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241 | #include <iostream>
using namespace std;
class polynomial {
public:
//디폴트 생성자
polynomial();
// 복사 생성자
polynomial(const polynomial ©);
//다항식 생성
polynomial(int len, const double * coeff);
//소멸자
~polynomial();
/* 연산자 오버로딩 +*/
friend const polynomial operator +(const polynomial& p1, const polynomial& p2);
friend const polynomial operator +(const polynomial& p1, double c);
friend const polynomial operator +(double c, const polynomial& p1);
/*연산자 오버로딩 -*/
friend const polynomial operator -(const polynomial& p1, const polynomial& p2);
friend const polynomial operator -(const polynomial& p1, double c);
friend const polynomial operator -(double c, const polynomial& p1);
/*연산자 오버로딩 */
friend const polynomial operator *(const polynomial& p1, const polynomial& p2);
friend const polynomial operator *(const polynomial& p1, double c);
friend const polynomial operator *(double c, const polynomial& p1);
//할당 연산자
polynomial& operator =(const polynomial&);
//-연산자
const polynomial operator -() const;
//출력 연산자
friend ostream& operator <<(ostream& os, const polynomial& p1);
//숫자 대입
friend const double evaluate(const polynomial& p1, double value);
private:
double *coef; //계수 배열
int len; //항의 개수
int degree; //최고차수, 지수는 배열의 인덱스
};
int main() {
double c1[] = { 6,5,-2,7 };
double c2[] = { 7,3,-2 };
polynomial p1(4, c1); //객체생성
polynomial p2(3, c2);
cout << "첫 번째 다항식 : " << p1 << endl;
cout << "두 번째 다항식 : " << p2 << endl << endl;
cout << "첫 번째 다항식 + 8 : " << p1 + 8 << endl;
cout << "첫 번째 다항식 - 6 : " << p1 - 6 << endl;
cout << "2 * 두 번째 다항식 : " << p2 * 2 << endl << endl;
cout << "첫 번째 다항식 + 두 번째 다항식 : " << p1 + p2 << endl;
cout << "첫 번째 다항식 - 두 번째 다항식 : " << p1 - p2 << endl;
cout << "첫 번째 다항식 * 두 번째 다항식 : " << p1 * p2 << endl;
cout <<"X=" <<2 <<"를 대입한 결과 : " << evaluate(p1, 2) << endl;
return 0;
}
polynomial::polynomial()
: len(1) {
coef = new double[len];
coef[0] = 0.0;
}
polynomial::polynomial(const polynomial& copy)
: len(copy.len) {
coef = new double[len]; //동적배열
for (int i = 0; i < len; i++)
coef[i] = copy.coef[i];
}
polynomial::polynomial(int n, const double * coeff)
: len(n) {
degree = len - 1;
coef = new double[len];
for (int i = 0; i < len; i++)
coef[i] = coeff[i];
}
polynomial::~polynomial() {
delete[] coef;
coef = NULL;
}
const polynomial operator +(const polynomial& p1, const polynomial& p2) {
polynomial copy1(p1);
polynomial copy2(p2);
if (copy1.len < copy2.len) {
for (int i = 0; i < copy1.len; i++) {
copy2.coef[i] += copy1.coef[i];
}
return copy2;
}
else {
for (int i = 0; i < copy2.len; i++) {
copy1.coef[i] += copy2.coef[i];
}
return copy1;
}
}
const polynomial operator +(const polynomial& p1, double c) {
polynomial copy(p1);
copy.coef[0] += c;
return copy;
}
const polynomial operator +(double c, const polynomial& p1) {
polynomial copy(p1);
copy.coef[0] += c;
return copy;
}
const polynomial operator -(const polynomial& p1, const polynomial& p2) {
polynomial copy1(p1);
polynomial copy2(p2);
if (copy1.len < copy2.len) {
for (int i = 0; i < copy1.len; i++) {
copy2.coef[i] = (-1)*copy2.coef[i];
copy2.coef[i] += copy1.coef[i];
}
return copy1;
}
else {
for (int i = 0; i < copy2.len; i++) {
copy1.coef[i] -= copy2.coef[i];
}
return copy1;
}
}
const polynomial operator -(const polynomial& p1, double c) {
polynomial copy(p1);
copy.coef[0] -= c;
return copy;
}
const polynomial operator -(double c, const polynomial& p1) {
polynomial copy(p1);
copy.coef[0] -= c;
return copy;
}
const polynomial operator *(const polynomial& p1, const polynomial& p2) {
polynomial copy1(p1);
polynomial copy2(p2);
polynomial result;
result.len = p1.degree + p2.degree + 1; //다항식 간 곱셈은 최고차수+최고차수가 새로운 최고차수가 된다. 길이는 상수를 포함하므로 +1
result.coef = new double[result.len];
for (int i = 0; i < result.len; i++)
result.coef[i] = 0;
result.degree = copy1.degree*copy2.degree;
for (int i = 0; i < p1.len; i++) {
for (int j = 0; j < p2.len; j++) {
result.coef[i+j] += p1.coef[i] * p2.coef[j];
}
}
return result;
}
const polynomial operator *(const polynomial& p1, double c) {
polynomial copy(p1);
for(int i=0; i<copy.len;i++)
copy.coef[i] *= c;
return copy;
}
const polynomial operator *(double c, const polynomial& p1) {
polynomial copy(p1);
for (int i = 0; i < copy.len; i++)
copy.coef[i] *= c;
return copy;
}
polynomial& polynomial::operator =(const polynomial& result) {
if (len != result.len) {
delete[] coef;
coef = NULL;
}
len = result.len;
for (int i = 0; i < len; i++)
coef[i] = result.coef[i];
return *this;
}
const polynomial polynomial::operator -() const {
polynomial minus(*this);
for (int i = 0; i <= minus.len; i++)
minus.coef[i] += -1;
return minus;
}
ostream& operator <<(ostream& os, const polynomial& p) {
for (int i = p.len-1; i > 1; i--) {
os << p.coef[i] << "x^" << i<<" ";
if (p.coef[i-1] > 0)
os << '+';
}
os << p.coef[1]<<"x ";
if (p.coef[0] > 0)
os << '+';
if (p.coef[0] != 0)
os << p.coef[0];
return os;
}
const double evaluate(const polynomial& p1, double value) {
double Result=0.0;
polynomial result(p1);
for (int i = 0; i < result.len; i++)
Result += result.coef[i] * pow(value, i); //지수만큼 제곱 후 계수와 곱한다.
return Result;
}
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