Creating an Array: Difference between revisions

In ANSI FORTRAN 77 or later, this is a default-indexing array declaration:

 

 

This array will have ten elements. Counting starts at 1.

If a zero-based array is needed, declare like this:

 

 

This mechanism can be extended to any numerical indices, and any of the up-to-seven-allowed number of dimensions (and of course to other data types than integers). For example:

 

 

will be an two-dimensional, 5x12-array of type REAL, where the first dimension can be addressed numerically as 25, 26, 27, 28 or 29 (and the second dimension as 1 .. 12).

 

In ISO Fortran 95 or later, arrays can also be initialized using a robust set of array constructors and array intrinsic functions.

real :: a(100) = 0 ! entire array initialized to ZERO

real :: b(9) = (/ 1,2,3,4,5,6,7,8,9 /) ! array constructor

print '(4F7.0)', e(i,:) ! print row I

end do

 

Output:

 

Here is a more interesting example showing a function that creates and returns a square identity matrix of order N:

contains

function identity(n)

! -- a scalar

end function identity

 

use matrixUtil

integer :: n

end do

deallocate(i)

 

Example run: