FORTRAN Reference Manual

Language Elements
FORTRAN Reference Manual—528615-001
2-9
Implicit and Explicit Typing
Implicit and Explicit Typing
By default, FORTRAN interprets symbolic names that begin with the letters I, J, K, L,
M, and N as type integer and interprets names that begin with any other letter as type
real. You can override the default type by using one of the following type declaration
statements:
INTEGER*2
INTEGER*4
INTEGER*8
REAL
DOUBLE PRECISION
LOGICAL
COMPLEX
CHARACTER
The INTEGER type declaration, without an explicit length, refers to the prevailing
integer type as determined by an INTEGER*2, INTEGER*4, or INTEGER*8 compiler
directive. In the absence of such a directive, INTEGER means INTEGER*2. Similarly,
Figure 2-1. FORTRAN Data Storage
LOGICAL*4
WORDS
12
34
COMPLEX
LOGICAL*2
REAL*4
INTEGER*4
DOUBLE
PRECISION
INTEGER*8
INTEGER*2
REAL
VST0201.vsd
IMAGINARY