用C语言编写软件完成以下任务： 某家建材商店去年7月的销售业绩清单存储在文件file28.txt,格式为：售贷员编号，售贷员姓名，销售日期，销售售额-C language used to write software to accomplish the following tasks: a building materials store in July last year, sales list stored in file file28.txt, format: the sale of