C and C + + code pristine NOTE 1

CH1 better C.

1. Operator overloading specifies that there must be a custom type for the user
2. Some functions that the output does not notice:

   float x = 123.456, y = 12345;

   Cout.precision (2); Show two valid values, others are scientific notation

   cout << x << "" << y << Endl;

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   COUT.SETF (ios::showpoint);//Display the end of the 0

   cout << x << "" << y << Endl;

   ?

   COUT.SETF (Ios::showpos);//Display symbol

   cout << x << "" << y << Endl;

3. Print Address

   Printf ("%p", s);

   cout<< "Address:" <<&s;

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CH2 pointer

1. Distinguish the position of the const

   Const Char *p; Note that *p is constant and cannot be changed.

   char* const P; Note that P is constant and cannot be changed.

Depending on the position of the *.

1. Initialize two-dimensional pointers

   int **a;

   A = new int*[3];//line

   ???? for (int i = 0; i < 4; ++i)

   ???? {

   ???????? A[i] = new int[4];//column

   ????}

   Delete[] A;

   ?

   ?

   ???? int A[][4] = {{1,2,3},{4,5,6},{7,8,9}};

   ???? int (*p) [4] = A;

   ?

   ???? P[i] = = * (p+i);

   ???? P[I][J] = = * (p[i]+j) = = * (* (p+i) +j);

   ?

   ?

   ???? size_t totals = sizeof (a);//entire number of bytes

   ???? size_t totalcols = sizeof (a[0]);//The entire column of bytes

   ???? size_t rows = sizeof (a)/sizeof (a[0]);

   ???? size_t cols = sizeof (a[0])/sizeof (a[0][0]);

   ???? for (int i = 0; i < rows; ++i)

   ???? {

   ???????? for (int j = 0; j < cols; ++j)

   ???????????? cout << P[i][j] << "";

   ???????? cout <<endl;

   ????}

   ???? cout << rows << "<< cols << Endl;

2. function pointers

   Pointers to non-member functions:

   #include <Windows.h>

   #include <iostream>

   ?

   using namespace Std;

   ?

   Int (*FP) (int,int);//Global pointer variable

   void (*farray[]) (void); Can be defined outside the main function or internally. Array of function pointers

   int Max (int a, int b)

   {

   ???? if (a > B)

   ???????? return A;

   ???? Else

   ???? return b;

   }

   int main ()

   {

   ???? fp = Max;

   ???? int a = FP (UP);

   ???? cout << a << Endl;

   return 0;

   }

   ?

   Pointers to member functions:

   #include <Windows.h>

   #include <iostream>

   ?

   using namespace Std;

   ?

   Class C

   {

   Public

   ???? void F () {cout << "c::f \ n";};

   ???? void G () {cout << "c::g \ n";};

   ???? int Max (int a, int b)

   {

   ???? if (a > B)

   ???????? return A;

   ???? Else

   ???? return b;

   }

   };

   ?

   int main ()

   {

   c C;

   void (C::* pmf) () = &C::f; Defines a pointer to a member function

   (C.*PMF) ();//A pointer to a member function that is slightly different from the pointer of a non-member function and has more objects. *

   PMF = &C::g;

   (C.*PMF) ();

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   Int (C::* fp) (int,int) = &C::Max;

   int aa = (C.*FP) (3,4);

   cout << AA << Endl;

   return 0;

   }

Array of pointers to member functions

2. #include <Windows.h>
4. #include <iostream>
6. ?
8. using namespace std;
10. ?
12. class Object
14. {
16. Public:
18. ??? void Retreve () {cout << "object::retreve";}
20. ??? void Insert () {cout << "object::insert";}
22. ??? void Update () {cout << "object::update";}
24. ??? void process (int choice);
26. Private:
28. ??? typedef void(Object::* OMF) (); //From the alias up good
30. ??? Static OMF Farray[3]; //member function pointer array
32. ?
34. };
36. OBJECT::OMF Object::farray[3] = {
38. ?? &object::insert,
40. ?? &object::retreve,
42. ?? &object::update
44. };
46. void Object::p rocess (int choice)
48. {
50. ??? if (Choice >=0 && choice <=2)
52. ??? {
54. ?????? (this->*farray[choice]) ();
56. ?????? cout << Endl;
58. ???}
60. }
62. int Main ()
64. {
66. ??? Object o;
68. ??? for (;;)
70. ??? {
72. ?????? int Choice;
74. ?????? CIN >> Choice;
76. ?????? if (Choice >=0 && choice<=2)
78. ????????? O.process (choice);
80. ?????? Else
82. ?????????? break;
84. ???}
86. ??? return 0;
88. }

1. Encapsulation vs. Incomplete types

   The implementation of a class similar to the source class is to redefine a class similar to the source class and then repack it.

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CH3 Preprocessor

1. Debug mode can run under release under Run, with macro definition implementation

   #define DEBUG 1

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   int main ()

   {

   int i = 2;

   #if DEBUG

   cout << "Debugmod" << Endl;

   #endif

   return 0;

   }

   ?

   The following sentence can also achieve the above function

   ?

#ifdef _DEBUG

cout << "Debugmod" << Endl;

#endif //_DEBUG

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To mix the new C + + code with the old C code, you need to add the following statement

extern "C" void f (); F () is compiled in C environment

1. Character

   Enter \ r newline \ \b Warning \a

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One of the CH4 C standard libraries: for qualified programmers

1. <ctype.h>

Common functions: Is series. Eg:isupper (); Islower (); Isspcace () and so on.

char a = ' a ';

int B = Isalpha (a);

Instance:

2. #include <Windows.h>
4. #include <iostream>
6. #include <ctype.h>
8. #include <stdlib.h>
10. #include <stdio.h>
12. #include <string.h>
14. using namespace std;
16. ?
18. long Atox (char *s)
20. {
22. ??? while (Isspace (*s)) //Kill the opening space, as long as there is a nonzero number that jumps out
24. ?????? s++;
26. ??? long sum;
28. ??? for (sum = 0L; Isxdigit (*s); ++s)
30. ??? {
32. ?????? int Digit;
34. ?????? if (IsDigit (*s))
36. ????????? digit = *s-' 0 ';
38. ?????? Else
40. ????????? digit = ToUpper (*s)-' A ' + 10;
42. ?????? sum = sum*16l + digit;
44. ???}
46. ??? return sum;
48. }
50. ?
52. long Atox (char*s)
54. {
56. ??? char xdigs[] = {0123456789ABCDEF};
58. ??? long sum;
60. ??? while (Isspace (*s))
62. ?????? s++;
64. ??? for (sum = 0; Isxdigit (*s); ++s)
66. ??? {
68. ?????? int digit = STRCHR (Xdigs,toupper (*s))-xdigs; //Find the position of the pointer, that is, the position of the number (0-15 values) to find the position of the first occurrence of the string (*s) in Xdigs.
70. ?????? sum = sum*16l + digit;
72. ???}
74. }
76. long Atox (char *s)
78. {
80. ??? long n = 0;
    1. ??? SSCANF (S, "%lx", &n); Reference code: http://www.91linux.com/html/article/program/cpp/20081130/14121.html
82. ??? return N;
84. }
86. int Main ()
88. {
90. ??? Char* s = "123 abc";
92. ??? //Method one
94. ??? long t = Atox (s);
96. ??? //Method two
98. ??? Char* * ss = NULL;
100. ??? long tt = Strtol (s,ss,16);
102. ??? cout << tt << Endl;
104. ??? return 0;
106. }

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C and C + + code pristine NOTE 1