Reputation: 134
I have to write a program (not using vector, nor using structures nor OOP) which calculates the sum and the product of two polynomials. Here is my code:
//Task 4.19 & 4.20
#include <iostream>
#include <cmath>
double* definePoly(char& symbol, char& coef, int& k)
{
std::cout << "deg(" << symbol << "(x)) = ";
std::cin >> k;
symbol++;
double* a = new double[k];
for (int i = k; i >= 0; i--)
{
std::cout << coef << "_{" << i << "} = ";
std::cin >> a[i];
}
coef++;
return a;
}
void printPoly(int n, double* P, char& symbol)
{
symbol--;
std::cout << symbol << "(x)=";
for (int i = n; i >= 0; i--)
{
if (P[i] != 0)
{
if (P[i] > 0)
{
std::cout << '+';
}
std::cout.setf(std::ios::fixed);
std::cout.precision(2);
std::cout << P[i] << ".x^{" << i << "}";
}
}
std::cout << "\n";
symbol++;
}
double* sumPoly(double* a, int n, double* b, int m, char& symbol)
{ // Task 4.19
symbol++;
double* c = new double[(n + m + abs(n - m)) / 2];
if (n > m)
{
for (int i = 0; i <= m; i++) c[i] = a[i] + b[i];
for (int i = m + 1; i <= n; i++) c[i] = a[i];
}
else if (n < m)
{
for (int i = 0; i <= n; i++) c[i] = a[i] + b[i];
for (int i = n + 1; i <= m; i++) c[i] = b[i];
}
else for (int i = 0; i <= n; i++)c[i] = a[i] + b[i];
return c;
}
double* prodPoly(double* a, int n, double* b, int m, char& symbol)
{ // Task 4.20
symbol++;
double* d = new double[n + m];
for (int p = 0; p <= n + m; p++)
{
d[p] = 0;
for (int i = 0; i <= n; i++)
for (int j = 0; j <= m; j++)
if (i + j == p) d[p] = d[p] + a[i] * b[j];
}
return d;
}
int main()
{
int n, m;
char symbol('P'), coef('a');
double* firstPoly = definePoly(symbol, coef, n);
printPoly(n, firstPoly, symbol);
double* secondPoly = definePoly(symbol, coef, m);
printPoly(m, secondPoly, symbol);
double* sum = sumPoly(firstPoly, n, secondPoly, m, symbol);
std::cout << "Sum:\n";
printPoly((n + m + abs(n - m)) / 2, sum, symbol);
double* prod = prodPoly(firstPoly, n, secondPoly, m, symbol);
std::cout << "Product:\n";
printPoly(n + m, prod, symbol);
/*delete[] firstPoly;
delete[] secondPoly;
delete[] sum;
delete[] prod;*/
return 0;
}
It works perfectly, but when I uncomment the deleting, visual studio tells me that there is an error, otherwise there are leaks.
How can I delete/release the memory in order to solve this problem?
Upvotes: 0
Views: 714
Reputation: 238491
double* a = new double[k]; for (int i = k; std::cin >> a[i];
The index of the last element of an array of k
elements is k - 1
You access the arrays out of bounds in all your loops (this is just one of them) . The behaviour of the program is undefined.
how can i delete dynamic array created in a function
Just like you would delete a dynamic array created outside of a function, and just like you've attempted to delete it:
delete[] firstPoly; // etc
But you must make sure that your program doesn't corrupt its own memory with undefined behaviour.
Upvotes: 7