For **Mac OS**:

    #ifdef __APPLE__

For **MingW** on Windows:

    #ifdef __MINGW32__

For **Linux**:

    #ifdef __linux__

For other Windows compilers, check [this thread][1] and [this][2] for several other compilers and architectures.


  [1]: https://stackoverflow.com/questions/430424/how-can-i-detect-the-operating-system-in-c-c
  [2]: https://stackoverflow.com/questions/152016/detecting-cpu-architecture-compile-time/152067#152067

See: http://predef.sourceforge.net/index.php

This project provides a reasonably comprehensive listing of pre-defined `#defines` for many operating systems, compilers, language and platform standards, and standard libraries.

Here&#39;s what I use:

    #ifdef _WIN32 // note the underscore: without it, it&#39;s not msdn official!
        // Windows (x64 and x86)
    #elif __unix__ // all unices, not all compilers
        // Unix
    #elif __linux__
        // linux
    #elif __APPLE__
        // Mac OS, not sure if this is covered by __posix__ and/or __unix__ though...
    #endif

**EDIT:** Although the above might work for the basics, remember to verify what macro you want to check for by looking at the [Boost.Predef reference pages][1]. Or just use Boost.Predef directly.


  [1]: http://www.boost.org/doc/libs/release/libs/predef/doc/html/predef/reference.html

If you&#39;re writing C++, I can&#39;t recommend using the [Boost](http://www.boost.org/) libraries strongly enough.

The latest version (1.55) includes a new [Predef](http://www.boost.org/doc/libs/1_55_0/libs/predef/doc/html/index.html) library which covers [exactly what you&#39;re looking for](http://www.boost.org/doc/libs/1_55_0/libs/predef/doc/html/predef/reference/boost_os_operating_system_macros.html), along with dozens of other platform and architecture recognition macros.


    #include &lt;boost/predef.h&gt;
    
    // ...
    
    #if BOOST_OS_WINDOWS
    
    #elif BOOST_OS_LINUX
    
    #elif BOOST_OS_MACOS
    
    #endif


I have the below message (slightly changed):

&gt; &quot;Enter the competition by January 30, 2011 and you could win up to
&gt; $$$$ — including amazing summer trips!&quot;

I currently have:

    &lt;p style=&quot;font-size:14px; color:#538b01; font-weight:bold; font-style:italic;&quot;&gt;

formatting the text string, but want to change the color of &quot;January 30, 2011&quot; to #FF0000 and &quot;summer&quot; to #0000A0. 

How do I do this strictly with HTML or inline CSS?

HTML: Changing colors of specific words in a string of text

In [my previous question I got an excellent answer](https://stackoverflow.com/questions/4087919/how-can-i-improve-my-paw-detection/4092160#4092160) that helped me detect where a paw hit a pressure plate, but now I&#39;m struggling to link these results to their corresponding paws:

![alt text][1]

I manually annotated the paws (RF=right front, RH= right hind, LF=left front, LH=left hind).

As you can see there&#39;s clearly a repeating pattern and it comes back in almost every measurement. [Here&#39;s a link to a presentation of 6 trials that were manually annotated.](https://docs.google.com/viewer?a=v&amp;pid=explorer&amp;chrome=true&amp;srcid=0B1W3cjBV_DpNYjNhYjFjYzctZjJjNi00ODVkLWExMjctYmQ5YWJhOWU3ZDg0&amp;hl=en&amp;authkey=CO6_lbIE)

My initial thought was to use heuristics to do the sorting, like:

- There&#39;s a ~60-40% ratio in weight bearing between the front and hind paws;
- The hind paws are generally smaller in surface;
- The paws are (often) spatially divided in left and right.

However, I’m a bit skeptical about my heuristics, as they would fail on me as soon as I encounter a variation I hadn’t thought off. They also won’t be able to cope with measurements from lame dogs, whom probably have rules of their own. 

Furthermore, the annotation suggested by Joe sometimes get&#39;s messed up and doesn&#39;t take into account what the paw actually looks like.

Based on the answers I received [on my question about peak detection within the paw](https://stackoverflow.com/questions/3684484), I’m hoping there are more advanced solutions to sort the paws. Especially because the pressure distribution and the progression thereof are different for each separate paw, almost like a fingerprint. I hope there&#39;s a method that can use this to cluster my paws, rather than just sorting them in order of occurrence. 

![alt text][2]

**So I&#39;m looking for a better way to sort the results with their corresponding paw.** 

For anyone up to the challenge, [I have pickled a dictionary](https://stackoverflow.com/questions/3685265/how-to-write-a-multidimensional-array-to-a-text-file/3685295#3685295) with [all the sliced arrays that contain the pressure data of each paw](http://dl.dropbox.com/u/5207386/walk_sliced_data) (bundled by measurement) and [the slice that describes their location](http://dl.dropbox.com/u/5207386/walk_data_slices) (location on the plate and in time). 

To clarfiy: walk_sliced_data is a dictionary that contains [&#39;ser_3&#39;, &#39;ser_2&#39;, &#39;sel_1&#39;, &#39;sel_2&#39;, &#39;ser_1&#39;, &#39;sel_3&#39;], which are the names of the measurements. Each measurement contains another dictionary, [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10] (example from &#39;sel_1&#39;) which represent the impacts that were extracted. 

Also note that &#39;false&#39; impacts, such as where the paw is partially measured (in space or time) can be ignored. They are only useful because they can help recognizing a pattern, but 
won&#39;t be analyzed. 

And for anyone interested, [I’m keeping a blog with all the updates regarding the project!](http://www.flipserd.com/blog)

  [1]: http://i.stack.imgur.com/1KbIz.png
  [2]: http://i.stack.imgur.com/hFmOn.png

How to sort my paws?

I&#39;m writing a cross-platform code, which should compile at linux, windows, Mac OS. On windows, I must support visual studio and mingw.

There are some pieces of platform-specific code, which I should place in `#ifdef .. #endif` environment. For example, here I placed win32 specific code:

    #ifdef WIN32
    #include &lt;windows.h&gt;
    #endif

But how do I recognize linux and mac OS? What are defines names (or etc.) I should use?


How to identify platform/compiler from preprocessor macros?

I'm writing a cross-platform code, which should compile at linux, windows, Mac OS. On windows, I must support visual studio and mingw.
There are some pieces of platform-specific code, which I should place in <code>#ifdef .. #endif</code> environment. For example, here I placed win32 specific code:
<pre><code class="hljs language-arduino">#ifdef WIN32
#include &#x3C;windows.h>
#endif
</code></pre>
But how do I recognize linux and mac OS? What are defines names (or etc.) I should use?

I know that the use of QML is quite new in Qt and I was wondering if I should design my application using Qt Designer or QML. I will be using a MVC pattern and my main concern if I use QML for the GUI is that it might not be easy to integrate inside the rest of my C++ app.

*Feel free to give your personal advice, I would greatly appreciate it.
Thank you!*

Qt Designer C++ or QML for GUI

Could someone tell what is the correct way to work with a vector of arrays? 

I declared a vector of arrays (`vector&lt;float[4]&gt;`) but got `error: conversion from &#39;int&#39; to non-scalar type &#39;float [4]&#39; requested` when trying to `resize` it. What is going wrong?



Correct way to work with vector of arrays

I had declared a Boolean variable `bool abc;` in a class and thought that it would be false by default. An *if* condition in my program, `if (abc)`, turned out to be true, so I output the value of abc, and saw that it contained the value 55. Is this normal?

Do we always have to assign &#39;bool abc=false&#39; to be sure that it is false?






Aren&#39;t Boolean variables always false by default?

I read that an overloaded operator declared as member function is *asymmetric* because it can have only one parameter and the other parameter passed automatically is the `this` pointer. So no standard exists to compare them. On the other hand, overloaded operator declared as a `friend` is *symmetric* because we pass two arguments of the same type and hence, they can be compared.

My question is that when i can still compare a pointer&#39;s lvalue to a reference, why are friends preferred? (using an asymmetric version gives the same results as symmetric)
Why do STL algorithms use only symmetric versions?



Operator overloading : member function vs. non-member function?

Interview question: Which one will execute faster, `if (flag==0)` or `if (0==flag)`? Why?


Which one will execute faster, if (flag==0) or if (0==flag)?

I have recorded a macro that I want to share with my work colleague.

In what location are these recorded macros saved, so that I can add it to his machine?

If interested, the macro is for taking a list of values and adding quotes and comma so that it can be used in the `WHERE` clause of of an SQL query (`WHERE x IN (&#39;value1&#39;,&#39;value2&#39;,&#39;value3&#39;)`).

Where are the recorded macros stored in Notepad++?

In my program I&#39;m reading integers form console many times. Every time, I need to type this line.

    new Scanner(System.in).nextInt(); 

I&#39;m used to C/C++ and I&#39;m wondering if I can define something like

    #define READINT Scanner(System.in).nextInt(); 

and then, in every place in my java program I can read form console as 

    int a = new READINT;


But I read form books Java does not support macros. 

Someone please explain me why is it so, and can I do this in  any other way.

Can I have macros in Java source files

I just learned of [X-Macros][1]. What real-world uses of X-Macros have you seen? When are they the right tool for the job?


  [1]: http://en.wikibooks.org/wiki/C_Programming/Preprocessor#X-Macros

Real-world use of X-Macros

I am exploring Qt source code and came across this `Q_D` macro. Could some one please explain what it does? 

Almost all the time it should return a widget of the type given as a parameter which is the `d` variable. Need more clarification on this.


What does Q_D macro do in Qt

The standard predefined macro `__FILE__` available in C shows the full path to the file. Is there any way to short the path? I mean instead of

    /full/path/to/file.c

I see

    to/file.c

or 

    file.c

__FILE__ macro shows full path

A file named `stdafx.h` is automatically generated when I start a project in Visual Studio 2010. I need to make a cross-platform C++ library, so I don&#39;t/can&#39;t use this header file.

What is `stdafx.h` used for? Is it OK that I just remove this header file?

What is &quot;stdafx.h&quot; used for in Visual Studio?

There are tools for developing [cross-platform browser plugins][1].

Are there any similar tools or APIs for browser extensions (i.e. toolbars, or filter systems like AdBlock)?


  [1]: http://www.firebreath.org

Cross-Browser Extensions API?

If there&#39;s some cross-platform C/C++ code that should be compiled on Mac OS X, iOS, Linux, Windows, how can I detect them reliably during preprocessor process?

How to detect reliably Mac OS X, iOS, Linux, Windows in C preprocessor?

How can I use a file inside my app folder in Python?  Platform independent of course...
something similar to this:

    #!/bin/sh
    mypath=${0%/*}
    LIBDIR=$mypath/modules

Platform-independent file paths?

Any portable code that uses bitfields seems to distinguish between little- and big-endian platforms. See the [declaration of struct iphdr in linux kernel](http://lxr.linux.no/#linux+v2.6.38/include/linux/ip.h) for an example of such code. I fail to understand why bit endianness is an issue at all.

As far as I understand, bitfields are purely compiler constructs, used to facilitate bit level manipulations.

For instance, consider the following bitfield:
&lt;code&gt;&lt;pre&gt;
struct ParsedInt {
    unsigned int f1:1;
    unsigned int f2:3;
    unsigned int f3:4;
};
uint8_t i;
struct ParsedInt *d = &amp;i;
&lt;/pre&gt;&lt;/code&gt;
Here, writing &lt;code&gt;d-&gt;f2&lt;/code&gt; is simply a compact and readable way of saying &lt;code&gt;(i&gt;&gt;1) &amp;  (1&lt;&lt;4 - 1)&lt;/code&gt;.

However, bit operations are well-defined and work regardless of the architecture. So, how come bitfields are not portable?

Why bit endianness is an issue in bitfields?

I&#39;m using an open source library which seems to have lots of preprocessing directives to support many languages other than C. So that I can study what the library is doing I&#39;d like to see the C code that I&#39;m compiling after preprocessing, more like what I&#39;d write.

Can gcc (or any other tool commonly available in Linux) read this library but output C code that has the preprocessing converted to whatever and is also readable by a human?

Can gcc output C code after preprocessing?

My preprocessor appears to assume that undefined constants are 0 for the purpose of evaluating `#if` conditions.

Can this be relied upon, or do undefined constants give undefined behaviour?

What is the value of an undefined constant used in #if?

Consider this code:

    #define F(x, ...) X = x and VA_ARGS = __VA_ARGS__
    #define G(...) F(__VA_ARGS__)
    F(1, 2, 3)
    G(1, 2, 3)

The expected output is `X = 1 and VA_ARGS = 2, 3` for both macros, and that&#39;s what I&#39;m getting with GCC, however, MSVC expands this as:

    X = 1 and VA_ARGS = 2, 3
    X = 1, 2, 3 and VA_ARGS =

That is, `__VA_ARGS__` is expanded as a single argument, instead of being broken down to multiple ones.

Any way around this?

MSVC doesn&#39;t expand __VA_ARGS__ correctly

Is there a way to globally declare a #define?

Like I want to have a file that has for instance,

    #define MONO

and I want all source-code files to know that this pre-processor directive is defined. How would I achieve that?

Solution-wide #define

I&#39;m writing a multiview app that utilizes a class called `RootViewController` to switch between views.

In my `MyAppDelegate` header, I create an instance of the `RootViewController` called `rootViewController`. I&#39;ve seen examples of such where the @class directive is used as a &quot;forward class declaration,&quot; but I&#39;m not quite sure what this means or accomplishes.

    #import &lt;UIKit/UIKit.h&gt;
    @class RootViewController;
    @interface MyAppDelegate
    .
    .
    .

Content Type	Original Author	Original Content on Stackoverflow
Question	Arenim	View Question on Stackoverflow
Solution 1 - C++	karlphillip	View Answer on Stackoverflow
Solution 2 - C++	John Bartholomew	View Answer on Stackoverflow
Solution 3 - C++	rubenvb	View Answer on Stackoverflow
Solution 4 - C++	rvalue	View Answer on Stackoverflow

How to identify platform/compiler from preprocessor macros?

C++ Problem Overview

C++ Solutions

Solution 1 - C++

Solution 2 - C++

Solution 3 - C++

Solution 4 - C++

How to sort my paws?

HTML: Changing colors of specific words in a string of text

Attributions