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Linux密码恢复

王骏的BLOG — Thu, 07 Aug 2008 10:22:00 GMT

1）用第一张安装盘引导
2）进入提示符后输入linux rescue进入拯救模式
3）提示挂接/mnt/sysimage成功后
chroot /mnt/sysimage
echo "0">/selinux/enforce
passwd root xxxxxx

如果没有输入echo "0">/selinux/enforce,会产生如下错误：
passwd: user_u:system_r:unconfined_t is not authorized to change the password root

如果没有启动盘，可以在到到grub界面是按'a',然后为kernel命令行添加selinux=0参数，然后回车继续启动。

VC2005调试器的一个小小bug

周星星 — Thu, 07 Aug 2008 02:00:00 GMT

HOOKING A COM INTERFACE

布伦特原油 — Wed, 06 Aug 2008 15:47:00 GMT

如题，可能需要将ATL COM 接口的调用方法HOOK出来，经过试验有两种方法可行。

1. HOOK API CoCreateInstance.
2. HOOK Message。

在此Mark一下方法2,以后如果有时间有人需要，我将做一个COM DLL TOOL.

     以下说明怎么HOOK 1个函数的COM DLL. 此接口继承 IDispatch.
     HOOKING到指定的进程，采用DLL共享方式，
    对感兴趣的EXE建立指定接口的Instance.
    智能指针创建实例后，修改虚函数表，可以单独HOOK Invoke函数，这样最简单也最通用。

struct _HookNavigatorVtbl
{
    HRESULT ( STDMETHODCALLTYPE *QueryInterface)(IUnknown * This, REFIID riid, void **ppvObject);
    ULONG    ( STDMETHODCALLTYPE *AddRef)(IUnknown * This);
    ULONG    ( STDMETHODCALLTYPE *Release)(IUnknown * This);
    HRESULT ( STDMETHODCALLTYPE *GetTypeInfoCount )(IUnknown * This,UINT *pctinfo);
    HRESULT ( STDMETHODCALLTYPE *GetTypeInfo )( IUnknown * This,UINT iTInfo,LCID lcid,ITypeInfo **ppTInfo);
    HRESULT ( STDMETHODCALLTYPE *GetIDsOfNames )( IUnknown * This,REFIID riid,LPOLESTR *rgszNames,UINT cNames,LCID lcid,DISPID *rgDispId);
    HRESULT ( STDMETHODCALLTYPE *Invoke )( IUnknown * This,DISPID dispIdMember,REFIID riid,LCID lcid,WORD wFlags,DISPPARAMS *pDispParams,
        VARIANT *pVarResult,EXCEPINFO *pExcepInfo,UINT *puArgErr);

    HRESULT (STDMETHODCALLTYPE *Initialize)(BSTR FilePathName );
};

然后建立一个对象

struct _IHookNavigatorSystem
{
struct _HookNavigatorVtbl *lpVtbl;
}* iHook = NULL;

实现

HRESULT (STDMETHODCALLTYPE *OldInitialize)(BSTR FilePathName) = NULL;
HRESULT __stdcall MyInitialize(BSTR FilePathName)
{
MessageBeep(1000);
OutputDebugString("$$$$$$ Incomming MyInitialize");
return OldInitialize(FilePathName);
}

修改函数地址

IXNavigatorPtr Navigator;
BOOL OnHookNavigator()
{
    DWORD dwOldProtect;
    HRESULT hr = Navigator.CreateInstance( __uuidof(XNavigator));
    if ( !SUCCEEDED(hr))
    {
        MessageBox( "Error CreateInstance(XNavigator)",NULL,MB_OK|MB_ICONSTOP);
        return FALSE;
    }

    iHook = (_IHookNavigatorSystem*)Navigator.GetInterfacePtr();
    if(!iHook)
    return FALSE;

    //TCHAR szMessage[128];
    //_stprintf(szMessage,"$$$$$$ iHook = %x ", iHook);            OutputDebugString(szMessage); // To DebugView
    //_stprintf(szMessage,"$$$$$$ lpVtbl = %x ", iHook->lpVtbl);    OutputDebugString(szMessage); // To DebugView

    OldInitialize    = iHook->lpVtbl->Initialize;

    if (VirtualProtect(iHook->lpVtbl, sizeof(_IHookNavigatorSystem), PAGE_READWRITE, &dwOldProtect))
    {
        iHook->lpVtbl->Initialize = MyInitialize;
        OutputDebugString("Hook (XNavigator) Success");
        return TRUE;
    }
    return FALSE;
}

取消HOOK

void OnStopHookNavigator()
{
    if (iHook &&
        iHook->lpVtbl->Initialize == MyInitialize){
             iHook->lpVtbl->Initialize = OldInitialize;
          iHook = NULL;
         OutputDebugString("Hook Restore Success");
    }

    if (Navigator)
    {
        Navigator.Release();
        Navigator = NULL;
    }
}

根据extid 获得nandflash 的一些属性

liu090 — Wed, 06 Aug 2008 05:34:00 GMT

2.6.14 内核MTD 中关于获得nand flash 的一些属性的方法:

设置READID 命令后开始读ID
1.读ID 第1byte
maker_id = =read_byte;
2.读ID 第2byte
device_id =read_byte;
3.读ID 第3byte
cellinfo = read_byte;
4.读ID 第4byte
extid = read_byte;

根据该扩展id可计算
    1.page 大小:
page_size = 1024 << (extid & 0x3);
    2. spare 大小:
extid >>= 2;
spare_size = (8 << (extid & 0x01)) * (page_size >> 9);
    3. block 大小:
extid >>= 2;
block_size = (64 * 1024) << (extid & 0x03);
    4.bus width:
extid >>= 2;
bus width = (extid & 0x01) ? 16bit: 8bit;

如何重载operator new,delete操作

Diviner — Wed, 06 Aug 2008 05:31:00 GMT

得承认，这不困难，下面的这种做法可能看起来舒服些。

#include

namespace HL
{
class mallocHeap
{
public:

~mallocHeap (void) {}

inline void * malloc (size_t sz)
{
return ::malloc (sz);
}

inline void free (void * ptr)
{
::free (ptr);
}

inline size_t getSize (void * ptr)
{
return ::_msize (ptr);
}
};

template
class PerClassHeap
{
public:
inline void * operator new (size_t sz)
{
printf("Malloc one\n");
return getHeap()->malloc (sz);
}
inline void operator delete (void * ptr)
{
printf("delete one\n");
getHeap()->free (ptr);
}
inline void * operator new[] (size_t sz)
{
return getHeap()->malloc (sz);
}
inline void operator delete[] (void * ptr)
{
getHeap()->free (ptr);
}
// For some reason, g++ needs placement new to be overridden
// as well, at least in conjunction with use of the STL.
// Otherwise, this should be superfluous.
inline void * operator new (size_t sz, void * p) { return p; }
inline void * operator new[] (size_t sz, void * p) { return p; }

private:
inline static SuperHeap * getHeap (void)
{
static SuperHeap theHeap;
return &theHeap;
}
};

}

class TestB : public HL::PerClassHeap
{

};

101道算法题--转的

lostpencil — Fri, 01 Aug 2008 07:59:00 GMT

1. Given a rectangular (cuboidal for the puritans) cake with a rectangular piece removed (any size or orientation), how would you cut the remainder of the cake into two equal halves with one straight cut of a knife ?
2. You're given an array containing both positive and negative integers and required to find the sub-array with the largest sum (O(N) a la KBL). Write a routine in C for the above.
3. Given an array of size N in which every number is between 1 and N, determine if there are any duplicates in it. You are allowed to destroy the array if you like. [ I ended up giving about 4 or 5 different solutions for this, each supposedly better than the others ].
4. Write a routine to draw a circle (x ** 2 + y ** 2 = r ** 2) without making use of any floating point computations at all. [ This one had me stuck for quite some time and I first gave a solution that did have floating point computations
5. Given only putchar (no sprintf, itoa, etc.) write a routine putlong that prints out an unsigned long in decimal. [ I gave the obvious solution of taking % 10 and / 10, which gives us the decimal value in reverse order. This requires an array since we need to print it out in the correct order. The interviewer wasn't too pleased and asked me to give a solution which didn't need the array
6. Give a one-line C expression to test whether a number is a power of 2. [No loops allowed - it's a simple test.
7. Given an array of characters which form a sentence of words, give an efficient algorithm to reverse the order of the words (not characters) in it.
8. How many points are there on the globe where by walking one mile south, one mile east and one mile north you reach the place where you started.
9. Give a very good method to count the number of ones in a "n" (e.g. 32) bit number.
ANS. Given below are simple solutions, find a solution that does it in log (n) steps.
Iterativefunction iterativecount (unsigned int n)beginint count=0;while (n)begincount += n & 0x1 ;n >>= 1;endreturn count;endSparse Countfunction sparsecount (unsigned int n)beginint count=0;while (n)begincount++;n &= (n-1);endreturn count ;end
10. What are the different ways to implement a condition where the value of x can be either a 0 or a 1. Apparently the if then else solution has a jump when
written out in assembly. if (x == 0) y=a else y=b There is a logical, arithmetic and a data structure solution to the above problem.
11. Reverse a linked list.
12. Insert in a sorted list
13. In a X's and 0's game (i.e. TIC TAC TOE) if you write a program for this give a fast way to generate the moves by the computer. I mean this should be the fastest way possible.
The answer is that you need to store all possible configurations of the board and the move that is associated with that. Then it boils down to just accessing the right element and getting the corresponding move for it. Do some analysis and do some more optimization in storage since otherwise it becomes infeasible to get the required storage in a DOS machine.
14. I was given two lines of assembly code which found the absolute value of a number stored in two's complement form. I had to recognize what the code was doing. Pretty simple if you know some assembly and some fundaes on number representation.
15. Give a fast way to multiply a number by 7.
16. How would go about finding out where to find a book in a library. (You don't know how exactly the books are organized beforehand).
17. Linked list manipulation.
18. Tradeoff between time spent in testing a product and getting into the market first.
19. What to test for given that there isn't enough time to test everything you want to.
20. First some definitions for this problem: a) An ASCII character is one byte long and the most significant bit in the byte is always '0'. b) A Kanji character is two bytes long. The only characteristic of a Kanji character is that in its first byte the most significant bit is '1'.
Now you are given an array of a characters (both ASCII and Kanji) and, an index into the array. The index points to the start of some character. Now you need to write a function to do a backspace (i.e. delete the character before the given index).
21. Delete an element from a doubly linked list.
22. Write a function to find the depth of a binary tree.
23. Given two strings S1 and S2. Delete from S2 all those characters which occur in S1 also and finally create a clean S2 with the relevant characters deleted.
24. Assuming that locks are the only reason due to which deadlocks can occur in a system. What would be a foolproof method of avoiding deadlocks in the system.
25. Reverse a linked list.
Ans: Possible answers -
iterative loop
curr->next = prev;
prev = curr;
curr = next;
next = curr->next
endloop
recursive reverse(ptr)
if (ptr->next == NULL)
return ptr;
temp = reverse(ptr->next);
temp->next = ptr;
return ptr;
end
26. Write a small lexical analyzer - interviewer gave tokens. expressions like "a*b" etc.
27. Besides communication cost, what is the other source of inefficiency in RPC? (answer : context switches, excessive buffer copying). How can you optimize the communication? (ans : communicate through shared memory on same machine, bypassing the kernel _ A Univ. of Wash. thesis)
28. Write a routine that prints out a 2-D array in spiral order!
29. How is the readers-writers problem solved? - using semaphores/ada .. etc.
30. Ways of optimizing symbol table storage in compilers.
31. A walk-through through the symbol table functions, lookup() implementation etc. - The interviewer was on the Microsoft C team.
32. A version of the "There are three persons X Y Z, one of which always lies".. etc..
33. There are 3 ants at 3 corners of a triangle, they randomly start moving towards another corner.. what is the probability that they don't collide.
34. Write an efficient algorithm and C code to shuffle a pack of cards.. this one was a feedback process until we came up with one with no extra storage.
35. The if (x == 0) y = 0 etc..
36. Some more bitwise optimization at assembly level
37. Some general questions on Lex, Yacc etc.
38. Given an array t[100] which contains numbers between 1..99. Return the duplicated value. Try both O(n) and O(n-square).
39. Given an array of characters. How would you reverse it. ? How would you reverse it without using indexing in the array.
40. Given a sequence of characters. How will you convert the lower case characters to upper case characters. ( Try using bit vector - solutions given in the C lib -typec.h)
41. Fundamentals of RPC.
42. Given a linked list which is sorted. How will u insert in sorted way.
43. Given a linked list How will you reverse it.
44. Give a good data structure for having n queues ( n not fixed) in a finite memory segment. You can have some data-structure separate for each queue. Try to use at least 90% of the memory space.
45. Do a breadth first traversal of a tree.
46. Write code for reversing a linked list.
47. Write, efficient code for extracting unique elements from a sorted list of array. e.g. (1, 1, 3, 3, 3, 5, 5, 5, 9, 9, 9, 9) -> (1, 3, 5, 9).
48. Given an array of integers, find the contiguous sub-array with the largest sum.
ANS. Can be done in O(n) time and O(1) extra space. Scan array from 1 to n. Remember the best sub-array seen so far and the best sub-array ending in i.
49. Given an array of length N containing integers between 1 and N, determine if it contains any duplicates.
ANS.
50. Sort an array of size n containing integers between 1 and K, given a temporary scratch integer array of size K.
ANS. Compute cumulative counts of integers in the auxiliary array. Now scan the original array, rotating cycles! [Can someone word this more nicely?
51. An array of size k contains integers between 1 and n. You are given an additional scratch array of size n. Compress the original array by removing duplicates in it. What if k << n?
ANS. Can be done in O(k) time i.e. without initializing the auxiliary array!
52. An array of integers. The sum of the array is known not to overflow an integer. Compute the sum. What if we know that integers are in 2's complement form?
ANS. If numbers are in 2's complement, an ordinary looking loop like for(i=total=0;i< n;total+=array[i++]); will do. No need to check for overflows!
53. An array of characters. Reverse the order of words in it.
ANS. Write a routine to reverse a character array. Now call it for the given array and for each word in it.
* 54. An array of integers of size n. Generate a random permutation of the array, given a function rand_n() that returns an integer between 1 and n, both inclusive, with equal probability. What is the expected time of your algorithm?
ANS. "Expected time" should ring a bell. To compute a random permutation, use the standard algorithm of scanning array from n downto 1, swapping i-th element with a uniformly random element <= i-th. To compute a uniformly random integer between 1 and k (k < n), call rand_n() repeatedly until it returns a value in the desired range.
55. An array of pointers to (very long) strings. Find pointers to the (lexicographically) smallest and largest strings.
ANS. Scan array in pairs. Remember largest-so-far and smallest-so-far.
Compare the larger of the two strings in the current pair with largest-so-far to update it. And the smaller of the current pair with the smallest-so-far to update it. For a total of <= 3n/2 strcmp() calls. That's also the lower bound.
56. Write a program to remove duplicates from a sorted array.
ANS. int remove_duplicates(int * p, int size)
{
int current, insert = 1;
for (current=1; current < size; current++)
if (p[current] != p[insert-1])
{
p[insert] = p[current];
current++;
insert++;
} else
current++;
return insert;
}
57. C++ ( what is virtual function ? what happens if an error occurs in constructor or destructor. Discussion on error handling, templates, unique features of C++. What is different in C++, ( compare with unix).
58. Given a list of numbers ( fixed list) Now given any other list, how can you efficiently find out if there is any element in the second list that is an element of the first list (fixed list).
59. Given 3 lines of assembly code : find it is doing. IT was to find absolute value.
60. If you are on a boat and you throw out a suitcase, Will the level of water increase.
61. Print an integer using only putchar. Try doing it without using extra storage.
62. Write C code for (a) deleting an element from a linked list (b) traversing a linked list
63. What are various problems unique to distributed databases
64. Declare a void pointer ANS. void *ptr;
65. Make the pointer aligned to a 4 byte boundary in a efficient manner ANS. Assign the pointer to a long number and the number with 11...1100 add 4 to the number
66. What is a far pointer (in DOS)
67. What is a balanced tree
68. Given a linked list with the following property node2 is left child of node1, if node2 < node1 else, it is the right child.
O P
|
|
O A
|
|
O B
|
|
O C
How do you convert the above linked list to the form without disturbing the property. Write C code for that.
O P
|
|
O B
/ \
/ \
/ \
O ? O ?
determine where do A and C go
69. Describe the file system layout in the UNIX OS
ANS. describe boot block, super block, inodes and data layout
70. In UNIX, are the files allocated contiguous blocks of data
ANS. no, they might be fragmented
How is the fragmented data kept track of
ANS. Describe the direct blocks and indirect blocks in UNIX file system
71. Write an efficient C code for 'tr' program. 'tr' has two command line arguments. They both are strings of same length. tr reads an input file, replaces each character in the first string with the corresponding character in the second string. eg. 'tr abc xyz' replaces all 'a's by 'x's, 'b's by 'y's and so on. ANS.
a) have an array of length 26.
put 'x' in array element corr to 'a'
put 'y' in array element corr to 'b'
put 'z' in array element corr to 'c'
put 'd' in array element corr to 'd'
put 'e' in array element corr to 'e'
and so on.
the code
while (!eof)
{
c = getc();
putc(array[c - 'a']);
}
72. what is disk interleaving
73. why is disk interleaving adopted
74. given a new disk, how do you determine which interleaving is the best a) give 1000 read operations with each kind of interleaving determine the best interleaving from the statistics
75. draw the graph with performance on one axis and 'n' on another, where 'n' in the 'n' in n-way disk interleaving. (a tricky question, should be answered carefully)
76. I was a c++ code and was asked to find out the bug in that. The bug was that he declared an object locally in a function and tried to return the pointer to that object. Since the object is local to the function, it no more exists after returning from the function. The pointer, therefore, is invalid outside.
77. A real life problem - A square picture is cut into 16 squares and they are
shuffled. Write a program to rearrange the 16 squares to get the original big square.
78.
int *a;
char *c;
*(a) = 20;
*c = *a;
printf("%c",*c);
what is the output?
79. Write a program to find whether a given m/c is big-endian or little-endian!
80. What is a volatile variable?
81. What is the scope of a static function in C ?
82. What is the difference between "malloc" and "calloc"?
83. struct n { int data; struct n* next}node;
node *c,*t;
c->data = 10;
t->next = null;
*c = *t;
what is the effect of the last statement?
84. If you're familiar with the ? operator x ? y : z
you want to implement that in a function: int cond(int x, int y, int z); using only ~, !, ^, &, +, |, <<, >> no if statements, or loops or anything else, just those operators, and the function should correctly return y or z based on the value of x. You may use constants, but only 8 bit constants. You can cast all you want. You're not supposed to use extra variables, but in the end, it won't really matter, using vars just makes things cleaner. You should be able to reduce your solution to a single line in the end though that requires no extra vars.
85. You have an abstract computer, so just forget everything you know about computers, this one only does what I'm about to tell you it does. You can use as many variables as you need, there are no negative numbers, all numbers are integers. You do not know the size of the integers, they could be infinitely large, so you can't count on truncating at any point. There are NO comparisons allowed, no if statements or anything like that. There are only four operations you can do on a variable.
1) You can set a variable to 0.
2) You can set a variable = another variable.
3) You can increment a variable (only by 1), and it's a post increment.
4) You can loop. So, if you were to say loop(v1) and v1 = 10, your loop would execute 10 times, but the value in v1 wouldn't change so the first line in the loop can change value of v1 without changing the number of times you loop.
You need to do 3 things.
1) Write a function that decrements by 1.
2) Write a function that subtracts one variable from another.
3) Write a function that divides one variable by another.
4) See if you can implement all 3 using at most 4 variables. Meaning, you're not making function calls now, you're making macros. And at most you can have 4 variables. The restriction really only applies to divide, the other 2 are easy to do with 4 vars or less. Division on the other hand is dependent on the other 2 functions, so, if subtract requires 3 variables, then divide only has 1 variable left unchanged after a call to subtract. Basically, just make your function calls to decrement and subtract so you pass your vars in by reference, and you can't declare any new variables in a function, what you pass in is all it gets.
* 86. Under what circumstances can one delete an element from a singly linked list in constant time?
ANS. If the list is circular and there are no references to the nodes in the list from anywhere else! Just copy the contents of the next node and delete the next node. If the list is not circular, we can delete any but the last node using this idea. In that case, mark the last node as dummy!
* 87. Given a singly linked list, determine whether it contains a loop or not.
ANS. (a) Start reversing the list. If you reach the head, gotcha! there is a loop!
But this changes the list. So, reverse the list again.
(b) Maintain two pointers, initially pointing to the head. Advance one of them one node at a time. And the other one, two nodes at a time. If the latter overtakes the former at any time, there is a loop!
p1 = p2 = head;
do {
p1 = p1->next;
p2 = p2->next->next;
} while (p1 != p2);
88. Given a singly linked list, print out its contents in reverse order. Can you do it without using any extra space?
ANS. Start reversing the list. Do this again, printing the contents.
89. Given a binary tree with nodes, print out the values in pre-order/in-order/post-order without using any extra space.
90. Reverse a singly linked list recursively. The function prototype is node * reverse (node *) ;
ANS.
node * reverse (node * n)
{
node * m ;
if (! (n && n -> next))
return n ;
m = reverse (n -> next) ;
n -> next -> next = n ;
n -> next = NULL ;
return m ;
}
91. Given a singly linked list, find the middle of the list.
HINT. Use the single and double pointer jumping. Maintain two pointers, initially pointing to the head. Advance one of them one node at a time. And the other one, two nodes at a time. When the double reaches the end, the single is in the middle. This is not asymptotically faster but seems to take less steps than going through the list twice.
92. Reverse the bits of an unsigned integer.
ANS.
#define reverse(x) \
(x=x>>16|(0x0000ffff&x)<<16, \
x=(0xff00ff00&x)>>8|(0x00ff00ff&x)<<8, \
x=(0xf0f0f0f0&x)>>4|(0x0f0f0f0f&x)<<4, \
x=(0xcccccccc&x)>>2|(0x33333333&x)<<2, \
x=(0xaaaaaaaa&x)>>1|(0x55555555&x)<<1)
* 93. Compute the number of ones in an unsigned integer.
ANS.
#define count_ones(x) \
(x=(0xaaaaaaaa&x)>>1+(0x55555555&x), \
x=(0xcccccccc&x)>>2+(0x33333333&x), \
x=(0xf0f0f0f0&x)>>4+(0x0f0f0f0f&x), \
x=(0xff00ff00&x)>>8+(0x00ff00ff&x), \
x=x>>16+(0x0000ffff&x))
94. Compute the discrete log of an unsigned integer.
ANS.
#define discrete_log(h) \
(h=(h>>1)|(h>>2), \
h|=(h>>2), \
h|=(h>>4), \
h|=(h>>8), \
h|=(h>>16), \
h=(0xaaaaaaaa&h)>>1+(0x55555555&h), \
h=(0xcccccccc&h)>>2+(0x33333333&h), \
h=(0xf0f0f0f0&h)>>4+(0x0f0f0f0f&h), \
h=(0xff00ff00&h)>>8+(0x00ff00ff&h), \
h=(h>>16)+(0x0000ffff&h))
If I understand it right, log2(2) =1, log2(3)=1, log2(4)=2..... But this macro does not work out log2(0) which does not exist! How do you think it should be handled?
* 95. How do we test most simply if an unsigned integer is a power of two?
ANS. #define power_of_two(x) \ ((x)&&(~(x&(x-1))))
96. Set the highest significant bit of an unsigned integer to zero.
ANS. (from Denis Zabavchik) Set the highest significant bit of an unsigned integer to zero
#define zero_most_significant(h) \
(h&=(h>>1)|(h>>2), \
h|=(h>>2), \
h|=(h>>4), \
h|=(h>>8), \
h|=(h>>16))
97. Let f(k) = y where k is the y-th number in the increasing sequence of non-negative integers with the same number of ones in its binary representation as y, e.g. f(0) = 1, f(1) = 1, f(2) = 2, f(3) = 1, f(4) = 3, f(5) = 2, f(6)
= 3 and so on. Given k >= 0, compute f(k).
98. A character set has 1 and 2 byte characters. One byte characters have 0 as the first bit. You just keep accumulating the characters in a buffer. Suppose at some point the user types a backspace, how can you remove the character efficiently. (Note: You cant store the last character typed because the user can type in arbitrarily many backspaces)
99. What is the simples way to check if the sum of two unsigned integers has resulted in an overflow.
100. How do you represent an n-ary tree? Write a program to print the nodes of such a tree in breadth first order.
101. Write the 'tr' program of UNIX. Invoked as
tr -str1 -str2. It reads stdin and prints it out to stdout, replacing every occurance of str1[i] with str2[i].
e.g. tr -abc -xyz
to be and not to be <- input
to ye xnd not to ye <- output

《高质量C++编程指南》摘录

hATEmATH的网上田园 — Tue, 29 Jul 2008 09:32:00 GMT

是摘录，所以只是自己感兴趣的部分，一般是自己不熟悉的地方和觉得讲述的很好的地方。

第六章函数设计

> 如果函数没有参数，则用void 填充.明确的告诉别人，此函数没有参数。

> 有时候函数原本不需要返回值，但为了增加灵活性如支持链式表达，可以附加返回值。
例如字符串拷贝函数strcpy 的原型：
char *strcpy(char *strDest，const char *strSrc);

> 断言用来捕捉程序员认为不应该发生的情况
在编写函数时，先自问：“我打算做哪些假定？”一旦确定了的假定，就要使用断言对假定进行检查。

> int m;
int & n = m;
n 相当于m 的别名（绰号），对n 的任何操作就是对m 的操作。例如有人名叫王小毛，
他的绰号是“三毛”。说“三毛”怎么怎么的，其实就是对王小毛说三道四。

引用和指针的区别：
（1）引用被创建的同时必须被初始化（指针则可以在任何时候被初始化）。
（2）不能有NULL 引用，引用必须与合法的存储单元关联（指针则可以是NULL）。
（3）一旦引用被初始化，就不能改变引用的关系（指针则可以随时改变所指的对象）。

> 实际上“引用”可以做的任何事情“指针”也都能够做，为什么还要“引用”这东西？
答案是“用适当的工具做恰如其分的工作”。
指针能够毫无约束地操作内存中的如何东西，尽管指针功能强大，但是非常危险。如果只需要借用一下某个对象的“别名”，那么就用“引用”，而不要用“指针”，以免发生意外。比如说，某人需要一份证明，本来在文件上盖上公章的印子就行了，如果把取公章的钥匙交给他，那么他就获得了不该有的权利，从而产生潜在的危险。

第7 章内存管理

> C++/C 语言没有办法知道指针所指的内存容量，除非在申请内存时记住它。

> 当数组作为函数的参数进行传递时，该数组自动退化为同类型的指针

> 如果函数的参数是一个指针，不要指望用该指针去申请动态内存。因为编译器总是要为函数的每个参数制作临时副本，指针亦同。

<边看边补充>

ADAPTER(适配器)----类对象结构模式

gaoqing000 — Tue, 29 Jul 2008 00:55:00 GMT

1.意图
将一个类的接口转换成客户希望的另外一个接口.Adapter模式使得原本由于接口不兼容
而不能一起工作的那些类可以一起工作.
2.别名
　　包装器Wrapper.
3.动机
　　有时，为复用而设计的工具箱类不能够被复用的原因仅仅是因为它的接口与专业应用领域
份代码民需要的接中不匹配

WHOIS 查询

布伦特原油 — Mon, 28 Jul 2008 02:06:00 GMT

代码很简单，不过大多数人用不上，比较专业，这里则怎么没法插图片了？

直接下载(RAW)
http://blog.vckbase.com/Files/brent/whois_v02.zip
下载IP纯真库到（QQWry.Dat）同一目录可显示IP地址的中文信息。

直接下载(FULL)
http://codefs.com/__others/whois_v02.zip

难道这就是黑客扫描

布伦特原油 — Sun, 27 Jul 2008 01:49:00 GMT

每天被扫描不下10次，如果没理解错就是当肉鸡当了好几年了

图抓得慢了，断了一片连接从1000号开始向上扫描

time_t 在 CE 和 PC 上编译不一致

玻璃小屋 — Fri, 25 Jul 2008 05:17:00 GMT

vs2005 以及以上在PC系统上，time_t 都编译成 64位的时间了（__time64_t）。
但是在CE系统上还是被编译成 32位的时间（__time32_t）。

问题就来了。。当用 socket 写程序时
定义这样的结构
struct
{
UINT uiCmd;
time_t uiCmdTime;
}

这时 PC 和 CE用socket 传递数据。问题就出来了。。。

不过 CE上面没有 time_t 类型的相关函数 time、gmtime 等~ 可能M$不推荐在CE上用time_t
自己注意一下。

一个图片检索的测试程序

wetwoo的小窝 — Fri, 25 Jul 2008 03:13:00 GMT

一个图片检索的测试程序
下载地址：http://blog.vckbase.com/Files/wetwoo/IQSysPrj.rar

字符串内部查找函数

周星星 — Thu, 24 Jul 2008 10:45:00 GMT

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