Array Constructors

Array constructors are used to give arrays or sections of arrays specific values. An array constructor is a comma separated list of scalar expressions delimited by (/ and /). The results of the expressions are placed into the array in array element order with any type conversions being performed in the same manner as for regular assignment. The constructor must be of the correct length for the array, in other words, the section and the constructor must conform.

For example,

     IMPLICIT NONE
     INTEGER, DIMENSION(1:10)  :: ints
     CHARACTER(len=5), DIMENSION(1:3) :: colours
     REAL, DIMENSION(1:4)      :: heights
     heights = (/5.10, 5.6, 4.0, 3.6/)
     colours = (/'RED  ','GREEN','BLUE '/)
     ! note padding so strings are 5 chars
     ints    = (/ 100, (i, i=1,8), 100 /)
      ...
    END

The array and its constructor must conform.

Notice that all strings in the constructor for colours are 5 characters long. This is because the string within the constructor must be the correct length for the variable.

(i, i=1,8) is an implied-DO specifier and may be used in constructors to specify a sequence of constructor values. There may be any number of separate implied DO s which may be mixed with other specification methods. In the above example the vector ints will contain the values (/ 100, 1, 2, 3, 4, 5, 6, 7, 8, 100 /). Note the format of the implied DO: a DO-loop index specification surrounded by parentheses.

There is a restriction that only one dimensional constructors are permitted, for higher rank arrays the RESHAPE intrinsic must be used to modify the shape of the result of the RHS so that it conforms to the LHS:

    INTEGER, DIMENSION(1:3,1:4) :: board
    board = RESHAPE((/11,21,31,12,22,32,13,23,33,14,24,34/), (/3,4/))

The values are specified as a one dimensional constructor and then the shape is modified to be a array which conforms with the declared shape of board.

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