Integer Constants

An integer constant is a whole number with no decimal point. It can have a leading sign and is interpreted as a decimal number.

Integer constants take the following form:

[s]n[n...][ _k]

`s`	Is a sign; required if negative (-), optional if positive (+).
`n`	Is a decimal digit (0 through 9). Any leading zeros are ignored.
`k`	Is the optional kind parameter: 1 for INTEGER(1), 2 for INTEGER(2), 4 for INTEGER(4), or 8 for INTEGER(8). It must be preceded by an underscore ( _ ).

An unsigned constant is assumed to be nonnegative.

Integer constants are interpreted as decimal values (base 10) by default. To specify a constant that is not in base 10, use the following extension syntax:

[s] [[base] #] nnn...

s

Is an optional plus (+) or minus (-) sign.

base

Is any constant from 2 through 36.

If base is omitted but # is specified, the integer is interpreted in base 16. If both base and # are omitted, the integer is interpreted in base 10.

For bases 11 through 36, the letters A through Z represent numbers greater than 9. For example, for base 36, A represents 10, B represents 11, C represents 12, and so on, through Z, which represents 35. The case of the letters is not significant.

Note that compiler option integer-size can affect INTEGER data.

Examples

Valid Integer (base 10) Constants
0
-127
+32123
47_2

Invalid Integer (base 10) Constants
9999999999999999999	Number too large.
3.14	Decimal point not allowed; this is a valid REAL constant.
32,767	Comma not allowed.
33_3	3 is not a valid kind type for integers.

The following seven integers are all assigned a value equal to 3,994,575 decimal:

I = 2#1111001111001111001111

m = 7#45644664

J = +8#17171717

K = #3CF3CF

n = +17#2DE110

L = 3994575

index = 36#2DM8F

You can use integer constants to assign values to data. The following table shows assignments to different data and lists the integer and hexadecimal values in the data:

Fortran Assignment Integer Value in Data Hexadecimal Value in Data

LOGICAL(1)X

INTEGER(1)X

X = -128 -128 Z'80'

X = 127 127 Z'7F'

X = 255 -1 Z'FF'

LOGICAL(2)X

INTEGER(2)X

X = 255 255 Z'FF'

X = -32768 -32768 Z'8000'

X = 32767 32767 Z'7FFF'

X = 65535 -1 Z'FFFF'

Integer Constants

Examples

See Also