An array constructor [a, b, c] initializes a fixed-shape array. sum adds all elements at once.

Program

Play the program to build a 4-element array and sum it.

arrays.f90
program arrays
    implicit none
    integer :: nums(4)
    integer :: total
    nums = [1, 2, 3, 4]
    total = sum(nums)
    print '(I0)', total
end program arrays
array constructor `[1, 2, 3, 4]` builds a rank-1 array.
sum `sum(nums)` reduces an array to one scalar.
one-based index Fortran arrays start at index 1 by default.