDigit = x2 % buBase, x2 /= buBase'.
 		BigUnsigned lastDigit(x2);
 		lastDigit.divideWithRemainder(buBase, x2);
 		// Save the digit.
-		blk[digitNum] = Digit(lastDigit); // invokes `BigUnsigned ==> unsigned short' converter
+		blk[digitNum] = lastDigit.toUnsignedShort();
 		// Move on.  We can't run out of room: we figured it out above.
 		digitNum++;
 	}
-	
-	// Save the eventual length.
+
+	// Save the actual length.
 	len = digitNum;
 }
 
@@ -68,10 +77,12 @@ BigUnsignedInABase::BigUnsignedInABase(const std::string &s, Base base) {
 	// Save the base.
 	// This pattern is seldom seen in C++, but the analogous ``this.'' is common in Java.
 	this->base = base;
-	
-	len = s.length();
+
+	// `s.length()' is a `size_t', while `len' is a `NumberlikeArray::Index',
+	// also known as an `unsigned int'.  Some compilers warn without this cast.
+	len = Index(s.length());
 	allocate(len);
-	
+
 	Index digitNum, symbolNumInString;
 	for (digitNum = 0; digitNum < len; digitNum++) {
 		symbolNumInString = len - 1 - digitNum;
@@ -84,6 +95,9 @@ BigUnsignedInABase::BigUnsignedInABase(const std::string &s, Base base) {
 			blk[digitNum] = theSymbol - 'a' + 10;
 		else
 			throw "BigUnsignedInABase(std::string, Base): Bad symbol in input.  Only 0-9, A-Z, a-z are accepted.";
+
+		if (blk[digitNum] >= base)
+			throw "BigUnsignedInABase::BigUnsignedInABase(const Digit *, Index, Base): A digit is too large for the specified base";
 	}
 	zapLeadingZeros();
 }
@@ -93,16 +107,19 @@ BigUnsignedInABase::operator std::string() const {
 		throw "BigUnsignedInABase ==> std::string: The default string conversion routines use the symbol set 0-9, A-Z and therefore support only up to base 36.  You tried a conversion with a base over 36; write your own string conversion routine.";
 	if (len == 0)
 		return std::string("0");
-	std::string s;
-	s.reserve(len);
+	// Some compilers don't have push_back, so use a char * buffer instead.
+	char *s = new char[len + 1];
+	s[len] = '\0';
 	Index digitNum, symbolNumInString;
 	for (symbolNumInString = 0; symbolNumInString < len; symbolNumInString++) {
 		digitNum = len - 1 - symbolNumInString;
 		Digit theDigit = blk[digitNum];
 		if (theDigit < 10)
-			s.push_back(char('0' + theDigit));
+			s[symbolNumInString] = char('0' + theDigit);
 		else
-			s.push_back(char('A' + theDigit - 10));
+			s[symbolNumInString] = char('A' + theDigit - 10);
 	}
-	return s;
+	std::string s2(s);
+	delete [] s;
+	return s2;
 }