Method for constructing LDPC codes and codes

The invention discloses a method for generating LDPC codes. The method comprises the following steps that: step one, the size of a check matrix of the LDPC codes is set, wherein the check matrix is divided into an information portion and a check portion, wherein the check portion is obtained through dual diagonal matrix interweaving; step two, the information portion is divided into a plurality of sub information matrixes, wherein each sub information matrix comprise a plurality of circulatory arrays, and the column degree of each sub information matrix is determined, wherein the column degree is the number of non-zero circulatory arrays contained in the sub information matrix; step three, the positions of the non-zero circulatory arrays of each sub information matrix are determined; and step four, the offset of the non-zero circulatory arrays of each sub information matrix is determined. According to the method of the invention, on the one hand, the minimum distance of the codes is decreased through adopting