    #if defined(CONDITION1) || defined(CONDITION2)

should work. :)

`#ifdef` is a bit less typing, but doesn&#39;t work well with more complex conditions

May use this-

    #if defined CONDITION1 || defined CONDITION2
    //your code here
    #endif

This also does the same-

    #if defined(CONDITION1) || defined(CONDITION2)
    //your code here
    #endif

---

**Further-**

- AND: `#if defined CONDITION1 &amp;&amp; defined CONDITION2`
- XOR: `#if defined CONDITION1 ^ defined CONDITION2`
- AND NOT: `#if defined CONDITION1 &amp;&amp; !defined CONDITION2`

I am really OCD about maintaining **strict column limits**, and not a fan of &quot;\&quot;
line continuation because you can&#39;t put a comment after it, so here is my method.

    //|&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;&#175;|//
    #ifdef  CONDITION_01             //|       |//
    #define             TEMP_MACRO   //|       |//
    #endif                           //|       |//
    #ifdef  CONDITION_02             //|       |//
    #define             TEMP_MACRO   //|       |//
    #endif                           //|       |//
    #ifdef  CONDITION_03             //|       |//
    #define             TEMP_MACRO   //|       |//
    #endif                           //|       |//
    #ifdef              TEMP_MACRO   //|       |//
    //|-  --  --  --  --  --  --  --  --  --  -|//
    
    printf(&quot;[IF_CONDITION:(1|2|3)]\n&quot;);
    
    //|-  --  --  --  --  --  --  --  --  --  -|//
    #endif                           //|       |//
    #undef              TEMP_MACRO   //|       |//
    //|________________________________________|//

Is Eclipse&#39;s Java compiler just a wrapper around the same core that the `javac` program is wrapped around, or is it a separate compiler altogether? If the latter, why would they reinvent the wheel?

What is the difference between javac and the Eclipse compiler?

I have one Application class to keep the global state of my application. But I&#39;m unable to register it in Manifest file? Any idea how to do this?

Register Application class in Manifest?

How can I add a &#39;or&#39; condition in #ifdef ?

I have tried:

```c
#ifdef CONDITION1 || CONDITION2
    
#endif
```

This does not work.


How to add a &#39;or&#39; condition in #ifdef

How can I add a 'or' condition in #ifdef ?
I have tried:
<pre><code class="hljs language-arduino">#ifdef CONDITION1 || CONDITION2
 
#endif
</code></pre>
This does not work.

When coding in either C or C++, where should I have the `#include`&#39;s?

callback.h:

    #ifndef _CALLBACK_H_
    #define _CALLBACK_H_
    
    #include &lt;sndfile.h&gt;
    #include &quot;main.h&quot;
    
    void on_button_apply_clicked(GtkButton* button, struct user_data_s* data);
    void on_button_cancel_clicked(GtkButton* button, struct user_data_s* data);
    
    #endif


callback.c:

    #include &lt;stdlib.h&gt;
    #include &lt;math.h&gt;
    
    #include &quot;config.h&quot;
    
    #include &quot;callback.h&quot;
    #include &quot;play.h&quot;
    
    void on_button_apply_clicked(GtkButton* button, struct user_data_s* data) {
      gint page;
      page = gtk_notebook_get_current_page(GTK_NOTEBOOK(data-&gt;notebook));
    
      ...


Should all includes be in either the .h or .c / .cpp, or both like I have done here?



#include in .h or .c / .cpp?

Is there any way to store an array of integers in one column of table? I want o/p like this:

    ident | value                                                            | count 
    ----------------+------------------------------------------------------------------------------------------------------------------------+-------
    563 | [0:10]={&quot;(0,0)&quot;,&quot;(1,100)&quot;,&quot;(2,200)&quot;,&quot;(3,300)&quot;,&quot;(4,400)&quot;,&quot;(5,500)&quot;} |    6

This I have already acheieved through postgres but i want same o/p from sqlite also.
Here column value store an array. I tried it through BLOB but it is not working. Somebody told me about serialized way but i am not sure how to do that.


How to store array in one column in Sqlite3?

I&#39;m getting a fairly long and confusing link error, and would love it if I could just paste it into some textbox on some website and have the names un-mangled for me.

Does anyone know of such a service?

Is there an online name demangler for C++?

I&#39;m using Eclipse with C++ code via linked resources on Linux. The code analysis index seems to be corrupted (Goto definition lands the cursor close to, but not on, the definition) Refreshing resources doesn&#39;t fix it, neither does restarting Eclipse.

Is there a way to flush the index and rebuild it?

Clean Eclipse Index, it is out of sync with code

This might be a stupid question, but I notice that in a good number of APIs, a lot of method signatures that take integer parameters that aren&#39;t intended to be modified look like:

`void method(int x);`

rather than:

`void method(const int &amp;x);`

To me, it looks like both of these would *function* exactly the same. (EDIT: apparently not in some cases, see answer by R Samuel Klatchko) In the former, the value is copied and thus can&#39;t change the original. In the latter, a constant reference is passed, so the original can&#39;t be changed.

What I want to know is why one over the other - is it because the performance is basically the same or even better with the former? e.g. passing a 16-bit value or 32-bit value rather than a 32-bit or 64-bit address? This was the only logical reason I could think of, I just want to know if this is correct, and if not, why and when one should prefer `int x` over `const int &amp;x` and vice versa.

Passing integers as constant references versus copying

I&#39;d like to know if my program is accessing NULL pointers or stale memory.

The backtrace looks like this:
&lt;pre&gt;
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x2b0fa4c8 (LWP 1333)]
0x299a6ad4 in pthread_mutex_lock () from /lib/libpthread.so.0
(gdb) bt
#0  0x299a6ad4 in pthread_mutex_lock () from /lib/libpthread.so.0
#1  0x0058e900 in ?? ()
&lt;/pre&gt;


How can I get GDB to tell me what address caused a segfault?

How can I create global variables that are shared in C? If I put it in a header file, then the linker complains that the variables are already defined. Is the only way to declare the variable in one of my C files and to manually put in `extern`s at the top of all the other C files that want to use it? That sounds not ideal.

shared global variables in C

I am looking for color space converter from RGB to HSV, specifically for the range 0 to 255 for both color spaces.

Algorithm to convert RGB to HSV and HSV to RGB in range 0-255 for both

I get an error on line 6 (initialize my_foo to foo_init) of the following program and I&#39;m not sure I understand why.

    typedef struct foo_t {
    	int a, b, c;
    } foo_t;
    
    const foo_t foo_init = { 1, 2, 3 };
    foo_t my_foo = foo_init;
    
    int main()
    {
    	return 0;
    }

Keep in mind this is a simplified version of a larger, multi-file project I&#39;m working on.  The goal was to have a single constant in the object file, that multiple files could use to initialize a state structure.  Since it&#39;s an embedded target with limited resources and the struct isn&#39;t that small, I don&#39;t want multiple copies of the source.  I&#39;d prefer not to use:

    #define foo_init { 1, 2, 3 }

I&#39;m also trying to write portable code, so I need a solution that&#39;s valid C89 or C99.

Does this have to do with the ORGs in an object file?  That initialized variables go into one ORG and are initialized by copying the contents of a second ORG?

Maybe I&#39;ll just need to change my tactic, and have an initializing function do all of the copies at startup.  Unless there are other ideas out there?

Error &quot;initializer element is not constant&quot; when trying to initialize variable with const

It seems I often spend way too much time trying to get a #define macro to do exactly what i want. I&#39;ll post my current dilemma below and any help is appreciated. But really the bigger question is whether there is any utility someone could recommend, to quickly display what a macro is actually doing? It seems like even the slow trial and error process would go much faster if I could see what is wrong.

Currently, I&#39;m dynamically loading a long list of functions from a DLL I made. The way I&#39;ve set things up, the function pointers have the same nanes as the exported functions, and the typedef(s) used to prototype them have the same names, but with a prepended underscore. So I want to use a define to simplify assignments of a long long list of function pointers.

For example, In the code statement below, &#39;hexdump&#39; is the name of a typedef&#39;d function point, and is also the name of the function, while _hexdump is the name of the typedef. If GetProcAddress() fails, a failure counter in incremented. 

    if (!(hexdump = (_hexdump)GetProcAddress(h, &quot;hexdump&quot;))) --iFail;
 
So let&#39;s say I&#39;d like to replace each line like the above with a macro, like this...

    GETADDR_FOR(hexdump )

Well this is the best I&#39;ve come up with so far. It doesn&#39;t work (my // comment is just to prevent text formatting in the message)...


    // #define GETADDR_FOR(a) if (!(a = (#_#a)GetProcAddress(h, &quot;/&quot;&quot;#a&quot;/&quot;&quot;))) --iFail; 


And again, while I&#39;d APPRECIATE an insight into what silly mistake I&#39;ve made, it would make my day to have a utility that would show me the error of my ways, by simply plugging in my macro.
 

Any utility to test expand C/C++ #define macros?

Is there some way to embed pragma statement in macro with other statements?

I am trying to achieve something like:

    #define DEFINE_DELETE_OBJECT(type)                      \
        void delete_ ## type_(int handle);                  \
        void delete_ ## type(int handle);                                                \
        #pragma weak delete_ ## type_ = delete_ ## type

I am okay with boost solutions (save for wave) if one exists.

Pragma in define macro

After discovering the [Boost preprocessor&#39;s capabilities][1] I found myself wondering: Is the C99 preprocessor Turing complete?

If not, what does it lack to not qualify?

[1]:http://www.boost.org/doc/libs/1_41_0/libs/preprocessor/doc/index.html


Is the C99 preprocessor Turing complete?

I know that I am trying to shoot myself in the leg ;) However, it will allow me to make the rest (big amount) of code smaller and more readable. 

Is there any tricky way to create preprocessor macro inside of another preprocessor macro?

Here is the example, what I am looking for. My real scenario is more complex

    // That&#39;s what I want to do and surely C++ doesn&#39;t like it.
    #define MACROCREATER(B) #define MACRO##B B+B
    
    void foo()
    {
     MACROCREATOR(5) // This should create new macro (#define MACRO5 5+5)
    
     int a = MACRO5; // this will use new macro
    }




Is there a way to do a #define inside of another #define?

I was wondering if someone could explain to me what the `#pragma pack` preprocessor statement does, and more importantly, why one would want to use it.

I checked out the [MSDN page][1], which offered some insight, but I was hoping to hear more from people with experience. I&#39;ve seen it in code before, though I can&#39;t seem to find where anymore.

  [1]: https://docs.microsoft.com/en-us/cpp/preprocessor/pack

Content Type	Original Author	Original Content on Stackoverflow
Question	michael	View Question on Stackoverflow
Solution 1 - C++	jalf	View Answer on Stackoverflow
Solution 2 - C++	Minhas Kamal	View Answer on Stackoverflow
Solution 3 - C++	KANJICODER	View Answer on Stackoverflow

How to add a 'or' condition in #ifdef

C++ Problem Overview

C++ Solutions

Solution 1 - C++

Solution 2 - C++

Solution 3 - C++

Register Application class in Manifest?

What is the difference between javac and the Eclipse compiler?

Attributions