What do I need to include to use DateTime? More specifically:
int month = System.DateTime.Now.Month;
Because I just put it there, and it doesn't recognize it.
Coding in C, with codeblocks
This is the error I am getting:
||=== Build: Debug in fm (compiler: GNU GCC Compiler) ===|
E:\CS50X\Projetos\FM\fm.c|224|error: 'System' undeclared (first use in this function)|
I just want to make a getage algorithm, but for that II need to get the current month and year.
Here is DateTime page:
http://msdn.microsoft.com/pt-br/library/system.datetime.aspx
The object you mention (System.DateTime.Now.Month) and the documentation to which you link (http://msdn.microsoft.com/pt-br/library/system.datetime.aspx) is all in the .NET Framework, used by languages such as C# and Visual Basic.
However, you're trying to compile C code:
|=== Build: Debug in fm (compiler: GNU GCC Compiler) ===|
Short answer... You can't use C# objects in C code. They're completely different languages on completely different platforms. If you're programming in C, you need to write your code in C. Different programming languages don't mix together like that.
drop system and use this
int month = DateTime.Now.Month;
Related
I've searched extensively for an answer but to no avail. I am progressing well with self-tutoring of the basics of PyQT5. I am using http://pyqt.sourceforge.net to gain insight into how classes and functions link together but I am finding the QT reference documentation http://doc.qt.io/qt-5/ a useful means of gaining further insight.
I can pick up on the fact that there is a standard notation running through the documentation but I cannot follow what various symbols and reoccurring text refers to. There also appear to be many parameters and nested parameters applied. I paste a few samples below:
void setFocus(Qt::FocusReason reason)
render(QPainter *painter, const QPoint &targetOffset = QPoint(), const QRegion &sourceRegion = QRegion(), RenderFlags renderFlags = RenderFlags( DrawWindowBackground | DrawChildren ))
qmake: QT += widgets
enum RenderFlag { DrawWindowBackground, DrawChildren, IgnoreMask }
My question: is the documentation following an industry standard notation when it uses symbols such as "|" ? If so, is there a reference I can refer to to interpret the notation? I've combed through the QT website but can find nothing.
Qt is a C++ library and the snippets you are showing are excerpts from C++ code.
except for the qmake line which is qmake code.
| is the bitwise OR operator. The enum RenderFlag consists of flags (where usually one unique bit is set) which can be combined via this operator.
I have legacy code for an embedded 8051 core (in a cypress FX2) that used to compile with other versions of SDCC. However, current SDCC doesn't know the _naked qualifier:
delay.c:27: syntax error: token -> '_naked' ; column 21
as triggered by
static void
udelay1 (void) _naked
{
_asm ; lcall that got us here took 4 bus cycles
ret ; 4 bus cycles
_endasm;
}
and other occurrences.
As _naked practically is supposed to tell the C compiler to "nah, ignore the fact that you're a C compiler and understand that you'd need to save frame context", I don't feel like I should just #define it away.
Is there any solution to this? Should I just go ahead and manually inline the assembler wherever a _naked function is used? I feel like I'd betraying the compiler on a CALL there, and that would change the timing.
_naked was replaced by __naked in newer versions of SDCC. Same applies to asm/__asm, at/__at, interrupt,bit,xdata/__….
So, this turned out to be an exercise in regex replacements.
I'm still having linker/ranlib/mostly ar problems, and CMake ignores what I instruct it to use as compilers, but oh well.
I want to use R's mathematical functions as provided in libRmath from Ocaml. I successfully installed the library via brew tap homebrew science && brew install --with-librmath-only r. I end up with a .dylib in /usr/local/lib and a .h in /usr/local/include. Following the Ocaml ctypes tutorial, i do this in utop
#require "ctypes.foreign";;
open Ctypes;;
open Foreign;;
let test_pow = foreign "pow_di" (float #-> int #-> returning float);;
this complains that it can't find the symbol. What am I doing wrong? Do I need to open the dynamic library first? Set some environment variables? After googling, I also did this:
nm -gU /usr/local/lib/libRmath.dylib
which gives a bunch of symbols all with a leading underscore including 00000000000013ff T _R_pow_di. In the header file, pow_di is defined via some #define directive from _R_pow_di. I did try variations of the name like "R_pow_di" etc.
Edit: I tried compiling a simple C program using Rmath using Xcode. After setting the include path manually to include /usr/local/include, Xcode can find the header file Rmath.h. However, inside the header file, there is an include of R_ext/Boolean.h which does not seem to exist. This error is flagged by Xcode and compilation stops.
Noob alert: this may be totally obvious to a C programmer...
In order to use external library you still need to link. There're at least two different ways, either link using compiler, or link even more dynamically using dlopen.
For the first method use the following command (as an initial approximation):
ocamlbuild -pkg ctypes.foreign -lflags -cclib,-lRmath yourapp.native
under premise that your code is put into yourapp.ml file.
The second method is to use ctypes interface to dlopen to open the library. Using the correct types and name for the C function call, this goes like this:
let library = Dl.dlopen ~filename:"libRmath.dylib" ~flags:[]
let test_pow = foreign ~from:library "R_pow_di" (double #-> int #-> returning double)
Ada is still new to me, so I am trying to find my way around the GPS IDE. I asked another question earlier, but I think this problem has precedence over that one, and may be at the root of my trouble.
When I compile, I am getting a long list of *warning: source file ... not found"
In my .gpr file, I have listed all of the spec and body source files and use the following naming scheme:
package Naming is
for Casing use "mixedcase";
for Dot_Replacement use ".";
for Spec_Suffix ("ada") use "_s.ada";
for Body_Suffix ("ada") use "_b.ada";
end Naming;
What is odd it the error messages all look either like this:
warning: source file "xxx_b.adb" not found
or this
warning: source file "xxx.adb" not found
Note that neither of these (xxxb.adb or xxx.adb) conform to the file specs, which should end with .ada.
Can someone explain what is going on here?
I'm 99% sure that the problem is one of the ones I mentioned in answer to your other question: GNAT does not normally support more than one compilation unit in a file. I got exactly the behaviour you describe with GPS and these files:
james_s.ada:
with Jane;
package James is
end James;
jim_s.ada:
package Jim is
end Jim;
package Jane is
end Jane;
The error message on compiling james_s.ada says it can't find Jane_s.ada, but when I ask GPS to go to the declaration of Jane it takes me to the "correct" line in jim_s.ada.
You could use gnatchop to split jim_s.ada, but it doesn't understand project files or naming conventions; you probably want to keep the existing names for the code that works, so you'd rename gnatchop's output as required.
However! to my great surprise, it turns out that GNAT does support having more than one compilation unit in a file, provided package Naming in the project file tells it about each unit in the file:
package Naming is
for Casing use "mixedcase";
for Dot_Replacement use ".";
for Spec_Suffix ("ada") use "_s.ada";
for Body_Suffix ("ada") use "_b.ada";
for Spec ("Jim") use "jim_s.ada" at 1;
for Spec ("Jane") use "jim_s.ada" at 2;
end Naming;
It's up to you whether to do this or to bite the bullet and use gnatchop, either on the multi-unit files or on the whole source tree.
First off, this isn't an Ada problem, its a Gnat problem. Other Ada compilers have no problem with the file names you are using.
However, Gnat is rather unique in that it expects there to be only one program unit (package body, package spec, stand-alone routine, etc) per source file. This is because it is also rather unique in that it expects to be able to find the source code for any program unit just by knowing that unit's Ada intentifier. Most other Ada compilers maintain some kind of library file that maps file names to program units, and you have to register all your files into it. (Whereas your typcial C compiler just leaves the problem of finding files for all your code up to the user entirely).
Generally the easiest thing to do with Gnat, the way that will cause you the least trouble, is to just use its default file naming convention (and of course don't put multiple program units in a single file.
If you already have some existing Ada code (perhaps developed for another compiler), the easiest way to import it into Gnat is typically to run the gnatchop tool on it all. So that's what I'd suggest you try.
From GPRbuild User's Guide:
Strings are used for values of attributes or as indexes for these attributes. They are in general case sensitive, except when noted otherwise [...]
Based on this, I believe you have to use "Ada" instead of "ada" as index for Spec_Suffix and Body_Suffix. I currently do not have access to the tools for testing this, so I suggest to just try it out.
I need to use the Sqlite vapi without any depedence on GLib. SQlite is non-gobject library, so it should be possible to do that.
However, when I try to compile the following file with the --profile posix
option,
using Sqlite;
void main() {
stdout.printf("Hello, World!");
}
I get am error messages:
sqlite3.vapi:357.56-357.59: error: The symbol `GLib' could not be found
public int bind_blob (int index, void* value, int n,
GLib.DestroyNotify destroy_notify);
^^^^
sqlite3.vapi:362.68-362.71: error: The symbol `GLib' could not be found
public int bind_text (int index, owned string value, int n = -1,
GLib.DestroyNotify destroy_notify = GLib.g_free);
^^^^
sqlite3.vapi:411.42-411.45: error: The symbol `GLib' could not be found
public void result_blob (uint8[] data, GLib.DestroyNotify?
destroy_notify = GLib.g_free);
^^^^
sqlite3.vapi:420.59-420.62: error: The symbol `GLib' could not be found
public void result_text (string value, int length = -1,
GLib.DestroyNotify? destroy_notify = GLib.g_free);
^^^^
Compilation failed: 4 error(s), 0 warning(s)
It seems that several of the functions defined in the sqlite vapi make references to the GLib.g_free and GLib.DestroyNotify symbols. Are there any posix alternatives to those?
That should be fairly simple to solve, and I can imagine several solutions.
It boils down to declaring a different delegate void DestroyNotify (void* data) (either in the posix.vapi or sqlite3.vapi) and bind free() in posix.vapi.
The problem is the namespace, and you might need to file a bug and discuss it with the developers. If you want to avoid this problem and are ready to go with a workaround, just create a mini glib.vapi GLib namespace, where you bind only the DestroyNotify() and g_free() (binding to libc/posix free).
I would think that sqlite3 should not use GLib, but rather libc/posix, so you should be fine by modifying only posix.vapi and sqlite3.vapi and filing a bug with your patch (awesome, a contrib!).
Note that classes are unavailable under the POSIX profile, as Vala requires a support library (i.e. GLib, Dova) to support those features. Jürg Billeter has acknowledged that support for the POSIX profile is experimental and limited:
https://bugzilla.gnome.org/show_bug.cgi?id=618348
The only way you have is re-writing the sqlite VAPI (or just the classes/methods you need) making them posix friendly (but I guess you can't use classes in that way).
if the vapi for sqlite depends on glib you could just write your own or use the sqlite c code with c and just make some extern statements for the functions you need. for example i made a tool wich mixes vala and c for linux pure c for win32 and objective c and c for mac
https://github.com/boscowitch/wadoku-notify
i just added the 2 functions i need at the beginning of my vala app like this:
extern void init_db(char * path,bool mm);
extern void lookup(char * str);
i added the whole sqlite source cause i needed to activate full text indexing and change a bit in the code and in the beginning of vala there was no sqlite vapi