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Some tweaks and fixes for Common::Rational

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* Fix Common::gcd to work with negative input
* This fixes a bug in Common::Rational's multiplication code
* Add some more basic unit tests (including one which checks for
  the now fixed multiplication bug)
* cleanup

svn-id: r49064
This commit is contained in:
Max Horn 2010-05-17 22:07:58 +00:00
parent c7fa1074fb
commit 00cd966f3d
3 changed files with 59 additions and 25 deletions
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2
common/algorithm.h
View File

@ -227,6 +227,8 @@ void sort(T first, T last) {
*/
template<class T>
T gcd(T a, T b) {
if (a <= 0) a = -a;
if (b <= 0) b = -b;
while (a > 0) {
T tmp = a;
a = b % a;

26
common/rational.cpp
View File

@ -49,7 +49,7 @@ Rational::Rational(int num, int denom) {
void Rational::cancel() {
// Cancel the fraction by dividing both the num and the denom
// by their greatest common denom.
// by their greatest common divisor.
int gcd = Common::gcd(_num, _denom);
@ -144,65 +144,49 @@ const Rational Rational::operator-() const {
const Rational Rational::operator+(const Rational &right) const {
Rational tmp = *this;
tmp += right;
return tmp;
}
const Rational Rational::operator-(const Rational &right) const {
Rational tmp = *this;
tmp -= right;
return tmp;
}
const Rational Rational::operator*(const Rational &right) const {
Rational tmp = *this;
tmp *= right;
return tmp;
}
const Rational Rational::operator/(const Rational &right) const {
Rational tmp = *this;
tmp /= right;
return tmp;
}
const Rational Rational::operator+(int right) const {
Rational tmp = *this;
tmp += right;
return tmp;
}
const Rational Rational::operator-(int right) const {
Rational tmp = *this;
tmp -= right;
return tmp;
}
const Rational Rational::operator*(int right) const {
Rational tmp = *this;
tmp *= right;
return tmp;
}
const Rational Rational::operator/(int right) const {
Rational tmp = *this;
tmp /= right;
return tmp;
}
@ -296,33 +280,25 @@ Rational::operator double() const {
const Rational operator+(int left, const Rational &right) {
Rational tmp = right;
tmp += left;
return tmp;
}
const Rational operator-(int left, const Rational &right) {
Rational tmp = right;
tmp -= left;
return tmp;
}
const Rational operator*(int left, const Rational &right) {
Rational tmp = right;
tmp *= left;
return tmp;
}
const Rational operator/(int left, const Rational &right) {
Rational tmp = right;
tmp /= left;
return tmp;
}

56
test/common/rational.h
View File

@ -35,4 +35,60 @@ public:
TS_ASSERT(!(7 > r4));
TS_ASSERT(!(7 >= r4));
}
void test_assign() {
Common::Rational r0(6, 3);
Common::Rational r1(1, 2);
TS_ASSERT(r0 == 2);
TS_ASSERT(r1 == Common::Rational(1, 2));
r0 = r1;
TS_ASSERT(r0 == r1);
TS_ASSERT(r0 == Common::Rational(1, 2));
}
void test_negative() {
Common::Rational r0(6, 3);
Common::Rational r1(1, 2);
r0 = -r0;
r1 = -r1;
TS_ASSERT(r0 == -2);
TS_ASSERT(r1 == Common::Rational(-1, 2));
TS_ASSERT(r1 == Common::Rational(1, -2));
}
void test_add_sub() {
const Common::Rational r0(6, 3);
const Common::Rational r1(1, 2);
TS_ASSERT(r0 + r1 == Common::Rational(5, 2));
TS_ASSERT(r1 + r0 == Common::Rational(5, 2));
TS_ASSERT(r0 - r1 == Common::Rational(3, 2));
TS_ASSERT(r1 - r0 == Common::Rational(-3, 2));
}
void test_mul() {
const Common::Rational r0(6, 3);
const Common::Rational r1(1, 2);
const Common::Rational r2(15, 14);
const Common::Rational r3(7,3);
const Common::Rational r4(5,2);
TS_ASSERT_EQUALS(r0 * r1, 1);
TS_ASSERT_EQUALS(r2 * r3, r4);
TS_ASSERT_EQUALS((-r2) * r3, -r4);
TS_ASSERT_EQUALS(r2 * (-r3), -r4);
TS_ASSERT_EQUALS((-r2) * (-r3), r4);
}
void test_div() {
Common::Rational r0(6, 3);
Common::Rational r1(1, 2);
TS_ASSERT(r0 / r1 == 4);
}
};