Mô tả mối quan hệ giữa phần cứng và phần mềm. ◗ Xác định các loại khác nhau của phần mềm và chúng được sử dụng như thế nào. ◗ Xác định các thành phần phần cứng cốt lõi của một máy tính và giải thích mục đích của họ. ◗ Giải thích làm thế nào các thành phần phần cứng tương tác với nhau để thực hiện các chương trình và quản lý dữ liệu. | 184 CHAPTER 3 program statements requirements often involves an extended dialog with the client. The client may very well have a clear vision about what the program should do but this list of requirements does not provide enough detail. For example how many test scores should be processed Is this program intended to handle a particular class size or should it handle varying size classes Is the input stored in a data file or should it be entered interactively Should the average be computed to a specific degree of accuracy Should the output be presented in any particular format Let s assume that after conferring with the client we establish that the program needs to handle an arbitrary number of test scores each time it is run and that the input should be entered interactively. Furthermore the client wants the average presented to two decimal places but otherwise allows us the developer to specify the details of the output format. Now let s consider some design questions. Because there is no limit to the number of grades that can be entered how should the user indicate that there are no more grades We can address this situation in several possible ways. The program could prompt the user after each grade is entered asking if there are more grades to process. Or the program could prompt the user initially for the total number of grades that will be entered then read exactly that many grades. A third option When prompted for a grade the instructor could enter a sentinel value that indicates that there are no more grades to be entered. The first option requires a lot more input from the user and therefore is too cumbersome a solution. The second option seems reasonable but it forces the user to have an exact count of the number of grades to enter and therefore may not be convenient. The third option is reasonable but before we can pick an appropriate sentinel value to end the input we must ask additional questions. What is the range of valid grades What would be an .
