The command

    echo | gcc -E -Wp,-v -

will show the include path in use.

I&#39;m not sure what you mean by the *recommended* way to find the include path.  The *standard* way is as given below (for c and c++):

    $ `gcc -print-prog-name=cc1` -v
    ignoring nonexistent directory &quot;/usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../x86_64-linux-gnu/include&quot;
    #include &quot;...&quot; search starts here:
    #include &lt;...&gt; search starts here:
     /usr/lib/gcc/x86_64-linux-gnu/4.7/include
     /usr/local/include
     /usr/lib/gcc/x86_64-linux-gnu/4.7/include-fixed
     /usr/include
    End of search list.
    ^C
    $ `gcc -print-prog-name=cc1plus` -v
    ignoring nonexistent directory &quot;/usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../x86_64-linux-gnu/include&quot;
    #include &quot;...&quot; search starts here:
    #include &lt;...&gt; search starts here:
     /usr/include/c++/4.7
     /usr/include/c++/4.7/x86_64-linux-gnu
     /usr/include/c++/4.7/backward
     /usr/lib/gcc/x86_64-linux-gnu/4.7/include
     /usr/local/include
     /usr/lib/gcc/x86_64-linux-gnu/4.7/include-fixed
     /usr/include
    End of search list.
    ^C



I want to get a `JSON` object from a Http get response:

Here is my current code for the Http get:

    protected String doInBackground(String... params) {

		HttpClient client = new DefaultHttpClient();
		HttpGet request = new HttpGet(params[0]);
		HttpResponse response;
		String result = null;
		try {
			response = client.execute(request);			
			HttpEntity entity = response.getEntity();
			
			if (entity != null) {

				// A Simple JSON Response Read
				InputStream instream = entity.getContent();
				result = convertStreamToString(instream);
				// now you have the string representation of the HTML request
				System.out.println(&quot;RESPONSE: &quot; + result);
				instream.close();
				if (response.getStatusLine().getStatusCode() == 200) {
					netState.setLogginDone(true);
				}

			}
			// Headers
			org.apache.http.Header[] headers = response.getAllHeaders();
			for (int i = 0; i &lt; headers.length; i++) {
				System.out.println(headers[i]);
			}
		} catch (ClientProtocolException e1) {
			// TODO Auto-generated catch block
			e1.printStackTrace();
		} catch (IOException e1) {
			// TODO Auto-generated catch block
			e1.printStackTrace();
		}
		return result;
	}

Here is the convertSteamToString function:

    private static String convertStreamToString(InputStream is) {
		
		BufferedReader reader = new BufferedReader(new InputStreamReader(is));
		StringBuilder sb = new StringBuilder();

		String line = null;
		try {
			while ((line = reader.readLine()) != null) {
				sb.append(line + &quot;\n&quot;);
			}
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				is.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		return sb.toString();
	}


Right now I am just getting a string object. How can I get a JSON object back.

Get a JSON object from a HTTP response

It seems easy to get the 

    From
    To
    Subject

etc via

    import email
    b = email.message_from_string(a)
    bbb = b[&#39;from&#39;]
    ccc = b[&#39;to&#39;]

assuming that `&quot;a&quot;` is the raw-email string which looks something like this.


    a = &quot;&quot;&quot;From root@a1.local.tld Thu Jul 25 19:28:59 2013
    Received: from a1.local.tld (localhost [127.0.0.1])
    	by a1.local.tld (8.14.4/8.14.4) with ESMTP id r6Q2SxeQ003866
    	for &lt;ooo@a1.local.tld&gt;; Thu, 25 Jul 2013 19:28:59 -0700
    Received: (from root@localhost)
    	by a1.local.tld (8.14.4/8.14.4/Submit) id r6Q2Sxbh003865;
    	Thu, 25 Jul 2013 19:28:59 -0700
    From: root@a1.local.tld
    Subject: oooooooooooooooo
    To: ooo@a1.local.tld
    Cc: 
    X-Originating-IP: 192.168.15.127
    X-Mailer: Webmin 1.420
    Message-Id: &lt;1374805739.3861@a1&gt;
    Date: Thu, 25 Jul 2013 19:28:59 -0700 (PDT)
    MIME-Version: 1.0
    Content-Type: multipart/mixed; boundary=&quot;bound1374805739&quot;
    
    This is a multi-part message in MIME format.
    
    --bound1374805739
    Content-Type: text/plain
    Content-Transfer-Encoding: 7bit
    
    ooooooooooooooooooooooooooooooooooooooooooooooo
    ooooooooooooooooooooooooooooooooooooooooooooooo
    ooooooooooooooooooooooooooooooooooooooooooooooo
    
    --bound1374805739--&quot;&quot;&quot;


**THE QUESTION**

 how do you get the `Body` of this email via python ?

So far this is the only code i am aware of but i have yet to test it.


    if email.is_multipart():
        for part in email.get_payload():
            print part.get_payload()
    else:
        print email.get_payload()

is this the correct way ?

or maybe there is something simpler such as...

    import email
    b = email.message_from_string(a)
    bbb = b[&#39;body&#39;]

?

Python : How to parse the Body from a raw email , given that raw email does not have a &quot;Body&quot; tag or anything

I&#39;m trying to programmatically find the `#include` path on Linux, which as I understand it, in practice means finding what GCC considers it to be. (Is that quite true? How does Clang do it?)

According to http://gcc.gnu.org/onlinedocs/cpp/Search-Path.html some of the components involve the CPU architecture and the GCC version; the latter in particular seems tricky; I suppose it could be obtained by running `gcc --version` and parsing the output (or `gcc -v`), but this seems inelegant at best and fragile at worst. Doing it from within one&#39;s code assuming one&#39;s program is being compiled with GCC might be another option, but it would require depending on that assumption.

What&#39;s the recommended way to do it?

Finding out what the GCC include path is

I'm trying to programmatically find the <code>#include</code> path on Linux, which as I understand it, in practice means finding what GCC considers it to be. (Is that quite true? How does Clang do it?)
According to <a href="http://gcc.gnu.org/onlinedocs/cpp/Search-Path.html" target="_blank" rel="noopener noreferrer">http://gcc.gnu.org/onlinedocs/cpp/Search-Path.html</a> some of the components involve the CPU architecture and the GCC version; the latter in particular seems tricky; I suppose it could be obtained by running <code>gcc --version</code> and parsing the output (or <code>gcc -v</code>), but this seems inelegant at best and fragile at worst. Doing it from within one's code assuming one's program is being compiled with GCC might be another option, but it would require depending on that assumption.
What's the recommended way to do it?

In Linux I want to add a daemon that cannot be stopped and which monitors filesystem changes.
If any changes are detected, it should write the path to the console where it was started plus a newline.

I already have the filesystem changing code almost ready but I cannot figure out how to create a daemon.

My code is from here: http://www.yolinux.com/TUTORIALS/ForkExecProcesses.html

What to do after the fork?

    int main (int argc, char **argv) {
    
      pid_t pID = fork();
      if (pID == 0)  {              // child
              // Code only executed by child process    
          sIdentifier = &quot;Child Process: &quot;;
        }
        else if (pID &lt; 0) {
            cerr &lt;&lt; &quot;Failed to fork&quot; &lt;&lt; endl;
            exit(1);
           // Throw exception
        }
        else                                   // parent
        {
          // Code only executed by parent process
     
          sIdentifier = &quot;Parent Process:&quot;;
        }	    
    
        return 0;
    }


Creating a daemon in Linux

Why does this code give the output `C++Sucks`? What is the concept behind it?

    #include &lt;stdio.h&gt;

    double m[] = {7709179928849219.0, 771};
    
    int main() {
        m[1]--?m[0]*=2,main():printf((char*)m);    
    }

Test it [here](http://ideone.com/JzpF8Q).

Concept behind these four lines of tricky C code

I would like to check if a given directory exists. I know how to do this on Windows: 

    BOOL DirectoryExists(LPCTSTR szPath)
    {
      DWORD dwAttrib = GetFileAttributes(szPath);
    
      return (dwAttrib != INVALID_FILE_ATTRIBUTES &amp;&amp; 
             (dwAttrib &amp; FILE_ATTRIBUTE_DIRECTORY));
    }

and Linux:

    DIR* dir = opendir(&quot;mydir&quot;);
    if (dir)
    {
        /* Directory exists. */
        closedir(dir);
    }
    else if (ENOENT == errno)
    {
        /* Directory does not exist. */
    }
    else
    {
        /* opendir() failed for some other reason. */
    }

But I need a portable way of doing this .. Is there any way to check if a directory exists no matter what OS Im using? Maybe C standard library way? 

**I know that I can use preprocessors directives and call those functions on different OSes but thats not the solution Im asking for.**

**I END UP WITH THIS, AT LEAST FOR NOW:**

    #include &lt;sys/types.h&gt;
    #include &lt;sys/stat.h&gt;
    #include &lt;stdio.h&gt;
    #include &lt;stdlib.h&gt;
    
    int dirExists(const char *path)
    {
        struct stat info;
    
        if(stat( path, &amp;info ) != 0)
            return 0;
        else if(info.st_mode &amp; S_IFDIR)
            return 1;
        else
            return 0;
    }
    
    int main(int argc, char **argv)
    {
        const char *path = &quot;./TEST/&quot;;
        printf(&quot;%d\n&quot;, dirExists(path));
        return 0;
    }



Portable way to check if directory exists [Windows/Linux, C]

Is it true that the first C compiler was written in C itself? Then, how was it executed and compiled? Or, was this compiler written in assembly language?


How was the first C compiler written?

Many of the books that I am reading use keyword `const` when the value of a variable should not be modified. Apart from specifying to readers of the code that you may cause errors if you modify this variable (you can use comments to do this), why would you need that keyword to be a part of any programming language? It seems to me that if you don&#39;t want a variable modified, simply don&#39;t.

Could someone clarify this for me? 

Why would you use the keyword const if you already know variable should be constant?

I tried to make an &quot;alias&quot; for a path that I use often while shell scripting. I tried something, but it failed: 

    myFold=&quot;~/Files/Scripts/Main&quot;
    cd myFold
    
    bash: cd: myFold: No such file or directory

How do I make it work ?  
However, `cd ~/Files/Scripts/Main`works.



How to make an &quot;alias&quot; for a long path?

In linux I could find the mysql installation directory with the command `which mysql`. But I could not find any in windows. I tried `echo %path%` and it resulted many paths along with path to mysql bin. 

I wanted to find the mysql data directory from command line in windows for use in batch program. I would also like to find mysql data directory from linux command line. Is it possible? or how can we do that?

In my case, the mysql data directory is on the installation folder i.e. `..MYSQL\mysql server 5\data` It might be installed on any drive however. I want to get it returned from the command line.


How to find the mysql data directory from command line in windows

I&#39;m trying to make a shell script which should be used like this:

    ocrscript.sh -from /home/kristoffer/test.png -to /home/kristoffer/test.txt

The script will then ocr convert the image file to a text file. Here is what I have come up with so far:

    #!/bin/bash
    export HOME=/home/kristoffer
    /usr/local/bin/abbyyocr9 -rl Swedish -if ???fromvalue??? -of ???tovalue??? 2&gt;&amp;1

But I don&#39;t know how to get the `-from` and `-to` values. Any ideas on how to do it?

Script parameters in Bash

I want to copy the contents of five files to one file as is. I tried doing it using cp for each file. But that overwrites the contents copied from the previous file. I also tried 

    paste -d &quot;\n&quot; 1.txt 0.txt

and it did not work.

I want my script to add the newline at the end of each text file.

eg. Files 1.txt, 2.txt, 3.txt. Put contents of 1,2,3 in 0.txt

How do I do it ?


How to append contents of multiple files into one file

I have the following simplified code:

    #include &lt;stdio.h&gt;
    int main () 
    {
    	printf(&quot;Hello &quot;);
    	goto Cleanup;
    Cleanup:
    	char *str = &quot;World\n&quot;;
    	printf(&quot;%s\n&quot;, str);
    }

I get an error because a new variable is declared after the label. If I put the content (mainly initialization) after the label in a {} block, compilation succeeds.

I think I understand the reason for the block in case of a switch, but why should it be applicable in case of a label ?

This error is from a gcc compiler




Why do I get &quot;a label can only be part of a statement and a declaration is not a statement&quot; if I have a variable that is initialized after a label?

Here is a piece of code in `/usr/src/linux-3.10.10-1-ARCH/include/linux/printk.h`:

    static inline int printk_get_level(const char *buffer)
    {
      if (buffer[0] == KERN_SOH_ASCII &amp;&amp; buffer[1]) {
        switch (buffer[1]) {
        case &#39;0&#39; ... &#39;7&#39;:
        case &#39;d&#39;:  /* KERN_DEFAULT */
          return buffer[1];
        }
      }
    }

Is it a kind of operator? Why does &quot;The C Programming Language&quot; not mention it?

What is &quot;...&quot; in switch-case in C code

Why does the **C** preprocessor in **GCC** interpret the word `linux` (small letters) as the constant `1`?

**test.c:**

    #include &lt;stdio.h&gt;
    int main(void)
    {       
        int linux = 5;
        return 0;
    }


Result of `$ gcc -E test.c` (stop after the preprocessing stage):

    ....
    int main(void)
    {
        int 1 = 5;
        return 0;
    }

Which of course yields an error.

(BTW: There is no `#define linux` in the `stdio.h` file.)


Why does the C preprocessor interpret the word &quot;linux&quot; as the constant &quot;1&quot;?

I&#39;m trying to compile this source code from the makefile in a VPS, but its not working. The VPS is a 64 Cent OS

Here&#39;s the full error

    # make
    gcc -c -O3 -w -DLINUX -I../SDK/amx/ ../SDK/amx/*.c
    g++ -c -O3 -w -DLINUX -I../SDK/amx/ ../SDK/*.cpp
    g++ -c -O3 -w -DLINUX -I../SDK/amx/ *.cpp
    g++ -O2 -fshort-wchar -shared -o &quot;TCP_V1.so&quot; *.o
    /usr/bin/ld: TCP-LINUX_V1.o: relocation R_X86_64_32 against `.rodata.str1.8&#39; can not be     used when making a shared object; recompile with -fPIC
    TCP-LINUX_V1.o: could not read symbols: Bad value
    collect2: ld returned 1 exit status
    make: *** [all] Error 1

Here&#39;s my makefile:

    GPP=g++
    GCC=gcc
    OUTFILE=&quot;TCP_V1.so&quot;

    COMPILE_FLAGS=-c -O3 -w -DLINUX -I../SDK/amx/

    all:
	    $(GCC) $(COMPILE_FLAGS) ../SDK/amx/*.c
	    $(GPP) $(COMPILE_FLAGS) ../SDK/*.cpp
	    $(GPP) $(COMPILE_FLAGS) *.cpp
	    $(GPP) -O2 -fshort-wchar -shared -o $(OUTFILE) *.o

Anyone know what&#39;s wrong?


Compilation fails with &quot;relocation R_X86_64_32 against `.rodata.str1.8&#39; can not be used when making a shared object&quot;

I&#39;m new to the field of microcontrollers. I need to port an IDE which is compiling programs for AVR microcontrollers to compile programs for ARM microcontrollers. I have just replaced the compiler from AVR to ARM and added some options as told by someone.
The following is the command:

    \ARM-GCC\bin\arm-none-eabi-gcc -O0 -ffunction-sections -Wall -std=gnu99 -mfloat-abi=soft 
    -Wa,-adhlns=&quot;$@.lst&quot; -fmessage-length=0 -mcpu=cortex-m0 -mthumb -g3 -gdwarf-2 -Wl,
    --gc-sections -o &lt;Dir_name&gt;\Build_Files\Blink_arm.cpp.elf  &lt;Dir_name&gt;\Build_Files\Blink_arm.cpp.o &lt;Dir_name&gt;\Build_Files\core.a 
    -L&lt;Dir_name&gt;\Build_Files -lm 


When I execute it I get the follwing error:

    tools/arm-gcc/bin/../lib/gcc/arm-none-eabi/4.6.2\libc.a(lib_a-exit.o): In function `exit&#39;:
    exit.c:(.text+0x18): undefined reference to `_exit&#39;  
    collect2: ld returned 1 exit status

May I get some help on what is this error and how can I solve it. And also I don&#39;t know what those options in the command line specify.

exit.c:(.text+0x18): undefined reference to `_exit&#39; when using arm-none-eabi-gcc

The standard array-size macro that is often taught is

    #define ARRAYSIZE(arr) (sizeof(arr) / sizeof(arr[0]))

or some equivalent formation. However, this kind of thing silently succeeds when a pointer is passed in, and gives results that can seem plausible at runtime until things mysteriously fall apart.

It&#39;s all-too-easy to make this mistake: a function that has a local array variable is refactored, moving a bit of array manipulation into a new function called with the array as a parameter.

So, the question is: is there a &quot;sanitary&quot; macro to detect misuse of the `ARRAYSIZE` macro in C, preferably at compile-time? In C++ we&#39;d just use a template specialized for array arguments only; in C, it seems we&#39;ll need some way to distinguish arrays and pointers. (If I wanted to reject arrays, for instance, I&#39;d just do e.g. `(arr=arr, ...)` because array assignment is illegal).

Array-size macro that rejects pointers

    #define DEFINE_STAT(Stat) \
	struct FThreadSafeStaticStat&lt;FStat_##Stat&gt; StatPtr_##Stat;

The above line is take from Unreal 4, and I know I could ask it over on the unreal forums, but I think this is a general C++ question that warrants being asked here.

I understand the first line defines a macro, however I am not well versed in preprocessor shenanigans in C++ and so I&#39;m lost over there. Logic tells me the backslash means the declaration continues onto the next line.

FThreadSafeStaticStat looks a bit like a template, but there&#39;s #&#39;s going on in there and a syntax I&#39;ve never seen before in C++

Could someone tell me what this means? I understand that you may not have access to Unreal 4, but it&#39;s just the syntax I don&#39;t understand.

What does ## (double hash) do in a preprocessor directive?

At the top of my file I have

    #define AGE &quot;42&quot;

Later in the file I use ID multiple times including some lines that look like

    std::string name = &quot;Obama&quot;;
    std::string str = &quot;Hello &quot; + name + &quot; you are &quot; + AGE + &quot; years old!&quot;;
    str += &quot;Do you feel &quot; + AGE + &quot; years old?&quot;;

I get the error:

&gt; &quot;error: invalid operands of types ‘const char [35]’ and ‘const char [2]’ to binary ‘operator+’&quot;

on line 3. I did some research and found it was because of how C++ was treating the different strings and was able to fix it by changing &quot;AGE&quot; to &quot;string(AGE).&quot; However, I accidentally missed one of the instances until today and was wondering why the compiler wasn&#39;t complaining even though I still had an instance where it was just &quot;AGE&quot;.

Through some trial and error I found that I only need `string(AGE)` on lines where I don&#39;t concatenate another string that was created in the function body.

My questions is &quot;what is going on in the background that C++ doesn&#39;t like concatenating a string with a string put there by the preprocessor unless you are also concatenating string that you defined in the function.&quot;



Error: invalid operands of types ‘const char [35]’ and ‘const char [2]’ to binary ‘operator+’

I want to know how the **C** preprocessor handles circular dependencies (of #defines). This is my program: 


    #define ONE TWO 
    #define TWO THREE
    #define THREE ONE
    
    int main()
    {
    	int ONE, TWO, THREE;
    	ONE = 1;
    	TWO = 2;
    	THREE = 3;
    	printf (&quot;ONE, TWO, THREE = %d,  %d, %d \n&quot;,ONE,  TWO, THREE);
    }


Here is the preprocessor output. I&#39;m unable to figure out why the output is as such. I would like to know the various steps a preprocessor takes in this case to give the following output.


    # 1 &quot;check_macro.c&quot;
    # 1 &quot;&lt;built-in&gt;&quot;
    # 1 &quot;&lt;command-line&gt;&quot;
    # 1 &quot;check_macro.c&quot;
    
    int main()
    {
     int ONE, TWO, THREE;
     ONE = 1;
     TWO = 2;
     THREE = 3;
     printf (&quot;ONE, TWO, THREE = %d,  %d, %d \n&quot;,ONE, TWO, THREE);
    }


I&#39;m running this program on linux 3.2.0-49-generic-pae and compiling in gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5).


Content Type	Original Author	Original Content on Stackoverflow
Question	rwallace	View Question on Stackoverflow
Solution 1 - C	caf	View Answer on Stackoverflow
Solution 2 - C	devnull	View Answer on Stackoverflow

Finding out what the GCC include path is

C Problem Overview

C Solutions

Solution 1 - C

Solution 2 - C

Python : How to parse the Body from a raw email , given that raw email does not have a "Body" tag or anything

Get a JSON object from a HTTP response

Attributions