Posts

Showing posts from November, 2006

CTags and VIM

Sample generate tags file command
ctags -f {tag file location} --recurse --langmap=C++:.C.h.c.cpp.hpp --languages=C++ --extra=+q --fields=+i --verbose {source parent folder e.g. /usr/my_source/}
After tag file generated, addset tags={tag file location 1}, {tag file location 2} to .vimrc
in VIM
type
:set tags={tag file location 1}, {tag file location 2} or add it to .vimrc in VIM


For ultraedit, the ctag parameter is
-L %fi -f %fo --language-force=C++ --extra=+q --fields=+i



If using VIM as editor, the supported commands are

:ts - tag, class definition as priority
:tj - tag (can use /pattern or /^pattern. Since it is pattern search, it is not binary search mode which would be slow)
:po or ctrl + 't' - older tag search stack
ctrl ']' on selected text to call tag search directly.
: or to scroll for previous calls

(refer http://www.vim.org/htmldoc/tagsrch.html )

VIM commands which is useful when use in conjunction with ctags
shift + * - start to search this word in the document
shift…

Operator overload

A a;

if(a) <--- this will trigger operator bool() and also operator void const*() const{
{
}


}

boost style
(typedef T * (this_type::*unspecified_bool_type)() const;operator unspecified_bool_type() const // never throws{return px == 0? 0: &this_type::get;})

if (a == "ss") <-- a combinations of few operator overload.

Foo(std::string const& s);
Foo(std::string s);

bool operator==(Foo const& lhs, Foo const& rhs);

For []

int& operator[] (unsigned i) { return data[i]; }


class A
{
public:
enum enA { A1, A2, A3 };
A() { }
~A() { }

operator A::enA() { return A2; }

};

void Fn(A::enA e)
{
std::cout << "Fn(A::enA)\n";

}

when
A a;
Fn(a); // Will call Fn(A::enA) due to overload of operator A::enA()

C++ Heap Corruption example

class A {

A(int i)
{
text = (char *)malloc(sizeof (char *)) ;
}

A()
{
text = (char *)malloc(sizeof (char *)) ;
}

virtual ~A()
{
if(text != 0)
{
free(text);
text = 0;
}
}

};


void main()
{
A a;
a = A(123);
}

Polymorphism or inheritance watch out

class B {
char *str;
B(){str = new char[100];}
~B(){delete [] str;}
};
class D : public B {
D(){}
~D(){}
};

B* pB = new D;delete pB; // resource leak cause the base destructor (class B) wasn't call.

Solution 1: The base class "MUST" declare destructor as virtual.
e.g.

virtual ~B(){delete [] str;}

Solution 2: (a prevention mechanism to C++) By declaring class as final so that can't inherit the class. C++ itself does not have final, concept taken from Java.

E.g. http://www.codeproject.com/cpp/finalclass.asp


or use

class __declspec(novtable) YourClassName

Excel VBA

A macro I used to creat the hyperlinks to another sheet which is in sequence

Sub CreateLinks()
Dim i, j, NoNeeded As Integeri = 19 'copy source start rowj = 2 'copy destination start rowNoNeeded = 500 'number of linksDim cellSelect As StringDim cellTarget As String
For j = 2 To NoNeededcellSelect = "A" & CStr(j)Range(cellSelect).SelectcellTarget = "!A" & CStr(i)
ActiveSheet.Hyperlinks.Add Anchor:=Selection, Address:="", SubAddress:=_ "'UNKNOWN (1)'" & cellTarget, TextToDisplay:="'UNKNOWN (1)'" & cellTargeti = i + 1Next j


End Sub