They come from C AFAIR from times when it was not known what special symbols are on the keyboard. So to have portable language they were defined so anyone can use C even if they used keyboard with no `&amp;`, `|`, or `^` (etc.).

Nowadays when QWERTY is a standard (with AZWERTY &amp; co. as variations) it is no longer an issue.

PS. And of course for obfuscation code competitions ;)

I&#39;d like to ask your help on a longstanding issue with php/mysql connections.

Every time I execute a &quot;SHOW PROCESSLIST&quot; command it shows me about 400 idle (Status: Sleep) connections to the database Server emerging from our 5 Webservers.

That never was much of a problem (and I didn&#39;t find a quick solution) until recently traffic numbers increased and since then MySQL reports the &quot;to many connections&quot; Problems repeatedly, even so 350+ of those connections  are in &quot;sleep&quot; state. Also a server can&#39;t get a MySQL connection even if there are sleeping connection to that same server.

All those connections vanish when an apache server is restated.

The PHP Code used to create the Database connections uses the normal &quot;mysql&quot; Module, the &quot;mysqli&quot; Module, PEAR::DB and Zend Framework Db Adapter. (Different projects). NONE of the projects uses persistent connections.

Raising the connection-limit is possible but doesn&#39;t seem like a good solution since it&#39;s 450 now and there are only 20-100 &quot;real&quot; connections at a time anyways.

My question: 

Why are there so many connections in sleep state and how can I prevent that?

-- Update:

The Number of Apache requests running at a time never exceeds 50 concurrent requests, so i guess there is a problem with closing the connection or apache keeps the port open without a phpscript attached or something (?)


my.cnf in case it&#39;s helpful:

    innodb_buffer_pool_size = 1024M
    
    max_allowed_packet = 5M
    net_buffer_length = 8K
    
    read_buffer_size = 2M
    read_rnd_buffer_size = 8M
    
    query_cache_size = 512M
    myisam_sort_buffer_size = 128M
    
    max_connections = 450
    thread_cache = 50
    key_buffer_size = 1280M
    join_buffer_size = 16M
    
    table_cache = 2048
    sort_buffer_size = 64M
    tmp_table_size = 512M
    max_heap_table_size = 512M
    
    thread_concurrency = 8
    
    log-slow-queries = /daten/mysql-log/slow-log
    long_query_time = 1
    log_queries_not_using_indexes
    
    innodb_additional_mem_pool_size = 64M
    innodb_log_file_size = 64M
    innodb_log_buffer_size = 8M
    innodb_flush_log_at_trx_commit = 2
    innodb_file_per_table


MySql Proccesslist filled with &quot;Sleep&quot; Entries leading to &quot;Too many Connections&quot;?

I&#39;d like to retrieve the GCC version used to compile a given executable. I tried `readelf` but didn&#39;t get the information. Any thoughts?

How to retrieve the GCC version used to compile a given ELF executable?

&gt; **Possible Duplicate:**  
&gt; [The written versions of the logical operators.](https://stackoverflow.com/questions/2376448/the-written-versions-of-the-logical-operators)  

&lt;!-- End of automatically inserted text --&gt;

I notice that C++ define keyword `and`, `or`, `not`, `xor`, `and_eq`, `or_eq`, `not_eq` and `xor_eq` as an alternative to `&amp;&amp;`, `||`, `!`, `^`, `&amp;=`, `|=`, `!=` and `|=`. and they&#39;re rarely used! What&#39;s wrong? Are they not portable?

C++ and,or,not,xor keywords

> Possible Duplicate: 
> <a href="https://stackoverflow.com/questions/2376448/the-written-versions-of-the-logical-operators" target="_blank" rel="noopener noreferrer">The written versions of the logical operators.</a>

I notice that C++ define keyword <code>and</code>, <code>or</code>, <code>not</code>, <code>xor</code>, <code>and_eq</code>, <code>or_eq</code>, <code>not_eq</code> and <code>xor_eq</code> as an alternative to <code>&#x26;&#x26;</code>, <code>||</code>, <code>!</code>, <code>^</code>, <code>&#x26;=</code>, <code>|=</code>, <code>!=</code> and <code>|=</code>. and they're rarely used! What's wrong? Are they not portable?

Is there an easy way to remove comments from a C/C++ source file without doing any preprocessing. (ie, I think you can use gcc -E but this will expand macros.) I just want the source code with comments stripped, nothing else should be changed.



EDIT:

Preference towards an existing tool. I don&#39;t want to have to write this myself with regexes, I foresee too many surprises in the code.

Remove comments from C/C++ code

I&#39;m having trouble with the linking of my files.

Basically, my program consists of:

 - The main program, `gen1`.
 - `gen1` - receives input sends to `str2value` for
   processing, outputs results `str2value`, breaks input into tokens
   using &quot;tokenizer&quot; determines what sort of processing to do to each
   token, and passes them off to `str2num`, or `str2cmd`. It then returns an
   array of the results.
 - `str2num` - does some processing
 - `str2cmd` - ditto
 - `author.py` - a python script that generates `str2cmd.c` and `str2cmd.h` from a header `cmdTable.h`.


I&#39;m pretty sure I have my includes right, I&#39;ve checked a couple of times. I&#39;ve also checked that there are no conditions `#ifndef` wrong in the headers.


Here is my Makefile:

    #CPP = g++ -lserial
    CPP = g++ -DTESTMODE
    C= gcc
    DEFINES = LURC
    CFLAGS = -Wall -fshort-enums -D$(DEFINES)
    PROJECTFILES = gen1.cpp str2value.o
    
    STR2VALUEFILES = str2value.cpp str2cmd.o str2num.o tokenizer.o str2value.h
    
    gen1 : $(PROJECTFILES)
            $(CPP) $(CFLAGS) -o gen1 $(PROJECTFILES)
    
    
    
    str2value.o : $(STR2VALUEFILES)
    #       echo &quot;str2value&quot;
            $(CPP) $(CFLAGS) -c $(STR2VALUEFILES)
    
    str2num.o: str2num.cpp  str2value.h str2num.hpp
             $(C) $(CFLAGS) -c $^
    
    
    tokenizer.o: tokenizer.cpp tokenizer.hpp
            $(CPP) $(CFLAGS) -c $^
    
    str2cmd.o : authorCMDs.py cmdTable.h
            python authorCMDs.py cmdTable.h str2cmd #this uses the gcc -E cmdTable.h -DLURC
            $(C) $(CFLAGS) -c str2cmd.c str2cmd.h
    
    #TODO: add a thing that checks str2cmd.h/.c has not been modified by hand
   
    
    
    .PHONEY: clean
    clean:
            rm *.o
    
    .PHONEY: all
    all:
            clear
            make clean
            make

Here is the output I recieve from make all:

    make clean
    make[1]: Entering directory `/home/frames/LURC/gen1/gen1Source&#39;
    rm *.o
    make[1]: Leaving directory `/home/frames/LURC/gen1/gen1Source&#39;
    make
    make[1]: Entering directory `/home/frames/LURC/gen1/gen1Source&#39;
    python authorCMDs.py cmdTable.h str2cmd #this uses the gcc -E cmdTable.h -DLURC
    str2cmd.c and str2cmd.h, generated from cmdTable.h
    
    gcc  -Wall -fshort-enums -DLURC -c str2cmd.c str2cmd.h
    gcc  -Wall -fshort-enums -DLURC -c str2num.cpp str2value.h str2num.hpp
    g++ -DTESTMODE -Wall -fshort-enums -DLURC -c tokenizer.cpp tokenizer.hpp
    g++ -DTESTMODE -Wall -fshort-enums -DLURC -c str2value.cpp str2cmd.o str2num.o tokenizer.o str2value.h
    g++: str2cmd.o: linker input file unused because linking not done
    g++: str2num.o: linker input file unused because linking not done
    g++: tokenizer.o: linker input file unused because linking not done
    g++ -DTESTMODE -Wall -fshort-enums -DLURC -o gen1 gen1.cpp str2value.o
    str2value.o: In function `getValue(char*)&#39;:
    str2value.cpp:(.text+0xbd): undefined reference to `str2cmd(char*)&#39;
    str2value.cpp:(.text+0x102): undefined reference to `str2num(char*)&#39;
    str2value.o: In function `getAllValues(char*)&#39;:
    str2value.cpp:(.text+0x164): undefined reference to `tokenizer::tokenizer(char*)&#39;
    str2value.cpp:(.text+0x177): undefined reference to `tokenizer::getNumTokens(char const*)&#39;
    str2value.cpp:(.text+0x1a9): undefined reference to `tokenizer::getNextToken(char const*)&#39;
    str2value.cpp:(.text+0x1e9): undefined reference to `tokenizer::getNumTokens(char const*)&#39;
    str2value.cpp:(.text+0x201): undefined reference to `tokenizer::~tokenizer()&#39;
    str2value.cpp:(.text+0x25b): undefined reference to `tokenizer::~tokenizer()&#39;
    collect2: ld returned 1 exit status
    make[1]: *** [gen1] Error 1
    make[1]: Leaving directory `/home/frames/LURC/gen1/gen1Source&#39;
    make: *** [all] Error 2

Any suggestions about what this is about? `STR2VALUESFILES` has all the object files I need, to define the missing functions.

Linker error: &quot;linker input file unused because linking not done&quot;, undefined reference to a function in that file

The goal is to access the &quot;nth&quot; element of a vector of strings instead of the [] operator or the &quot;at&quot; method. From what I understand, iterators can be used to navigate through containers, but I&#39;ve never used iterators before, and what I&#39;m reading is confusing.

If anyone could give me some information on how to achieve this, I would appreciate it. Thank you.

How to navigate through a vector using iterators? (C++)

I heard there is a possibility to enable google-test TestCase classes friends to my classes, thus enabling tests to access my private/protected members.

How to accomplish that?


How to make google-test classes friends with my classes?

What is _undefined behavior_ (UB) in C and C++?  What about _unspecified behavior_ and _implementation-defined_ behavior?  What is the difference between them?

Undefined, unspecified and implementation-defined behavior

Apparently a colon is used in multiple ways in Java. Would anyone mind explaining what it does?

For instance here:

	String cardString = &quot;&quot;;
	for (PlayingCard c : this.list)  // &lt;--
	{
		cardString += c + &quot;\n&quot;;
	}

How would you write this `for-each` loop a different way so as to not incorporate the `:`?

What does the colon (:) operator do?

Why is === faster than == in PHP?

The `instanceof` keyword in JavaScript can be quite confusing when it is first encountered, as people tend to think that JavaScript is not an object-oriented programming language.

 - What is it?
 - What problems does it solve?
 - When is it appropriate and when not?

What is the instanceof operator in JavaScript?

I ran across the caret operator in python today and trying it out, I got the following output:

    &gt;&gt;&gt; 8^3
    11
    &gt;&gt;&gt; 8^4
    12
    &gt;&gt;&gt; 8^1
    9
    &gt;&gt;&gt; 8^0
    8
    &gt;&gt;&gt; 7^1
    6
    &gt;&gt;&gt; 7^2
    5
    &gt;&gt;&gt; 7^7
    0
    &gt;&gt;&gt; 7^8
    15
    &gt;&gt;&gt; 9^1
    8
    &gt;&gt;&gt; 16^1
    17
    &gt;&gt;&gt; 15^1
    14
    &gt;&gt;&gt;

It seems to be based on 8, so I&#39;m guessing some sort of byte operation?  I can&#39;t seem to find much about this searching sites other than it behaves oddly for floats, does anybody have a link to what this operator does or can you explain it here?

What does the caret (^) operator do?

What do you call this arrow looking `-&gt;` operator found in PHP? 

It&#39;s either a minus sign, dash or hyphen followed by a greater than sign (or right chevron). 

How do you pronounce it when reading code out loud?

Content Type	Original Author	Original Content on Stackoverflow
Question	uray	View Question on Stackoverflow
Solution 1 - C++	Maciej Piechotka	View Answer on Stackoverflow

C++ and,or,not,xor keywords

C++ Problem Overview

C++ Solutions

Solution 1 - C++

How to retrieve the GCC version used to compile a given ELF executable?

MySql Proccesslist filled with "Sleep" Entries leading to "Too many Connections"?

Attributions