To specify a directory to search for (binary) libraries, you just use `-L`:

    -L/data[...]/lib

To specify the actual library name, you use `-l`:

    -lfoo  # (links libfoo.a or libfoo.so)

To specify a directory to search for *include* files (different from libraries!) you use `-I`:

    -I/data[...]/lib

So I think what you want is something like

    g++ -g -Wall -I/data[...]/lib testing.cpp fileparameters.cpp main.cpp -o test

These compiler flags (amongst others) can also be found at the GNU GCC Command Options manual:

 - [3.16 Options for Directory Search](https://gcc.gnu.org/onlinedocs/gcc/Directory-Options.html)




In your MakeFile or CMakeLists.txt you can set CMAKE_CXX_FLAGS as below:

    set(CMAKE_CXX_FLAGS &quot;${CMAKE_CXX_FLAGS} -I/path/to/your/folder&quot;)

Alternatively you could setup environment variables.
Suppose you are using `bash`, then in `~/.bashrc`, write

```bash
C_INCLUDE_PATH=&quot;/data/.../lib/:$C_INCLUDE_PATH&quot; ## for C compiler
CPLUS_INCLUDE_PATH=&quot;/data/.../lib/:$CPLUS_INCLUDE_PATH&quot; ## for Cpp compiler
export C_INCLUDE_PATH
export CPLUS_INCLUDE_PATH
```

and source it with `source ~/.bashrc`.
You should be good to go.

I would like to be able to do something like this:

    class ThingIDs
    {
        const Something = 1;
        const AnotherThing = 2;
    }

    $thing = &#39;Something&#39;;
    $id = ThingIDs::$thing;

This doesn&#39;t work. Is there a straightforward way of doing something equivalent? Note that I&#39;m stuck with the class; it&#39;s in a library I can&#39;t rewrite. I&#39;m writing code that takes arguments on the command line, and I would *really* like it to take symbolic names instead of id numbers.

Get value of dynamically chosen class constant in PHP

how to check the text of `edittext` is email address or not without using `javascript` and regular expression?
Here I used `inputtype=&quot;textEmailAddress&quot;` this is working but no error message is display.

How to check edittext&#39;s text is email address or not?

I am trying to include the path to extra libraries in my makefile, but I can&#39;t figure out how to get the compiler to use that path.  so far I have:

    g++ -g -Wall testing.cpp fileparameters.cpp main.cpp -o test

and I want to include the path to

    /data[...]/lib

because testing.cpp includes files from that library.  Also, I&#39;m on a linux machine.

EDIT: Not a path to a library.  Just to files that were included.  My bad.

How do I include a path to libraries in g++

I am trying to include the path to extra libraries in my makefile, but I can't figure out how to get the compiler to use that path. so far I have:
<pre><code class="hljs language-bash">g++ -g -Wall testing.cpp fileparameters.cpp main.cpp -o test
</code></pre>
and I want to include the path to
<pre><code class="hljs language-bash">/data[...]/lib
</code></pre>
because testing.cpp includes files from that library. Also, I'm on a linux machine.
EDIT: Not a path to a library. Just to files that were included. My bad.

Is there a way to convert this:

    /C:/Users/David/Dropbox/My%20Programs/Java/Test/bin/myJar.jar
into this?:

    C:\Users\David\Dropbox\My Programs\Java\Test\bin\myJar.jar

I am using the following code, which will return the full path of the .JAR archive, or the /bin directory.

    fullPath = new String(MainInterface.class.getProtectionDomain()
    			.getCodeSource().getLocation().getPath());

The problem is, `getLocation()` returns a `URL` and I need a normal windows filename.
I have tried adding the following after `getLocation()`:

`toString()` and `toExternalForm()` both return:
	
    file:/C:/Users/David/Dropbox/My%20Programs/Java/Test/bin/

`getPath()` returns:
	
    /C:/Users/David/Dropbox/My%20Programs/Java/Test/bin/

Note the `%20` which should be converted to space.
  
Is there a quick and easy way of doing this? 

Convert URL to normal windows filename Java

When I run Ruby commands like `gem -v` I get this error:

&gt; /Users/kristoffer/.rvm/rubies/ruby-1.9.2-p180/bin/gem:4:
&gt; warning: Insecure world writable dir
&gt; /Users/kristoffer in PATH, mode 040777 

&gt;1.6.2

First of all I don&#39;t understand what this means. /Users/kristoffer is not in my path according to `echo $PATH`. The result of `echo $PATH` is:

&gt; /Users/kristoffer/.rvm/gems/ruby-1.9.2-p180/bin:/Users/kristoffer/.rvm/gems/ruby-1.9.2-p180@global/bin:/Users/kristoffer/.rvm/rubies/ruby-1.9.2-p180/bin:/Users/kristoffer/.rvm/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin

As you can see, the PATH is pretty clean. Just the default path + what RVM added. 

I&#39;ve seen the other posts similar to this where the recommended way to solve the issue is to run `chmod go-w path/to/folder`

However, I&#39;m pretty sure that it&#39;s a bad idea to make my Home folder non-writeable, right? I&#39;ve repaired permissions using Disk Utility and it didn&#39;t find anything wrong with the permissions on my Home folder.

Any idea of what the problem is and how I can fix it?

Insecure world writable dir /Users/username in PATH, mode 040777 when running Ruby commands

I am just wondering: I am looking for a way to validate if a given path is valid.
*(Note: I do not want to check if a file is existing! I only want to proof the validity of the path - So if a file could possibly exists at the location)*.

Problem is, I can&#39;t find anything in the .Net API.
Due to the many formats and locations that Windows supports, I&#39;d rather use something MS-native.

Since the function should be able to check against:

&gt; - Relative Paths (./)
&gt; - Absolute Paths (c:\tmp)
&gt; - UNC-Pathes (\\some-pc\c$)
&gt; - NTFS-Limitations like the full path 1024 chars - If I am not mistaken exceeding the path will make a file inaccessible for many
&gt; internal Windows functions. Renaming it with Explorer still works
&gt; - Volume GUID Paths : &quot;\\?\Volume{GUID}\somefile.foo

Does anyone have a function like this?


Check whether a path is valid

I&#39;ve been trying to add the Python path to the command line on Windows, yet no matter the method I try, nothing seems to work. I&#39;ve used the `set` command, I&#39;ve tried adding it through the Edit Environment Variables prompt, etc.

Furthermore, if I run the set command on the command line it lists this.

    python = c:\python27

Yet it still doesn&#39;t recognize the Python command.

Reading the documentation, and various other sources haven&#39;t seemed to help.

Just to clarify further, I&#39;ve appended the path of the Python executable to PATH in the Edit Environment prompt. Doesn&#39;t seem to work.

Adding Python to PATH on Windows

ASP.NET offers two ways to specify paths for style sheets:

```
&lt;link href=&quot;/common/black_theme/css/style.css&quot; rel=&quot;stylesheet&quot;&gt;   (this is working)
&lt;link href=&quot;~/common/black_theme/css/style.css&quot; rel=&quot;stylesheet&quot;&gt;  (this is not working)
```

- How are these paths resolved?
- Why are the generated paths different?
- Which one should I pick in which case?

As per my knowledge, `~` represents the root directory of the application.
&quot;common&quot; is the folder below the website root (named `testsite.demo`) in IIS.

Physical path: `D:\Physicalpath\WarpFirstSite\testsite.demo`&lt;br&gt;
&quot;common&quot; folder: `D:\Physicalpath\WarpFirstSite\testsite.demo\common`





Slash (/) vs tilde slash (~/) in style sheet path

Developing environment: GNU GCC (g++) 4.1.2

While I&#39;m trying to investigate how to increase &#39;code coverage - particularly function coverage&#39; in unit testing, I&#39;ve found that some of class dtor seems to be generated multiple times. Does some of you have any idea on why, please?

I tried and observed what I mentioned the above by using the following code.

In &quot;test.h&quot;

    class BaseClass
    {
    public:
    	~BaseClass();
    	void someMethod();
    };
    
    class DerivedClass : public BaseClass
    {
    public:
    	virtual ~DerivedClass();
    	virtual void someMethod();
    };

In &quot;test.cpp&quot;

    #include &lt;iostream&gt;
    #include &quot;test.h&quot;
    
    BaseClass::~BaseClass()
    {
    	std::cout &lt;&lt; &quot;BaseClass dtor invoked&quot; &lt;&lt; std::endl;
    }
    
    void BaseClass::someMethod()
    {
    	std::cout &lt;&lt; &quot;Base class method&quot; &lt;&lt; std::endl;
    }
    
    DerivedClass::~DerivedClass()
    {
    	std::cout &lt;&lt; &quot;DerivedClass dtor invoked&quot; &lt;&lt; std::endl;
    }

    void DerivedClass::someMethod()
    {
    	std::cout &lt;&lt; &quot;Derived class method&quot; &lt;&lt; std::endl;
    }
    
    int main()
    {
    	BaseClass* b_ptr = new BaseClass;
    	b_ptr-&gt;someMethod();
    	delete b_ptr;
    }

When I built the above code (g++ test.cpp -o test) and then see what kind of symbols have been generated as follows,

nm --demangle test

I could see the following output.

    ==== following is partial output ====
    08048816 T DerivedClass::someMethod()
    08048922 T DerivedClass::~DerivedClass()
    080489aa T DerivedClass::~DerivedClass()
    08048a32 T DerivedClass::~DerivedClass()
    08048842 T BaseClass::someMethod()
    0804886e T BaseClass::~BaseClass()
    080488f6 T BaseClass::~BaseClass()

My questions are as follows.

1) Why multiple dtors have been generated (BaseClass - 2, DerivedClass - 3)?

2) What are the difference among these dtors? How those multiple dtors will be selectively used?

I now have a feeling that in order to achieve 100% function coverage for C++ project, we would need to understand this so that I can invoke all those dtors in my unit tests.

I would greately appreciate if someone could give me the reply on the above.



GNU GCC (g++): Why does it generate multiple dtors?

I am trying to get a simple example to work to understand how to use `std::enable_if`. After I read [this answer][1], I thought it shouldn&#39;t be too hard to come up with a simple example. I want to use `std::enable_if` to choose between two member-functions and allow only one of them to be used.

Unfortunately, the following doesn&#39;t compile with gcc 4.7 and after hours and hours of trying I am asking you guys what my mistake is.

    #include &lt;utility&gt;
    #include &lt;iostream&gt;
    
    template&lt; class T &gt;
    class Y {
    
        public:
            template &lt; typename = typename std::enable_if&lt; true &gt;::type &gt;
            T foo() {
                return 10;
            }
            template &lt; typename = typename std::enable_if&lt; false &gt;::type &gt;
            T foo() {
                return 10;
            }
    
    };
    
    
    int main() {
        Y&lt; double &gt; y;
    
        std::cout &lt;&lt; y.foo() &lt;&lt; std::endl;
    }

gcc reports the following problems:

    % LANG=C make CXXFLAGS=&quot;-std=c++0x&quot; enable_if
    g++ -std=c++0x    enable_if.cpp   -o enable_if
    enable_if.cpp:12:65: error: `type&#39; in `struct std::enable_if&lt;false&gt;&#39; does not name a type
    enable_if.cpp:13:15: error: `template&lt;class T&gt; template&lt;class&gt; T Y::foo()&#39; cannot be overloaded
    enable_if.cpp:9:15: error: with `template&lt;class T&gt; template&lt;class&gt; T Y::foo()&#39;


Why doesn&#39;t g++ delete the wrong instantiation for the second member function? According to the standard, `std::enable_if&lt; bool, T = void &gt;::type` only exists when the boolean template parameter is true. But why doesn&#39;t g++ consider this as SFINAE? I think that the overloading error message comes from the problem that g++ doesn&#39;t delete the second member function and believes that this should be an overload.


  [1]: https://stackoverflow.com/questions/6627651/enable-if-method-specialization/6627748#6627748



std::enable_if to conditionally compile a member function

This C++ program is a CGI script, I have no desire to deal with exceptions. I&#39;d rather get a marginal performance boost and let the OS (Linux) handle cleanup after the process dies.

I am using the Standard C++ Library, and want any function to `die` like in Perl: **Whenever it throws an exception.** Without unwinding, *or running any further code* in my process.

How does -fno-exceptions work? If I have no catch at all in my code, and basically pretend like exceptions do no exist. but I **do** use std:: c++ library which **can** throw()?

Disabling C++ exceptions, how can I make any std:: throw() immediately terminate?

The below code works on Visual Studio 2008 with and without optimization. But it only works on g++ without optimization (O0).

    #include &lt;cstdlib&gt;
    #include &lt;iostream&gt;
    #include &lt;cmath&gt;

    double round(double v, double digit)
    {
        double pow = std::pow(10.0, digit);
        double t = v * pow;
        //std::cout &lt;&lt; &quot;t:&quot; &lt;&lt; t &lt;&lt; std::endl;
        double r = std::floor(t + 0.5);
        //std::cout &lt;&lt; &quot;r:&quot; &lt;&lt; r &lt;&lt; std::endl;
        return r / pow;
    }

    int main(int argc, char *argv[])
    {
        std::cout &lt;&lt; round(4.45, 1) &lt;&lt; std::endl;
        std::cout &lt;&lt; round(4.55, 1) &lt;&lt; std::endl;
    }

The output should be:

    4.5
    4.6

But g++ with optimization (`O1` - `O3`) will output:

    4.5
    4.5

If I add the `volatile` keyword before t, it works, so might there be some kind of optimization bug?

Test on g++ 4.1.2, and 4.4.4.

Here is the result on ideone:
http://ideone.com/Rz937

And the option I test on g++ is simple:

    g++ -O2 round.cpp

The more interesting result, even I turn on `/fp:fast` option on Visual Studio 2008, the result still is correct.

**Further question:**

I was wondering, should I always turn on the `-ffloat-store` option?

Because the g++ version I tested is **shipped with [CentOS][1]/[Red Hat Linux][2] 5 and CentOS/Redhat 6**.

I compiled many of my programs under these platforms, and I am worried it will cause unexpected bugs inside my programs. It seems a little difficult to investigate all my C++ code and used libraries whether they have such problems. Any suggestion?

Is anyone interested in why even `/fp:fast` turned on, Visual Studio 2008 still works? It seems like Visual&amp;nbsp;Studio&amp;nbsp;2008 is more reliable at this problem than g++?

  [1]: http://en.wikipedia.org/wiki/CentOS
  [2]: http://en.wikipedia.org/wiki/Red_Hat_Linux



Different floating point result with optimization enabled - compiler bug?

    #include &lt;vector&gt;
    
    struct A
    {
    	void foo(){}
    };
    
    template&lt; typename T &gt;
    void callIfToggled( bool v1, bool &amp;v2, T &amp; t )
    {
    	if ( v1 != v2 )
    	{
    		v2 = v1;
    		t.foo();
    	}
    }
    
    int main()
    {
    	std::vector&lt; bool &gt; v= { false, true, false };
    
    	const bool f = false;
    	A a;
    
    	callIfToggled( f, v[0], a );
    	callIfToggled( f, v[1], a );
    	callIfToggled( f, v[2], a );
    }

The compilation of the example above produces next error :  

    dk2.cpp: In function &#39;int main()&#39;:
    dk2.cpp:29:28: error: no matching function for call to &#39;callIfToggled(const bool&amp;, std::vector&lt;bool&gt;::reference, A&amp;)&#39;
    dk2.cpp:29:28: note: candidate is:
    dk2.cpp:13:6: note: template&lt;class T&gt; void callIfToggled(bool, bool&amp;, T&amp;)

I compiled using g++ (version 4.6.1) like this :  

    g++ -O3 -std=c++0x -Wall -Wextra -pedantic dk2.cpp

The question is why this happens? Is `vector&lt;bool&gt;::reference` not `bool&amp;`? Or is it a compiler&#39;s bug?  
Or, am I trying something stupid? :)

Content Type	Original Author	Original Content on Stackoverflow
Question	mrswmmr	View Question on Stackoverflow
Solution 1 - Path	Ernest Friedman-Hill	View Answer on Stackoverflow
Solution 2 - Path	Kartik Javali	View Answer on Stackoverflow
Solution 3 - Path	zyy	View Answer on Stackoverflow

How do I include a path to libraries in g++

Path Problem Overview

Path Solutions

Solution 1 - Path

Solution 2 - Path

Solution 3 - Path

How to check edittext's text is email address or not?

Get value of dynamically chosen class constant in PHP

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