# Overloaded Operators
## `OPERATOR(.AND.)` -- Specify Dimension Extent
| Synopsis |
|:--|
| `ARGS = LEN .AND. IS_UNLIM` |
| Class |
|:--|
| Generic elemental function. |
| Description |
|:--|
| Create a dimension argument that combines an extent with its unlimited status. Use the result as the right operand of `.DIM.`. |
| Arguments |
|:--|
| `LEN``INTEGER(INT32) OR INTEGER(INT64), INTENT(IN)`
Dimension extent. |
| `IS_UNLIM``LOGICAL, INTENT(IN)`
Whether the dimension is unlimited. |
| Return |
|:--|
| `ARGS``type(dimension_argument_type)`
Dimension extent and unlimited status for use with `.DIM.`. |
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*
- Example
*
-
```fortran
use, non_intrinsic :: nc4f
implicit none (type, external)
type(dimension_type) :: time
integer :: length
logical :: is_unlimited
length = 24
is_unlimited = .true.
time = "time" .dim. (length .and. is_unlimited)
```
:::
## `OPERATOR(.ATT.)` -- Construct an Attribute
| Synopsis |
|:--|
| `ATT = NAME .ATT. VALUE` |
| Class |
|:--|
| Generic function. |
| Description |
|:--|
| Construct an `attribute_type` from a name and a scalar or rank-one supported NetCDF value. |
| Arguments |
|:--|
| `NAME``CHARACTER(LEN=*), INTENT(IN)`
Attribute name. |
| `VALUE``TYPE(INTEGER(INT8, INT16, INT32, INT64), REAL(REAL32, REAL64), CHARACTER), RANK(0:1), INTENT(IN)`
Supported numeric scalar or vector, or a character scalar. |
| Return |
|:--|
| `ATT``type(attribute_type)`
Constructed attribute. |
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- Example
*
-
```fortran
use, non_intrinsic :: nc4f
implicit none (type, external)
type(attribute_type) :: units
character(len=*), parameter :: unit_name = "K"
units = "units" .att. unit_name
```
:::
## `OPERATOR(.DIM.)` -- Construct a Dimension
| Synopsis |
|:--|
| `DIM = NAME .DIM. LEN`
`DIM = NAME .DIM. ARGS` |
| Class |
|:--|
| Generic elemental function. |
| Description |
|:--|
| Construct a limited dimension from an extent, or a limited or unlimited dimension from an argument created by `.AND.`. |
| Arguments |
|:--|
| `NAME``CHARACTER(LEN=*), INTENT(IN)`
Dimension name. |
| `LEN``INTEGER(INT32) OR INTEGER(INT64), INTENT(IN)`
Extent of a limited dimension. |
| `ARGS``TYPE(DIMENSION_ARGUMENT_TYPE), INTENT(IN)`
Extent and unlimited status created by `.AND.`. |
| Return |
|:--|
| `DIM``type(dimension_type)`
Constructed limited or unlimited dimension. |
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*
- Example
*
-
```fortran
use, non_intrinsic :: nc4f
implicit none (type, external)
type(dimension_type) :: latitude
integer :: length
length = 181
latitude = "latitude" .dim. length
```
:::
## `OPERATOR(.EXISTS.)` -- Test an Error Result
| Synopsis |
|:--|
| `FAILED = .EXISTS. ERR` |
| Class |
|:--|
| Pure elemental function. |
| Description |
|:--|
| Return true when an `error_type` represents a failed operation. |
| Arguments |
|:--|
| `ERR``TYPE(ERROR_TYPE), INTENT(IN)`
Operation result to test. |
| Return |
|:--|
| `FAILED``logical`
True when the error result represents a failed operation. |
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*
- Example
*
-
```fortran
use, non_intrinsic :: nc4f
implicit none (type, external)
type(error_type) :: error
if (.exists. error) print *, error%msg
```
:::
## `OPERATOR(/=)` -- Compare Model Objects
| Synopsis |
|:--|
| `IS_DIFF = X /= Y` |
| Class |
|:--|
| Generic elemental function. |
| Description |
|:--|
| Return true when two attributes, dimensions, or variables are not equal. |
| Arguments |
|:--|
| `X``TYPE(ATTRIBUTE_TYPE, DIMENSION_TYPE, VARIABLE_TYPE), INTENT(IN)`
First model object. |
| `Y``SAME TYPE AS X, INTENT(IN)`
Second model object. |
| Return |
|:--|
| `IS_DIFF``logical`
True when the model objects differ. |
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- Example
*
-
```fortran
use, non_intrinsic :: nc4f
implicit none (type, external)
type(dimension_type) :: observed, expected
if (observed /= expected) print *, "Values differ."
```
:::
## `OPERATOR(==)` -- Compare Model Objects
| Synopsis |
|:--|
| `IS_EQUAL = X == Y` |
| Class |
|:--|
| Generic elemental function. |
| Description |
|:--|
| Return true when two attributes, dimensions, or variables are equal. |
| Arguments |
|:--|
| `X``TYPE(ATTRIBUTE_TYPE, DIMENSION_TYPE, VARIABLE_TYPE), INTENT(IN)`
First model object. |
| `Y``SAME TYPE AS X, INTENT(IN)`
Second model object. |
| Return |
|:--|
| `IS_EQUAL``logical`
True when the model objects are equal. |
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*
- Example
*
-
```fortran
use, non_intrinsic :: nc4f
implicit none (type, external)
type(dimension_type) :: reference, candidate
if (reference == candidate) print *, "Values match."
```
:::