C++中組合類的初始化：冒號語法（常數據成員和引用成員的初始化）

1. #include <iostream>
2. #include<string>
4. using namespace std;
5. class Student
6. {
7. int semesHours;
8. float gpa;
9. public:
10. Student(int i)
11. {
12. cout << "constructing student.\n";
13. semesHours = i;
14. gpa = 3.5;
15. }
16. ~Student()
17. {
18. cout << "~Student\n";
19. }
20. };
22. class Teacher
23. {
24. string name;
25. public:
26. Teacher(string p)
27. {
28. name = p;
29. cout << "constructing teacher.\n";
30. }
31. ~Teacher()
32. {
33. cout << "~Teacher\n";
34. }
35. };
37. class TutorPair
38. {
39. public:
40. TutorPair(int i, int j, string p) :
41. teacher(p), student(j)
42. {
43. cout << "constructing tutorpair.\n";
44. noMeetings = i;
45. }
46. ~TutorPair()
47. {
48. cout << "~TutorPair\n";
49. }
50. protected:
51. Student student;
52. Teacher teacher;
53. int noMeetings;
54. };
56. int main(int argc, char **argv)
57. {
58. TutorPair tp(5, 20, "Jane");
59. cout << "back in main.\n";
60. return 0;
61. }

1. constructing student.
2. constructing teacher.
3. constructing tutorpair.
4. back in main.
5. ~TutorPair
6. ~Teacher
7. ~Student

另外：構造函數初始化常數據成員和引用成員。

1. #include <iostream>
2. #include <string>
4. using namespace std;
6. class Student
7. {
8. public:
9. Student(int s, int &k) :
10. i(s), j(k)
11. {
12. } //不可以直接賦值
13. void p()
14. {
15. cout << i << endl;
16. cout << j << endl;
17. }
18. protected:
19. const int i;
20. int &j;
21. };
23. int main(int argc, char **argv)
24. {
25. int c = 123;
26. Student s(9818, c);
27. s.p();
29. return 0;
30. }

1. 9818
2. 123