022. Functions should be pure and have intent(in) arguments

topic: Procedures

intent(in) arguments cannot be changed. pure = no side effects. Use subroutine instead for a procedure with side effects.

func.f90 | | |

print *, area(3., 4.)  ! 12

contains

real pure function area(length, width)
   real, intent(in) :: length, width
   area = length*width
end function area

end

Output1

   12.0000000    

real in the function definition line indicates the type of the return value. By default, the value corresponding to a variable with the same name as the function is returned (here area).

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Demo of a Fortran function. Intent(in) arguments
cannot be changed. Function arguments should be intent(in). Pure = no side-effects.

print*,area(3.,4.) ! 12
contains
real pure function area(length,width)
real, intent(in) :: length,width
area = length*width
end function area
end

— FortranTip (@fortrantip) December 19, 2021

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Compiled using GNU Fortran (Ubuntu 11.3.0-1ubuntu1~22.04) 11.3.0 with no flags