I need to define a variable name for different files inside a Fortran code, while I 'm using this commands
open(unit=5,file="plot.sm")
write(unit=zbin_str,fmt='(f5.2)') zbin
plotname="LF_z"//zbin_str//".ps"
write(5,"dev postencap" plotname)
write(5,"toplabel LF for",//zbin_str//)
I'm receiving these errors :
Syntax error, found '//' when expecting one of: ( * <IDENTIFIER> <CHAR_CON_KIND_PARAM> <CHAR_NAM_KIND_PARAM> <CHARACTER_CONSTANT> ...
write(5,"toplabel LF for",//zbin_str//)
error #6355: This binary operation is invalid for this data type. [PLOTNAME]
write(5,"dev postencap" plotname)
An arithmetic or LOGICAL type is required in this context.
write(5,"dev postencap" plotname)
How I can define the available name inside the Fortran code??
Thanks
Neither of these lines
write(5,"dev postencap" plotname)
write(5,"toplabel LF for",//zbin_str//)
is well-formed; that's what the compiler is trying to tell you.
Beyond that, I'm not sure what you are trying to do or, therefore, how to fix it. Unless you use keywords your Fortran compiler will understand the 2nd argument in a write statement to be the format specifier in which you want to present the output. I can't see how either "dev postencap" plotname or "toplabel LF for",//zbin_str// can be made into a valid format specifier. Perhaps what you want is
write(5,'(a32)') "dev postencap"//plotname
write(5,'(a32)') "toplabel LF for"//zbin_str
Anything more would be based on guesswork. If this doesn't answer your question explain it more clearly if you can.
Related
I have searched around quite a bit and have failed to find an answer. In AutoHotKey, I am not sure the difference when a single percent is used near the beginning of a line, and when a variable is enclosed between two percent signs. I usually use trial and error to find when I use one or the other, I am hoping someone could shed some light on what the difference is or explain what it is actually doing.
Here are some examples of this in action.
Example 1: I noticed if you have multiple variables along with text, scripts tend to go with the preceding percent. Such as:
some_val := Clipboard
loop 5
msgbox % "Index:" . A_Index . ", variable:" . some_val
Example 2: I often see this as well, and sometimes it appears it must be used. Is this true?
some_variable := "test text to send"
Send, %some_variable%
Wrapping in double percent signs is legacy AHK and basically there is no need to ever use it anymore. Only reason to wrap in double % would be being stuck behind in the old times, or maybe one could argue it also being more convenient, or something, to write in some cases, but I'm not buying it.
The legacy syntax is replaced by expression syntax.
The expression syntax is closer to how many other languages behave. AHK legacy syntax really is a mess.
All legacy commands (MsgBox for example) use the old legacy syntax on each parameter (unless otherwise specified).
If you specify a % followed up by a space at the start of the parameter, you're forcing AHK to evaluate an expression on that parameter instead of reading it as a legacy text parameter.
Example:
MsgBox, 5+5
We're using a legacy command, we're not starting the parameter off with a % and a space, so we're using the legacy syntax. The MsgBox is going to print the literal text 5+5 instead of 10.
MsgBox, % 5+5
Again, legacy command, but now we're forcing AHK to evaluate an expression here, 5+5.
The result of expression's evaluation is going to be passed onto the MsgBox command and the MsgBox is going to print 10.
If we wanted to MsgBox to print the literal text 5+5, and use the expression syntax to do it, we'd do MsgBox, % "5+5".
Quotation marks in expression syntax mean we're specifying a string.
Well then there's the problem of knowing when you're in expression syntax, and when you're in the legacy syntax.
By default, you're basically always in an expression.
You leave it by for example using a command or = to assign.
If the difference between a command and a function isn't clear to you, here's an example:
Command, % 7+3, % MyCoolArray[4], % SomeOtherNiceFunction(), % false
Function(7+3, MyCoolArray[4], SomeOtherNiceFunction(), false)
In the command we specified a % followed up by a space to evaluate the expressions on each parameter, and in the function, we didn't have to do that since we're already in an expression.
And if you're not clear on the difference between = and :=,
= is legacy and deprecated, it assigns plain text to a variable
:= assigns the result of an expression to a variable.
So that's what I could write from on top of my head.
If you had some more complex examples, I could try showing on them. Maybe convert some code you may have over to expression syntax, make it 100% free of legacy syntax.
And here's a good page on the documentation you should give a read:
https://www.autohotkey.com/docs/Language.htm
I am trying to understand the perl commands below:
$my = << EOU;
This is an example.
Example too.
EOU
What is the name of this way? Could somebody can explain more about this "multi-line writing" command?
Essentially the syntax is allowing you to put anything unique as a marker so that it won't conflict with your contents. You can do this:
$my = <<ABCDEFG;
This is an example.
Example too.
BLAH
ABCDEFG
Everything between "This.." and "BLAH" will be assigned to the variable. Note that you shouldn't have a space after the << symbols otherwise you will get a syntax error. It helps avoid adding CR characters, or append (.) everywhere, and useful when passing data into another application (eg. ftp session). Here Documents is the correct term for this.
Everything between <<EOU and EOU is a multi-line, non-escapable, string. It's nothing fancy, think of them as start and end quote marks with nothing inside requiring escapes to be literally what you typed...
In the Fortran program, is it possible to read an expression including the variables ?
For example, the input file is （if necessary, we can change the input form of the expression,e.g.,the binary form）,
2(a-4b)
It should be noted that the input expression has a very simple form and it only contains integer or fraction or some variables,like the following in the list,
{0,232,-2/5a,3a-b,b/9}
Here 2a means 2*a
The Fortran program is
Program test
implicit none
real(kind=8)::a,b,exp
a=10.
b=3.
! open file and read the input expression
! that is, exp=2*(a-4*b)
write(*,*) exp ! we can get exp=-4.0
end program
For the complicated expressions, it is obviously not a good idea for Fortran. I just want to know, in this simple input expression case, is it possible to find a better way ?
A site with tests of three expression evaluators in Fortran is http://www.angelfire.com/ab5/extensao/report.htm . Only the link to the "Brazilian" one works.
There is also a Sourceforge project fparser http://fparser.sourceforge.net/ .
Fortran cannot do this unless you write code that can parse the arbitrary expression, substitute and solve, which is a bit of work (see the comment below for details). Fortran is compiled and there is no way to load source on the fly, compile and run it, which is essentially what you are asking. You might look into a language such as Lisp where doing this is should be somewhat trivial. Likewise any scripted language will have facilities to evaluate code, which can do what you are asking.
I apologize if this is a newb question, but I have read the documentation here and it says nothing about having to input any command before using substring.
However, when I try to call it as follows:
substring('hello world', 2)
It gives me the error
??? Undefined function or method 'substring' for input arguments of type 'char'.
What is the correct way to invoke this substring?
Not to detract from the OP's answer, which actually more directly adresses the question you ask, but assuming all you want to do is extract a certain number of characters from a string, MATLAB's indexing is all you need:
myString = 'Hello, world!';
mySubstring = myString(3:end)
mySubstring =
llo, world!
substring is not a MATLAB function at all, at least in MATLAB proper. There IS a substring JAVA function, but I have no idea if that is what you are asking.
>> which substring
substring is a Java method % java.lang.String method
The above also tells you what you will need to do. Look here. (Google is your friend. Of course, you could as easily have done exactly what I just did, and gotten this answer far more quickly.)
You may also be talking about some custom code, written by some colleague of yours. In that case, talk to your friend. Very often I hear about tools that were written by someone, then left around as legacy code, unsupported. Eventually, it just disappears due to path issues when new versions of MATLAB are installed.
You might actually want strsplit. This will parse char data by a given or default delimiter and return a cell array of the pieces.
This is C macro weirdness question.
Is it possible to write a macro that takes string constant X ("...") as argument and evaluates to sting Y of same length such that each character of Y is [constant] arithmetic expression of corresponding character of X.
This is not possible, right ?
No, the C preprocessor considers string literals to be a single token and therefore it cannot perform any such manipulation.
What you are asking for should be done in actual C code. If you are worried about runtime performance and wish to delegate this fixed task at compile time, modern optimising compilers should successfully deal with code like this - they can unroll any loops and pre-compute any fixed expressions, while taking code size and CPU cache use patterns into account, which the preprocessor has no idea about.
On the other hand, you may want your code to include such a modified string literal, but do not want or need the original - e.g. you want to have obfuscated text that your program will decode and you do not want to have the original strings in your executable. In that case, you can use some build-system scripting to do that by, for example, using another C program to produce the modified strings and defining them as macros in the C compiler command line for your actual program.
As already said by others, the preprocessor sees entire strings as tokens. There is only one exception the _Pragma operator, that takes a string as argument and tokenizes its contents to pass it to a #pragma directive.
So unless your targeting a _Pragma the only way to do things in the preprocessing phases is to have them written as token sequences, manipulate them and to stringify them at the end.