Intrinsic Data Types

Intel® Fortran expects numeric data to be in native little endian order, in which the least-significant, right-most zero bit (bit 0) or byte has a lower address than the most-significant, left-most bit (or byte). For information on using nonnative big endian and VAX* floating-point formats, see Converting Unformatted Numeric Data.

The symbol :A in any figure specifies the address of the byte containing bit 0, which is the starting address of the represented data element.

The following table lists the intrinsic data types used by Intel Fortran, the storage required, and valid ranges. For example, the declaration INTEGER(4) is the same as INTEGER(KIND=4) and INTEGER*4.

Data Type 

Storage 

Description 

BYTE
INTEGER(1)

1 byte
(8 bits)

A BYTE declaration is a signed integer data type equivalent to INTEGER(1).

INTEGER

See INTEGER(2), INTEGER(4), and INTEGER(8).

Signed integer, either INTEGER(2), INTEGER(4), or INTEGER(8). The size is controlled by the -integer_size nn compiler option. The default is -integer_size 32 (INTEGER(4)).

INTEGER(1)

1 byte
(8 bits)

Signed integer value from -128 to 127.

INTEGER(2)

2 bytes
(16 bits)

Signed integer value from -32,768 to 32,767.

INTEGER(4)

4 bytes
(32 bits)

Signed integer value from -2,147,483,648 to 2,147,483,647.

INTEGER(8)

8 bytes
(64 bits)

Signed integer value from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807.

REAL(4)
REAL

4 bytes
(32 bits)

Single-precision real floating-point values in IEEE S_floating format ranging from 1.17549435E-38 to 3.40282347E38. Values between 1.17549429E-38 and 1.40129846E-45 are denormalized (subnormal).

REAL(8)
DOUBLE PRECISION

8 bytes
(64 bits)

Double-precision real floating-point values in IEEE T_floating format ranging from 2.2250738585072013D-308 to 1.7976931348623158D308. Values between 2.2250738585072008D-308 and 4.94065645841246544D-324 are denormalized (subnormal).

REAL(16)
EXTENDED PRECISION

16 bytes (128 bits)

Extended-precision real floating-point values in IEEE-style  X_floating format ranging from  6.4751751194380251109244389582276465524996Q-4966 to 1.189731495357231765085759326628007016196477Q4932.

COMPLEX(4)
COMPLEX

8 bytes
(64 bits)

Single-precision complex floating-point values in a pair of IEEE S_floating format parts: real and imaginary. The real and imaginary parts each range from 1.17549435E-38 to 3.40282347E38. Values between 1.17549429E-38 and 1.40129846E-45 are denormalized (subnormal).

REAL(16)
EXTENDED PRECISION

16 bytes (128 bits)

Extended-precision real floating-point values in IEEE-style  X_floating format ranging from  6.4751751194380251109244389582276465524996Q-4966 to 1.189731495357231765085759326628007016196477Q4932

COMPLEX(8)
DOUBLE COMPLEX

16 bytes (128 bits)

Double-precision complex floating-point values in a pair of IEEE T_floating format parts: real and imaginary. The real and imaginary parts each range from 2.2250738585072013D-308 to 1.7976931348623158D308. Values between 2.2250738585072008D-308 and 4.94065645841246544D-324 are denormalized (subnormal).

COMPLEX(16)
EXTENDED PRECISION

32 bytes (256 bits)

Extended-precision complex floating-point values in a pair of IEEE-style X_floating format parts: real and imaginary. The real and imaginary parts each range from 6.4751751194380251109244389582276465524996Q-4966 to 1.189731495357231765085759326628007016196477Q4932.

LOGICAL

See LOGICAL(2), LOGICAL(4), and LOGICAL(8).

Logical value, either LOGICAL(2), LOGICAL(4), or LOGICAL(8). The size is controlled by the -integer_size nn compiler option. The default is -integer_size 32 (LOGICAL(4)).

LOGICAL(1)

1 byte
(8 bits)

Logical values .TRUE. or .FALSE.

LOGICAL(2)

2 bytes
(16 bits)

Logical values .TRUE. or .FALSE.

LOGICAL(4)

4 bytes
(32 bits)

Logical values .TRUE. or .FALSE.

LOGICAL(8)

8 bytes
(64 bits)

Logical values .TRUE. or .FALSE.

CHARACTER

1 byte (8 bits) per character

Character data represented by character code convention. Character declarations can be in the form CHARACTER(LEN=n) or CHARACTER*n, where n is the number of bytes or n is (*) to indicate passed-length format.

HOLLERITH

1 byte (8 bits) per Hollerith character

Hollerith constants.

In addition, you can define binary (bit) constants as explained in the Language Reference.

The following sections discuss the intrinsic data types in more detail: