What is difference between sequential file and index file?
the index file is more sicurity checked and contains more information about the acess . for example An indexed file is a computer file with an index that allows easy random access to any record given its file key.The key must be such that it uniquely identifies a record. If more than one index is present the other ones are called alternate indexes.The COBOL language supports indexed files with the following command in the FILE CONTROL section. however a sequential file isA file that contains records or other elements that are stored in a chronological order based on account number or some other identifying data. In order to locate the desired data, sequential files must be read starting at the beginning of the file. A sequential file may be stored on a sequential access device such as magnetic tape or on a direct access device such as magnetic disk. Contrast with random-file.Read more: sequential-fileContent of sequential file can't be accessed directly while index file content can be accessed directly through pointer. Sequential file is time consuming in comparison with index file.Example: Index of book - index fileExample: Bundle of plates - sequential file