From 495272cff94e548a4da93926773598a7270b69a6 Mon Sep 17 00:00:00 2001 From: Jason Klebes Date: Wed, 25 Sep 2024 10:45:27 +0100 Subject: [PATCH] [fortran/en] Fixed overly long comment lines (#5126) * [haskell/de] Added missing comment line about index operator * [fortran/en] Fixed overly long comment lines Including minor rewording and rearranging. A comment was added at 'subroutine' --- fortran.html.markdown | 86 ++++++++++++++++++++++++++----------------- 1 file changed, 52 insertions(+), 34 deletions(-) diff --git a/fortran.html.markdown b/fortran.html.markdown index 83074073c5..299f99ba8a 100644 --- a/fortran.html.markdown +++ b/fortran.html.markdown @@ -30,7 +30,8 @@ program example ! declare a program called example. ! All declarations must come before statements and expressions. - implicit none ! prevents dynamic declaration of variables (recommended!) + implicit none ! prevents dynamic declaration of variables + ! Recommended! ! Implicit none must be redeclared in every function/program/module... ! IMPORTANT - Fortran is case insensitive. @@ -45,10 +46,14 @@ program example ! declare a program called example. complex :: w = (0, 1) ! sqrt(-1) character(len=3) :: month ! string of 3 characters. - real :: array(6) ! declare an array of 6 reals. - real, dimension(4) :: arrayb ! another way to declare an array. - integer :: arrayc(-10:10) ! an array with a custom index. - real :: array2d(3, 2) ! multidimensional array. + ! declare an array of 6 reals. + real :: array(6) + ! another way to declare an array. + real, dimension(4) :: arrayb + ! an array with a custom index -10 to 10 (inclusive) + integer :: arrayc(-10:10) + ! A multidimensional array. + real :: array2d(3, 2) ! The '::' separators are not always necessary but are recommended. @@ -76,8 +81,8 @@ program example ! declare a program called example. ! Assignment & Arithmetic ! ======================= - - Z = 1 ! assign to variable z declared above (case insensitive). + + Z = 1 ! assign to variable z declared above j = 10 + 2 - 3 a = 11.54/(2.3*3.1) b = 2**3 ! exponentiation @@ -86,7 +91,7 @@ program example ! declare a program called example. ! =================================== ! Single-line if statement - if (z == a) b = 4 ! condition always need surrounding parentheses. + if (z == a) b = 4 ! conditions always need parentheses. if (z /= a) then ! z not equal to a ! Other symbolic comparisons are < > <= >= == /= @@ -98,13 +103,13 @@ program example ! declare a program called example. b = 5 ! execution block must be on a new line. else b = 10 - end if ! end statement needs the 'if' (or can use 'endif'). + end if ! end statement needs the 'if' if (.NOT. (x < c .AND. v >= a .OR. z == z)) then ! boolean operators. inner: if (.TRUE.) then ! can name if-construct. b = 1 end if inner ! then must name endif statement. - end if + endif ! 'endif' is equivalent to 'end if' i = 20 select case (i) @@ -128,16 +133,16 @@ program example ! declare a program called example. j = -1 end select monthly - do i = 2, 10, 2 ! loops from 2 to 10 (inclusive) in increments of 2. + do i = 2, 10, 2 ! loops from 2 to 10 (inclusive) in steps of 2. innerloop: do j = 1, 3 ! loops can be named too. exit ! quits the loop. end do innerloop cycle ! jump to next loop iteration. end do - ! Goto statement exists but it is heavily discouraged though. + ! Goto statement exists but it is heavily discouraged. goto 10 - stop 1 ! stops code immediately (returning specified condition code). + stop 1 ! stops the program, returns condition code 1. 10 j = 201 ! this line is labeled as line 10 ! Arrays @@ -209,8 +214,12 @@ program example ! declare a program called example. ! we can have multiple format specifications. print "(I5,F6.2,E6.2)", 120, 43.41, 43.41 - print "(3I5)", 10, 20, 30 ! 3 repeats of integers (field width = 5). - print "(2(I5,F6.2))", 120, 43.42, 340, 65.3 ! repeated grouping of formats. + + ! 3 repeats of integers (field width = 5). + print "(3I5)", 10, 20, 30 + + ! repeated grouping of formats. + print "(2(I5,F6.2))", 120, 43.42, 340, 65.3 ! We can also read input from the terminal. read (*, *) v @@ -225,8 +234,9 @@ program example ! declare a program called example. ! To read a file. open (newunit=m, file="records.txt", status="old") - ! The file is referred to by a 'new unit number', an integer that the compiler - ! picks for you. + ! The file is referred to by a 'new unit number', + ! an integer that the compiler picks for you. + read (unit=m, fmt="(3F10.2)") a, b, c close (m) @@ -241,7 +251,7 @@ program example ! declare a program called example. call cpu_time(v) ! sets 'v' to a time in seconds. k = ior(i, j) ! bitwise OR of 2 integers. v = log10(x) ! log base 10. - i = floor(b) ! returns the closest integer less than or equal to x. + i = floor(b) ! converts b to integer by rounding down. v = aimag(w) ! imaginary part of a complex number. ! Functions & Subroutines @@ -252,7 +262,7 @@ program example ! declare a program called example. call routine(a, c, v) ! subroutine call. - ! A function takes a list of input parameters and returns a single value. + ! A function takes several input parameters and returns a single value. ! However the input parameters may still be modified and side effects ! executed. @@ -261,21 +271,22 @@ program example ! declare a program called example. ! Function calls can also be evoked within expressions. print *, func2(3, 2, k) - ! A pure function is a function that doesn't modify its input parameters - ! or cause any side-effects. + ! A pure function is a function that doesn't modify its input + ! parameters or cause any side-effects. m = func3(3, 2, k) -contains ! Zone for defining sub-programs internal to the program. +contains ! Start defining the program's internal procedures: ! Fortran has a couple of slightly different ways to define functions. integer function func(a, b, c) ! a function returning an integer value. - ! implicit none ! subvariable fields can no longer declare implicit none - integer, intent(in) :: a, b, c ! type of input parameters defined inside the function. + ! implicit none ! - no longer used in subvariable fields + integer, intent(in) :: a, b, c ! type of input parameters + ! the return variable defaults to the function name. if (a >= 2) then - func = a + b + c ! the return variable defaults to the function name. - return ! can return the current value from the function at any time. + func = a + b + c + return ! returns the current value at 'func' end if func = a + c @@ -286,24 +297,29 @@ contains ! Zone for defining sub-programs internal to the pro integer, intent(in) :: a, b ! can declare and enforce that variables !are not modified by the function. integer, intent(inout) :: c - integer :: f ! function return type declared inside the function. - integer :: cnt = 0 ! GOTCHA - initialisation implies variable is - !saved between function calls. + integer :: f + ! function return type declared inside the function. + integer :: cnt = 0 ! GOTCHA - + ! assigning a value at initalization + ! implies that the variable is + ! saved between function calls. f = a + b - c - c = 4 ! altering the value of an input variable. + c = 4 ! changing value of input variable c. cnt = cnt + 1 ! count number of function calls. end function func2 - pure function func3(a, b, c) ! a pure function can have no side-effects. + pure function func3(a, b, c) ! a pure function has no side-effects. integer, intent(in) :: a, b, c integer :: func3 func3 = a*b*c end function func3 - + + ! a subroutine does not return anything, + ! but can change the value of arguments. subroutine routine(d, e, f) real, intent(inout) :: f real, intent(in) :: d, e @@ -312,7 +328,8 @@ contains ! Zone for defining sub-programs internal to the pro end subroutine routine -end program example ! End of Program Definition ----------------------- +end program example +! End of Program Definition ----------------------- ! Functions and Subroutines declared externally to the program listing need ! to be declared to the program using an Interface declaration (even if they @@ -350,7 +367,8 @@ module fruity use fruit, only: apple, pear ! use apple and pear from fruit module. implicit none ! comes after module imports. - private ! make things private to the module (default is public). + ! By default all module data and functions will be public + private ! Instead set default to private ! Declare some variables/functions explicitly public. public :: apple, mycar, create_mycar ! Declare some variables/functions private to the module (redundant here).