PGI Fortran Reference manual - The Portland Group

Fortran Data Typesto this rule is that an operation involving a COMPLEX*8 element and a REAL*8 elementproduces a COMPLEX*16 result. In this operation, the COMPLEX*8 element is converted toa COMPLEX*16 element, which consists of two REAL*8 elements, before the operation isperformed.In most cases, a logical expression will have a LOGICAL*4 result. In cases where the hardwaresupports LOGICAL*8 and if the expression is LOGICAL*8, the result may be LOGICAL*8.2.2. ConstantsA constant is an unchanging value that can be determined at compile time. It takes a formcorresponding to one of the data types. The PGI Fortran compilers support decimal (INTEGERand REAL), unsigned binary, octal, hexadecimal, character and Hollerith constants.The use of character constants in a numeric context, for example, in the right-hand side of anarithmetic assignment statement, is supported. These constants assume a data type that conformsto the context in which they appear.2.2.1. Integer ConstantsThe form of a decimal integer constant is:[s]d1d2...dn [ _ kind-parameter ]where s is an optional sign and di is a digit in the range 0 to 9. The optional _kind@parameteris a Fortran 90/95/2003 feature supported by PGFORTRAN, and specifies a supported kind. Thevalue of an integer constant must be within the range for the specified kind.The value of an integer constant must be within the range -2147483648 (-2 31 ) to 2147483647(2 31 - 1) inclusive. Integer constants assume a data type of INTEGER*4 and have a 32-bit storagerequirement.The –i8 compilation option causes all data of type INTEGER to be promoted to an 8 byteINTEGER. The –i8 option does not override an explicit data type extension size specifier, suchas INTEGER*4. The range, data type and storage requirement change if the –i8 flag is specified,although this flag is not supported on all x86 targets. With the –i8 flag, the range for integerconstants is -2 63 to (2 63 - 1)), and in this case the value of an integer constant must be withinthe range -9223372036854775808 to 9223372036854775807. If the constant does not fit in anINTEGER*4 range, the data type is INTEGER*8 and the storage requirement is 64 bits.Here are several examples of integer constants:+2-36437-36_SHORT369_I22.2.2. Binary, Octal and Hexadecimal ConstantsThe PGI compilers and Fortran 90/95/2003 support various types of constants in addition todecimal constants. Fortran allows unsigned binary, octal, or hexadecimal constants in DATAstatements. PGI compilers support these constants in DATA statements, and additionally, supportPGI Fortran Reference Guide 19