PGI Fortran Reference manual - The Portland Group

Chapter 2.FORTRAN DATA TYPESEvery Fortran element and expression has a data type. The data type of an element may beimplicit in its definition or explicitly attached to the element in a declaration statement. Thissection describes the Fortran data types and constants that are supported by the PGI Fortrancompilers.Fortran provides two kinds of data types, intrinsic data types and derived data types. Typesprovided by the language are intrinsic types. Types specified by the programmer and built fromthe intrinsic data types are called derived types.2.1. Intrinsic Data TypesFortran provides six different intrinsic data types, listed in Table 9 and Table 11 show variationsand different KIND of intrinsic data types supported by the PGI Fortran compilers.Table 9 Fortran Intrinsic Data TypesData TypeINTEGERREALDOUBLE PRECISIONLOGICALCOMPLEXCHARACTERValueAn integer number.A real number.A double precision floating point number, real number, taking up two numeric storage unitsand whose precision is greater than REAL.A value which can be either TRUE or FALSE.A pair of real numbers used in complex arithmetic. Fortran provides two precisions forCOMPLEX numbers.A string consisting of one or more printable characters.2.1.1. Kind ParameterThe Fortran 95 KIND parameter specifies a precision for intrinsic data types. The KINDparameter follows a data type specifier and specifies size or type of the supported data type. AKIND specification overrides the length attribute that the statement implies and assigns a specificPGI Fortran Reference Guide 16