Accelerated C++：通过示例进行编程实践——练习解答（第9章）

[b]我的Github地址：https://github.com/lanbeilyj/Accerlerated-C-plus-plus
[/b]

9-0. Compile, execute, and test the programs in this chapter.

Ans：见Github。

9-1. Reimplement the

Student_info

class so that it calculates the final

grade

when reading the student's record, and stores that grade in the object. Reimplement the

grade

function to use this precomputed value.

Ans：见Github。

9-2. If we define the

name

function as a plain, non

const

member function, what other functions in our system must change and why?

Ans：我们仅仅需要修改函数 compare()的参数类型即可：将原先的bool compare(const Student_info& x,const Student_info& y)改为

bool compare(Student_info x,Student_info y)

Tips：const对象不可以调用const成员函数函数；

为什么又把 Student_info& 改成了Student_info x？

因为sort(students.begin(),students.end(),compare)，函数中传递给compare是一个const对象，因为不能用一个const对象来初始化一个非const引用，故需要修改为传值形式。

9-3. Our

grade

function was written to throw an exception if a user tried to calculate a grade for a

Student_info

object whose values had not yet been read. Users who care are expected to catch this exception. Write a program
that triggers the exception but does not catch it. Write a program that catches the exception.

Ans：见Github。

9-4. Rewrite your program from the previous exercise to use the

valid

function, thereby avoiding the exception altogether.

Ans：见Github。

9-5. Write a class and associated functions to generate grades for students who take the course for pass/fail credit. Assume that only the midterm and final grades matter, and that a student passes with an average exam score greater than 60. The
report should list the students in alphabetical order, and indicate P or F as the grade.

Ans：见Github。

9-6. Rewrite the grading program for the pass/fail students so that the report shows all the students who passed, followed by all the students who failed.

Ans：见Github。

9-7. The

read_hw

function §4.1.3/57 solves a general problem (reading a sequence of values into a

vector

) even though its name suggests that it should be part of the implementation of

Student_info

. Of course,
we could change its name—but suppose, instead, that you wanted to integrate it with the rest of the

Student_info

code, in order to clarify that it was not intended for public access despite its apparent generality? How would you do so?

Ans：见Github。