类里面的static和函数指针的特殊事项

1. #include<iostream>
2. usingnamespacestd;
3. intprint(){
4. cout<<"YYYYYYYYY\n";
5. }
6. classtt{
7. public:
8. staticint(*pp)();
9. staticint*p;
10. intv(){
11. this->pp();//staticcanbeivokedbythis,but......
12. }
13. staticintvv(){
14. //this->pp();No,onlystaticmemberorfunccanbeevoked!
15. }
16. };
17. int(*tt::pp)()=print;//likethistoinitialise!
18. int*tt::p=NULL;//must1.*2.tt::and3.p
19. intmain(){
20. tta;
21. a.pp();
22. (*tt::pp)();
23. cout<<sizeof(tt)<<endl;//1
24. }
25. #include<iostream>
26. usingnamespacestd;
27. voidprint(){
28. cout<<"asdf\n";
29. }
30. classtt{
31. public:
32. void(*p)();
33. tt(){
34. p=&(::print);
35. }
36. inta(){
37. cout<<"aaaaafunction!\n";
38. }
39. };
40. typedefint(tt::*MM)();
41. intmain(){
42. cout<<sizeof(tt)<<endl;//4not1,void*pinclassttisaval,notafunction!sosizeofis4
43. tta;
44. a.p();
45. cout<<&tt::a<<endl;
46. //cout<<(int)&a.a<<endl;
47. MMmyf=&tt::a;
48. (a.*myf)();//likethis
49. }
50. #include<iostream>
51. usingnamespacestd;
52. classtt{
53. public:
54. staticinta;
55. };
56. inttt::a=10;
57. intmain(){
58. cout<<sizeof(tt)<<endl;//1,static,nomatteritisconstorpointerorreference!saveinstaticsection,notclass
59. //scope!
60. cout<<tt::a<<endl;
61. }
62. #include<iostream>
63. usingnamespacestd;
64. classtt{
65. public:
66. doublea;
67. charb;
68. virtualint_a(){}
69. virtualint_b(){}
70. };
71. intmain(){
72. cout<<sizeof(tt)<<endl;//Linux16,Windows24,andvptrinthebeginningclass!
73. //butalignofwindowsis8,becauseofthedouble,butalignoftheLinuxis4,evenif
74. //uuse#pragmapack(8),thealignisstill4BYTE!
75. }
76. #include<iostream>
77. usingnamespacestd;
78. classT{
79. public:
80. charaa;
81. doublei;
82. virtualinta(){}
83. };
84. intmain(){
85. //cout<<&(((T*)1)->aa)<<endl;//canuseitinWindows!LInux:can't
86. //gettheaa'saddr,togetthatthevptris
87. //atthebeginningortheendoftheclassortheclassobject!
88. T*a=newT;
89. cout<<(int)&(a->aa)<<endl;
90. cout<<(int)a<<endl;
91. 
    
92. cout<<sizeof(T)<<endl;
93. deletea;
94. }

其实，一些很变态的使用操作都在上面了，这里仅仅是一些很少用到的东西，注意拉！