DOCUMENT MANAGING APPARATUS, DATA COMPRESSING METHOD, AND DATA DECOMPRESSING METHOD

In a document managing apparatus for forming a compressed document file where a keyword retrieval is available, a first process operation and a second process operation are alternately executed. In the first process operation, when document data to be compressed is given, the respective characters are directly written into a compressed document file until an end control character string appears in this document data. In the second process operation, data obtained by coding the respective characters are written into the compressed document file until a start control character series appears in the document data. Also, in this document managing apparatus, a third process operation and a fourth process operation are alternately performed, when the compressed document file is restored. In the third process operation, the respective data (characters) are directly outputted until the end control character string appears in the data contained in the compressed document file. In the fourth process operation, the decoding operation is carried out until the start control character string appears in the restored result of the data contained in the compressed document file.