Integer data types can be specified as follows:
If a kind parameter is specified, the integer has the kind specified. If a kind parameter is not specified, integer constants are interpreted as follows:
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:
An unsigned constant is assumed to be nonnegative.
Integers are expressed in decimal values (base 10) by default. To specify a constant that is not in base 10, use the following syntax:
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.
Examples
The following examples show valid and invalid integer (base 10) constants:
Valid | |
0 | |
-127 | |
+32123 | |
47_2 | |
Invalid | Explanation |
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 for integers. |
The following integers (most of which are not base 10) 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'
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