试图熟悉“3规则”,并且无法让复制构造函数工作。其中一个类私有成员返回0时,它应该有一个值3.动态分配数组的复制构造函数
我不知道为什么当复制构造函数执行时,为该类私有成员提供值为0。有问题的成员是theSize
,它是通过class.cpp中的size()
函数返回的。
class.h
class Catalog {
public:
Catalog (int maxCapacity = 100)
int size() const;
int capacity() const;
void add (Book b);
Catalog(const Catalog& c);
~Catalog();
Catalog& operator= (constCatalog& c) {
if (this != &c) {
delete[] books;
books = new Book[theCapacity];
*books = *(c.books);
}
return *this;
}
private:
Book* books;
int theCapacity;
int theSize;
};
class.cpp
Catalog::Catalog(int maxCapacity) {
theCapacity = maxCapacity;
theSize = 0;
books = new Book[theCapacity];
}
int Catalog::size() const {
return theSize();
}
int Catalog::capacity() const {
return theCapacity;
}
void Catalog::add (Book b)
{
if (theSize < theCapacity || contains(b.getID())) {
if (theSize == 0) {
books[0] = b;
theSize++;
}
else {
if (!contains(b.getID())) {
int i = theSize;
for (; i && b < books[i-1]; --i) {
books[i] = books[i - 1];
}
books[i] = b;
for (; i; --i) {
books[i - 1] = books[i - 1];
}
theSize++;
}
else {
for (int i = 0; i < theSize; ++i) {
if (b == books[i]) {
books[i] = b;
}
}
}
}
// Debugging only
/*for (int i = 0; i < theSize; i++) {
//cout << books[i] << endl;
}*/
}
}
bool Catalog::contains(std::string bookID) const
{
for (int i = 0; i < theSize; ++i)
{
if (books[i].getID() == bookID)
return true;
}
return false;
}
Catalog::Catalog(const Catalog& c) {
books = new Book[c.theSize];
for (int i = 0; i < c.theSize; i++) {
books[i] = c.books[i];
}
Catalog::~Catalog() {
delete[] books;
}
在c1
是return c
在另一个函数的结果,当我打电话c1.size()
的main.cpp后来,通过使用的调试器来自复制构造函数,然后进入析构函数。但c1.size()
返回为0
,虽然复制构造函数theSize = c.size()
的值为3
时,通过。
book.cpp
using namespace std;
/**
* Create a book.
*
* @param id the Gutenberg ID for this book
* @param authorInfo the author of the book
* @param title the title of the book
*/
Book::Book (std::string theId, std::string authorInfo, std::string theTitle)
: id(theId), authorName(authorInfo), title(theTitle)
{
}
bool Book::operator< (const Book& b) const
{
return id < b.id;
}
bool Book::operator== (const Book& b) const
{
return (id == b.id);
}
std::ostream& operator<< (std::ostream& out, const Book& b)
{
cout << b.getID() << "\t"
<< b.getAuthor() << "\t"
<< b.getTitle();
return out;
}
std::istream& operator>> (std::istream& in, Book& b)
{
string line;
getline (in, line);
if (!in.good())
return in;
int tab1 = line.find ("\t");
int tab2 = line.find ("\t", tab1+1);
string id = line.substr(0, tab1);
string author = line.substr (tab1+1, tab2-tab1-1);
string title = line.substr(tab2+1);
b.setID (id);
b.setAuthor (author);
b.setTitle (title);
return in;
}
main.cpp中的零
using namespace std;
Catalog readCatalog(const string& fileName)
{
Catalog c;
ifstream in (fileName);
in >> c;
in.close();
return c;
}
Catalog mergeCatalogs (const Catalog& cat1, const Catalog& cat2)
{
Catalog result (cat1.size() + cat2.size());
int i = 0;
int j = 0;
while (i < cat1.size() && j < cat2.size())
{
Book b1 = cat1.get(i);
Book b2 = cat2.get(j);
if (b1.getID() < b2.getID())
{
result.add(b1);
++i;
}
else
{
result.add(b2);
++j;
}
}
while (i < cat1.size())
{
result.add(cat1.get(i));
++i;
}
while (j < cat2.size())
{
result.add(cat2.get(j));
++j;
}
return result;
}
void mergeCatalogFiles (const string& catalogFile1, const string& catalogFile2)
{
Catalog c1, c2;
c1 = readCatalog(catalogFile1);
cout << catalogFile1 << " contained " << c1.size() << " books." << endl;
c2 = readCatalog(catalogFile2);
cout << catalogFile2 << " contained " << c2.size() << " books." << endl;
Catalog c3 = mergeCatalogs (c1, c2);
cout << "Their merge contains " << c3.size() << " books." << endl;
cout << c3 << flush;
}
int main (int argc, char** argv)
{
if (argc != 3)
{
cerr << "Usage: " << argv[0] <<
"catalogFile1 catalogFile2" << endl;
return -1;
}
string file1 = argv[1];
string file2 = argv[2];
mergeCatalogFiles (file1, file2);
if (Counted::getCurrentCount() == 0)
{
cout << "No memory leak detected." << endl;
return 0;
}
else
{
cout << "Memory leak detected: " << Counted::getCurrentCount() << endl;
return -2;
}
}
'*书籍= *(c.books);'将一个元素,而不是整个数组 – user4581301
复制@ user4581301所以也许'for'循环来复制?还是有更好的方法来复制数组? –
For循环或['std :: copy'](http://en.cppreference.com/w/cpp/algorithm/copy)。 – user4581301