If I understand correctly, any line that starts with C in column 1 is automatically a comment. So why do some code samples I see start the comment text at column 7? Is this just to make all text line up a little nicer, or was it required by some compilers?
Where the text of the comments start is completely irrelevant to the compiler, the compiler just ignores the line or the punch card.
It is just up to the programmer to format the comments based on the reasons that made him/her to create such comment. Often, programmers will want the comments to be somehow aligned, but it is not necessary.
For example, if a line of code that contained a numeric label is commented out, it will often start earlier than column 7.
Related
In the code below, the lines after the comment line start with *:
C REF: LANDOLT-B\RNSTEIN 2A-CP.209
* DMUACD=+0.0020*XCOS(DEL)-0.0044*XSIN(ALP)
* DMUACD=+0.0020*XCOS(DEL)-0.0044*XSIN(ALP)*xcos(del)
* DMUD=-0.0044*XCOS(ALP)
What does these lines mean?
In fixed-form Fortran (where the statement begins in column 7 and C in column 1 indicates a comment), an asterisk in column 1 also indicates a comment. In the snippet you have posted, all four lines are commented out, though different comment indicators are used, which certainly can be confusing. The asterisks could have been replaced with C for the same meaning.
As of Fortran 90, an exclamation point in column 1 also indicates a comment line (in both fixed and free form.)
Now, if the asterisk had been in column 6, it would have meant a continued line (any non-blank character other than the digit zero there would mean the same thing.) Vladimir (and "High Performance Mark") initially thought you were asking about that.
For more on source form, see my post Doctor Fortran in "Source Form Just Wants to be Free"
The time of day that you have missed. Recently I began to study the expressive expressions, but the task before me is too complicated.
I think many people need the ability to quickly format texts of almost any type. Problem is not easy and I hope to get a solution to this problem from professionals.
If you use a limited breakdown for each line, then only large lines are broken which is much better. That is, to break only those lines that are larger than a certain size and which are more or less evenly broken Correct formatting of the text is quite Difficult to take into account a lot, I will go out for a long time. As you can see, there are small lines and they have to be sent back by connecting the previous line, but the problem is. And again have to apply formatting. But it is unclear whether this new formatting will create new problems.
All this is write in the macro via notepad ++ one after another and use.
However, it is necessary to solve the most important problems:
It is important to
I want to immediately note: textFX does not offer. My attempts to write a macro with textFX (including attempts with 75 or a number from the clipboard failed, the text was written with unreadable code), I sent a corresponding message to the site notepad ++ a day ago
Use a regular point also do not offer. The fact is that notepad ++ macro does not understand the point of replacing the indentation with spaces by default 4pcs. (Yes, the macro must also indent the text, but this is all right)
About soft wordwrap (not formatted just click) is also not worth talking about.
inscrease line indent 2-4
split lines
descrease line indet 2-4
^(.?)$\s+?^(?=.^\1$) null
2017 (\d+:\d+) 17
subscribe .+$ null
(^.{1,30}$)\R \1
\r\r\n \n
^ spaces\1
i create macro and solved more problems
I have little knowledge of the Fortran language. I have come across some programs written in the 90s (see attached snapshot showing just a portion of a long script).
I'd like to know what kind of compiler is appropriate to execute such codes? I have installed gfortran-4.2.3 on my mac. I'm also not sure about the indentation in the attached code: if C (comment) is at column 1, does the main code start at column 9 or 7? what about the position of numbers placed in between referred by GO TO?
This is not Fortran 90. This is Fortran 77.
That said, gfortran is able to compile this code. Make sure that the file extension for the file is .f so that gfortran realises it's fixed-form.
The C needs to be in the first column, the numbers that you reference are labels, they can be between column 1 and 5. The asterisk at line 198 is a continuation character, meaning that this should be treated as part of the previous line. It must be in column 6. Everything else needs to be between columns 7 and 72 (inclusive)
Oh, and the 3-digit numbers at the very beginning are line numbers, and must not be in the source code.
Edited to add: Since you have to type it all again anyway, you might as well make it free-form:
Replace the C in the first column with !, and change the way continuation lines are marked: Turn this:
write (*, *) "This is some long text,
* which doesn't fit into a line"
Into this:
write(*, *) "This is some long text, " // &
"which doesn't fit into a line"
Everything else can stay like it is. (You can now use proper indentation, too!)
New Edit
So you've pasted the code that you wrote and the error messages, so I'm replying to that now.
In Fixed Form, any character past column 72 is ignored. You have a few lines with long strings, where the terminating quotation mark is in that ignored region.
Make sure that no line exceeds the 72nd row.
I'm trying to write some C++ in Sublime Text 2. If I begin a line with a double forward slash (//) the text in that line grays out as if it were commented out, but it causes a build error when I compile, so clearly it isn't. If I begin the line with a pound sign (#) that line is commented out but doesn't change in appearance. I want to be able to tell what lines are comments and what lines are actually part of my program. How is this done?
In c++ comments look like this
// one line comment or
/* comment
over multiple
lines */
If your compiler is not recognizing these, chances are, it's not compiling c++. This seems even more likely seeing how lines beginning with # will be ignored like you'd expected for some other languages (for example python)
Make sure to check what the "build" button in your IDE actually calls/does.
You can try this:
/*
I am a comment!
I am another comment!
*/
I hope this helps.
I have looked at the following question:
How to comment out a block of Python code in Vim
But that does not seem to work for me. How do I comment code easily without resorting to plugins/scripts?
Use ctrl-V to do a block selection and then hit I followed by //[ESC].
Alternatively, use shift-V to do a line-based select and then type :s:^://[Enter]. The latter part could easily go into a mapping. eg:
:vmap // :s:^://<CR>
Then you just shift-V, select the range, and type // (or whatever you bind it to).
You can add this to your .vimrc file
map <C-c> :s/^/\/\//<Enter>
Then when you need to comment a section just select all lines (Shift-V + movement) and then press CtrlC.
To un-comment you can define in a similar way
map <C-u> :s/^\/\///<Enter>
that removes a // at begin of line from the selected range when pressing CtrlU.
You can use the NERD commenter plugin for vim, which has support for a whole bunch of languages (I'm sure C++ is one of them). With this installed, to comment/uncomment any line, use <Leader>ci. To do the same for a block of text, select text by entering the visual mode and use the same command as above.
There are other features in this such as comment n lines by supplying a count before the command, yank before comment with <Leader>cy, comment to end of line with <Leader>c$, and many others, which you can read about in the link. I've found this plugin to be extremely useful and is one of my 'must have' plugins.
There's always #ifdef CHECK_THIS_LATER ... #endif which has the advantage of not causing problems with nested C-style comments (if you use them) and is easy to find and either uncomment or remove completely later.