Data format is the format in which data is stored in files or records. Can be numerical value 、 character or Binary number Etc. It is described by data type and data length. [1] data type Is the same as that in the program variable Related data forms. Common data types can be divided into two categories. ① Simple type. Its data structure is very simple, with the same mathematical characteristics and the same computer internal representation. Its data logical structure is characterized by only one elementary term node. There are usually five basic simple types: integer type, real number type Boolean type , character types, and Pointer Type. ② Composite type. Or combination type or structure type , is a combination of simple types in some way. According to different construction methods, the following different data structure Type: 1) array Type. All components belong to the same type 2) Record type. Each component does not necessarily belong to the same type
3) Collection type. The value set it defines is of its base type Power set , that is, the base type range A set of all subsets of 4) file type . One of the components of the same type sequence This sequence specifies the natural order of the components The length of the data is measurable, usually using an eight bit binary array to form a byte , letters, numbers or other symbols on a keyboard ASCII Code representation, one byte can hold one ASCII code (including one bit Parity bit ). Computer memory Common use of Addressing The unit is in bytes. The communication transmission unit of a computer is also generally based on bytes. [2] The determination shall meet certain conditions: ① ensure all the information required for recording; ② Improve storage efficiency and ensure full utilization of storage space; ③ Standardized format to ensure relevant data processing system Data exchange between. according to data record Length is generally divided into fixed length format and variable length format. The records in the former file have the same length, while the length of the latter is determined by the length of the record value. 
