电话计费系统，具有以下功能：计费功能。根据存放在源数据文件中的通话记录和长途费率文件对每一条通话记录计算其通话费用，并将结果保存在费用文件中。话费查询。输入一个电话号码，从费用文件中统计该电话号码的所有本地话费、长途话费，并从用户文件中查找其用户名。话单查询。输入一个电话号码，查询并在屏幕显示该用户的所有通话记录-Telephone billing system, has the following functions: billing functions. According to the source data files stored in the long distance call records and document the rate of a call record for each call to calculate their costs, and the results stored in the cost of document. Inquiry calls. Enter a phone number, statistics from the cost of paper all the phone numbers of local calls, long distance calls, and documents from the user to find their user name. If a single query. Enter a phone number, query and display all the user' s phone records