C / C++ / MFC

CComVariant result = buf;

CComVariant result;
result = buf; 

		CComVariant result = buf;

executes

#ifndef OLE2ANSI
	CComVariant(LPCSTR lpszSrc)
	{
		vt = VT_EMPTY;
		*this = lpszSrc;
	}
#endif

		CComVariant result2(buf);
executes the same
		CComVariant result3;
executes 
	CComVariant()
	{
		vt = VT_EMPTY;
	}

		result3 = buf;
executes 
	#ifndef OLE2ANSI
	CComVariant& operator=(LPCSTR lpszSrc)
	{
		USES_CONVERSION;
		InternalClear();
		vt = VT_BSTR;
		bstrVal = ::SysAllocString(A2COLE(lpszSrc));

		if (bstrVal == NULL && lpszSrc != NULL)
		{
			vt = VT_ERROR;
			scode = E_OUTOFMEMORY;
		}
		return *this;
	}
	#endif

This line of code from the constructor

		*this = lpszSrc;
executes the = operator code shown above. So all come out the same.

CComVariant v ("foo");
CCOmVariant v = "foo";

#include <iostream>
using std::cout;
using std::endl;

class C
{
public:
    C(int x) : m_n(x) { cout << "in constructor" << endl; }

protected:
    C(const C& rhs) : m_n(rhs.m_n) { cout << "in copy constructor" << endl; }
    const C& operator = (int x) 
        { cout << "in operator =" << endl;
          m_n=x; return *this; }
    int m_n;
};

int main()
{
    C c1 (1);
    C c2 = 2;
    return 0;
}

in constructor
in constructor

CComVariant v(CComVariant("foo")); // Uses a temporary object

#include <iostream>
 
class A {
public:
  A() { cout << "1"; }
  A(const char *) { cout << "2"; }
  A& operator=(const char *){ cout << "3"; }
  A& operator=(const A &){ cout << "4"; }

private:           // Does not compile if private!
  A(const A &) { cout << "5"; }
};
 
int main() {
   A a = "allo";
}

<br />
--------------------Configuration: fun - Win32 Debug--------------------<br />
Compiling...<br />
fun.cpp<br />
C:\Documents and Settings\np0383\My Documents\C++\fun.cpp(66) : error C2679: binary '<<' : no operator defined which takes a right-hand operand of type 'class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >' (or the<br />
re is no acceptable conversion)<br />
Error executing cl.exe.<br />
<br />
fun.exe - 1 error(s), 0 warning(s)<br />

cout << strStack.top() << endl;

#include <iostream>

#include <iostream.h>

#include <iostream>
#include <stack>
#include <string>
using namespace std;

int main(int argc, char* argv[])
{
   
   cout << "Fun with stacks begins" << endl;	
   stack<string> strStack;	
   strStack.push("Nick");	
   strStack.push("Megan");	
   while(!strStack.empty())	
   {		
      cout << strStack.top() << endl;		
      strStack.pop();	
   }	
   cout << "Fun with stacks is over." << endl;
}

<br />
--------------------Configuration: test - Win32 Debug--------------------<br />
Compiling...<br />
test.cpp<br />
c:\documents and settings\np0383\my documents\c++\test.cpp(18) : warning C4508: 'main' : function should return a value; 'void' return type assumed<br />
c:\program files\microsoft visual studio\vc98\include\deque(208) : warning C4786: 'std::reverse_iterator<std::deque<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::allocator<std::basic_string<char,std::char_traits<char>,std<br />
::allocator<char> > > >::const_iterator,std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::basic_string<char,std::char_traits<char>,std::allocator<char> > const &,std::basic_string<char,std::char_traits<char>,std::allocator<ch<br />
ar> > const *,int>' : identifier was truncated to '255' characters in the debug information<br />
        c:\program files\microsoft visual studio\vc98\include\deque(207) : while compiling class-template member function '__thiscall std::deque<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::allocator<std::basic_string<ch<br />
ar,std::char_traits<char>,std::allocator<char> > > >::~std::deque<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::allocator<std::basic_string<char,std::char_traits<char>,std::allocator<char> > > >(void)'<br />
c:\program files\microsoft visual studio\vc98\include\deque(208) : warning C4786: 'std::reverse_iterator<std::deque<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::allocator<std::basic_string<char,std::char_traits<char>,std<br />
::allocator<char> > > >::iterator,std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::basic_string<char,std::char_traits<char>,std::allocator<char> > &,std::basic_string<char,std::char_traits<char>,std::allocator<char> > *,int><br />
' : identifier was truncated to '255' characters in the debug information<br />
        c:\program files\microsoft visual studio\vc98\include\deque(207) : while compiling class-template member function '__thiscall std::deque<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::allocator<std::basic_string<ch<br />
ar,std::char_traits<char>,std::allocator<char> > > >::~std::deque<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::allocator<std::basic_string<char,std::char_traits<char>,std::allocator<char> > > >(void)'<br />
warning C4786: 'std::stack<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::deque<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::allocator<std::basic_string<char,std::char_traits<char>,std::allocat<br />
or<char> > > > >::~stack<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::deque<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::allocator<std::basic_string<char,std::char_traits<char>,std::allocator<br />
<char> > > > >' : identifier was truncated to '255' characters in the debug information<br />
c:\program files\microsoft visual studio\vc98\include\stack(22) : warning C4786: 'std::stack<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::deque<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::al<br />
locator<std::basic_string<char,std::char_traits<char>,std::allocator<char> > > > >::stack<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::deque<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::alloc<br />
ator<std::basic_string<char,std::char_traits<char>,std::allocator<char> > > > >' : identifier was truncated to '255' characters in the debug information<br />
c:\program files\microsoft visual studio\vc98\include\stack(27) : warning C4786: 'std::stack<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::deque<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::al<br />
locator<std::basic_string<char,std::char_traits<char>,std::allocator<char> > > > >::empty' : identifier was truncated to '255' characters in the debug information<br />
c:\program files\microsoft visual studio\vc98\include\deque(208) : warning C4786: 'std::deque<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::allocator<std::basic_string<char,std::char_traits<char>,std::allocator<char> > > <br />
>::~deque<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::allocator<std::basic_string<char,std::char_traits<char>,std::allocator<char> > > >' : identifier was truncated to '255' characters in the debug information<br />
c:\program files\microsoft visual studio\vc98\include\deque(191) : warning C4786: 'std::deque<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::allocator<std::basic_string<char,std::char_traits<char>,std::allocator<char> > > <br />
>::deque<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::allocator<std::basic_string<char,std::char_traits<char>,std::allocator<char> > > >' : identifier was truncated to '255' characters in the debug information<br />
Linking...<br />
<br />
test.exe - 0 error(s), 8 warning(s)<br />

#include <iostream>
#include <vector>
#include <stack>
#include <tchar.h>

using namespace std;


template <class T>
class Math{
	public:
		Math(){};
		T Add(T a, T b) 
		{ 
			return a + b;
		}
		T Subtract(T a, T b)
		{
			return a - b;
		}
		T Multiply(T a, T b) 
		{ 
			return a * b;
		}
		T Divide(T a, T b) 
		{ 
			return a / b;
		}
};

void main()
{


Math<double> dMath;
double dReturn = dMath.Add(12.34,36.654);
cout << "12.34 plus 36.654 = " << dReturn << endl << endl;

printf(_T("vector fun begins...\n\n"));

	vector<int> vList;
	for(int i = 1;i <= 20;i++)
	{
		vList.push_back(i);
		cout << "Number " << i << " added to vector." << endl;
	}

	for(i = 20;i > 0;i--)
	{
		vList.pop_back();
		cout << "Number " << i << " being removed from vector." << endl;		
	}
	vList.~vector();



	cout << "Fun with stacks begins" << endl << endl;

	stack<string> strStack;
	strStack.push("Nick");
	strStack.push("Megan");
	while(!strStack.empty())
	{
		cout << strStack.top() << endl;
		strStack.pop();
	}

	cout << "Fun with stacks is over." << endl;
	


}

<br />
--------------------Configuration: fun - Win32 Debug--------------------<br />
Compiling...<br />
fun.cpp<br />
c:\documents and settings\np0383\my documents\c++\fun.cpp(2) : fatal error C1021: invalid preprocessor command 'pramga'<br />
Error executing cl.exe.<br />
<br />
fun.exe - 1 error(s), 0 warning(s)<br />