Patent ID: 6876774

Claim:
A data compression method for generating compressed data by performing a compression process on a data string to be compressed, comprising the steps of: setting a plurality of consecutive characters, which are contained in the data string, as a character string to be searched; allocating bits of a bit string representing said character string to two codewords to thereby generate a first searching codeword and a second searching codeword that is a complementary codeword to said first searching codeword; obtaining an array content from a first array table, in which said second codeword relating to past occurred character strings is previously stored, by using said first searching codeword relating to the set character string to be searched at present as an array address; collating the obtained array content with said second codeword; and obtaining information on past occurrence positions of said set character string from a second array table, in which past occurrence positions of character strings are previously entered, by using said first codeword as an array address when the array content matches with said second codeword.