Bun, dar CString nu are un operator de copiere ?nedo wrote:Daca nu ma insel, aici ar trebui sa fie cam la fel de rapide. O clasa care nu are un membru de copiere va avea atribuit de catre compilator unul, care va face un shalow copy, va copia doar adresele membrilor si le va atribui noilor membri.
Mai pe romaneste:
fool.&m_pstring = foo2.&m_pstring;
si barl.&m_string = bar2.&m_string;
Nu.nedo wrote:O clasa care nu are un membru de copiere va avea atribuit de catre compilator unul, care va face un shalow copy, va copia doar adresele membrilor si le va atribui noilor membri.
Mai pe romaneste:
fool.&m_pstring = foo2.&m_pstring;
si barl.&m_string = bar2.&m_string;
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memcpy(&foo2, &foo1, sizeof(CFoo));
Probabil asa o sa zica nea Adam la inceput. Nu si la sfarsit, daca ceteste mai cu atentie aici: http://www.codexpert.ro/forum/viewtopic ... 121#p13656mesajflaviu wrote:Pai la fel, foo2 cu al sau foo2.m_pstring contine doar adresa stringului str, pe cand bar2 are in bar2.m_string chiar obiectul str cu tot zidu' ....
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CFoo foo2 = foo1; // #1
CBar bar2 = bar1; // #2"Bang, dong, zang!..". Nu va speriati, e un botez la chiezii de la zece.mesajflaviu wrote:[...]
P.S. Parca aud oale si strachini sparte
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class String
{
char* m_pBuffer;
public:
String();
String(const char* p);
String(const String& r);
// ... s.a.m.d.
~String();
};Code: Select all
String::String() : m_pBuffer(0)
{
}
String::String(const char* p)
{
m_pBuffer = new char[strlen(p) + 1];
strcpy(m_pBuffer, p);
}
String::String(const String& r)
{
if(r.m_pBuffer == 0)
{
m_pBuffer = 0;
}
else
{
m_pBuffer = new char[strlen(r.m_pBuffer) + 1];
strcpy(m_pBuffer, r.m_pBuffer);
}
}
String::~String()
{
delete []m_pBuffer;
}
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void DoSomethingCool()
{
String s1 = "Un text lung cat zidu' chinezesc...";
String s2 = s1;
String s3 = s2;
// s.a.m.d.
}
int main()
{
DoSomethingCool();
return 0;
}Code: Select all
class String
{
public:
char* m_pBuffer;
mutable int m_nRefs; // reference count
public:
String();
String(const char* p);
String(const String& r);
// ... s.a.m.d.
~String();
};Code: Select all
String::String() : m_pBuffer(0), m_nRefs(0)
{
}
String::String(const char* p) : m_pBuffer(0), m_nRefs(0)
{
if(p != 0)
{
m_pBuffer = new char[strlen(p) + 1];
strcpy(m_pBuffer, p);
}
}
String::String(const String& r)
{
m_pBuffer = r.m_pBuffer;
m_nRefs = ++r.m_nRefs;
}
String::~String()
{
if(--m_nRefs < 1)
delete []m_pBuffer;
}Code: Select all
void CTestDialog::DumpStringData(const CString& str)
{
const CString* pstr = &str; // pointer to CString object
TRACE1("CString object address: %p\n", pstr);
LPCTSTR pchData = (LPCTSTR)str; // CString::m_pchData member
TRACE1("CString::m_pchData points to: %p\n", pchData);
TRACE1("Memory pointed by CString::m_pchData contains: %s\n", pchData);
CStringData* pStringData = (CStringData*)pchData - 1; // pointer to CStringData structure
long nRefs = pStringData->nRefs; // reference count
TRACE1("Reference count: %d\n\n", nRefs);
}Code: Select all
void CTestDialog::OnButtonTest()
{
TRACE0 ("\n+++++ Construct objects +++++\n\n");
CString* pstr1 = new CString(_T("Un string lung cat zidu' chinezesc..."));
DumpStringData(*pstr1);
CString* pstr2 = new CString(*pstr1);
DumpStringData(*pstr2);
CString* pstr3 = new CString(*pstr2);
DumpStringData(*pstr3);
TRACE0 ("\n----- Destruct objects -----\n\n");
DumpStringData(*pstr1);
delete pstr1;
DumpStringData(*pstr2);
delete pstr2;
DumpStringData(*pstr3);
delete pstr3;
} // <-- put a beakpoint here, start debug then take a look in "Debug" window.