HDFql Reference Manual v2.6.0
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Manual/6 Language/6.1 Data Types

6.1.13UNSIGNED VARTINYINT

The HDFql UNSIGNED VARTINYINT data type stores values between 0 and 255 and occupies 1 byte in memory (per element). It represents the data type of an HDF5 (variable-length) H5T_NATIVE_UCHAR dataset/attribute or of a result set that stores variable-length elements of this type (which can be retrieved using the HDFQL_CURSOR_GET_UNSIGNED_TINYINT and HDFQL_SUBCURSOR_GET_UNSIGNED_TINYINT functions when working with cursors). Depending on the programming language supported by HDFql, the UNSIGNED VARTINYINT data type is represented by:

  • In C, the “unsigned char” data type.
  • In C++, the “unsigned char” data type.
  • In Java18, the “ArrayList<Byte>” class.
  • In Python, the “uint8” NumPy data type.
  • In C#, the “Byte” data type (or corresponding alias “byte”).
  • In Fortran19, the “INTEGER(KIND = 1)” data type.
  • In R20, the “integer” data type.
  • In MATLAB, the “uint8” data type.

Notes

  1. By design, Java does not support unsigned data types. Therefore, the programmer is responsible for converting a signed number to its equivalent unsigned representation in Java. ↩
  2. Although there have been some efforts to introduce unsigned data types in Fortran, none are currently standardized. Therefore, the programmer is responsible for converting a signed number to its equivalent unsigned representation in Fortran. ↩
  3. By design, R does not provide a data type that stores values between 0 and 255 using exactly 1 byte of memory. As a substitute, the R “integer” data type may be used, at the cost of increased memory usage (as it occupies 4 bytes of memory) and lower performance (as byte alignment must be performed by HDFql). ↩