While compiling a simple or complicated c++ program in Cygwin/g++ if you get below error
/usr/lib/gcc-lib/i686-pc-cygwin/2.95.2-6/../../../../i686-pc-cygwin/bin/ld: cannot find -lstdc++
collect2: ld returned 1 exit status
Go though following steps.
First try to find where you /usr/lib is mapped. Use Cygpath -w /usr/lib
Above command would tell you the windows directory path where /usr/local/lib is mapped. Go to that directory. In my case it was c:\utils\cygwin\lib. cd into this directory. And search for file libstdc*. You would get a file named libstdc++.a.2.10.0. Create a link named libstdc++.a for the same file in this directory. Here is sequence of commands.
C:\> Cygpath -w /usr/lib
c:\utils\cygwin\lib
C:\>cd c:\utils\cygwin\lib
C:\utils\Cygwin\lib>ls libstdc++*
libstdc++.a.2.10.0
C:\utils\Cygwin\lib>ln -s libstdc++.a.2.10.0 libstdc++.a
And thats it. And even if above trick does not work, try creating link to libstdc++ in directory given by cygpath -w /usr/local/lib.
The problem is g++ can not find out libstdc++ on its own, it needs to be told about this. Here are more threads on this.
http://ubuntuforums.org/archive/index.php/t-15120.html
http://gcc.gnu.org/ml/libstdc++/2002-05/msg00353.html
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Wednesday, March 28, 2007
Monday, March 26, 2007
Undefined referrence to 'vtable for MyWidget'
So I have started learning QT on my own. Documentation for QT seems just fabulous. So today I am in tutorial number 4, and here as exercise I created a basic signal and slot. But I got this error .. undefined reference to `vtable for MyWidget'
I had put the class definion in my .cpp file and was struggling to get it compiled. But it would never compile and throw above compiler error along with some other random erros. When I googled, I got below link
http://www.qtforum.org/article/302/Fixing-undefined-reference-to-vtable-.html
Sometimes the linking stage of compiling might fail with the rather confusing error:
undefined reference to `vtable for MyWidget`
So theme is don't put class definitions in .cpp files when they have the Q_OBJECT macro.
I had put the class definion in my .cpp file and was struggling to get it compiled. But it would never compile and throw above compiler error along with some other random erros. When I googled, I got below link
http://www.qtforum.org/article/302/Fixing-undefined-reference-to-vtable-.html
Sometimes the linking stage of compiling might fail with the rather confusing error:
undefined reference to `vtable for MyWidget`
So theme is don't put class definitions in .cpp files when they have the Q_OBJECT macro.
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Darwin Server from Apple.
I was trying to install and use Apple's free Darwin Streaming Server on WinXP. But got into lot of troubles. There were many hit and trials which helped me setup the server.
(1) You need to install DSS. Once it is installed, it would ask you to create admin user name and password. Do that. If all is okay it would start the server. In my case it was not so I had to close the command prompt window [because of perl]
(2) Since I have Cygwin on my machine [The very reason my QT cant be compiled ;)] I could not install DSS, since it works only with Active Perl. So I had to install Active Perl and then had to remove " Cygwin Perl"'s path from my Path.
(3) Then associated "Active Perl" with all .pl files through file assocication. This is not a problem once Cygwin Perl is removed from path and you click on some .pl files, windows would automatically ask you which program to select to run this. Just choose Active Perl.
(4) On two command prompts I had to run DarwinStreamingServer.exe -d [NOTE :: DONT forget "-d" option from command prompt] and streamingadminserver.pl.
(5) Now your server is up and in your web browser you can type http://your.ip.add.ress:1220. It would open DSS Server Admin. Enter your userid and password which you created in step (1).
(6) Now comes streaming part. Remember that by default your media directory is c:\Program Files\Darwin Streaming Server\Movies\. So in case you want to stream some mp3 files put them here. Also dont forget to go to "Port Settings" and enable Port 80, in case you are behind firewall and intend to listen to this server from outside your LAN.
(7) Create Playlists. Go to Playlists on your left pane, click on "New MP3 Playlist", give your playlist name like "sample" and give it a mount point "sample". Now you would see all the mp3 files below it. Add the files you want to add.
(8) Now dont forget to choose your Playmode. NEVER set it as sequential. Or else once all the songs are played, there would not be any thing on your server. I chose "Sequential Looped". And thats it!
(9) Go to Winamp and type http://your.ip.add.ress/sample and you would listen the songs.
Foolishness which I did :- Created a mount point "/", added one file called "sample.mp3", chose the play method as "Sequential" and was trying to access http://my.ip.add.ress/sample.mp3, which of course would not work!
Now I would try to set up straming movies server and then would see if it works too! Meanwhile I have thought of bringing precompiled QT libs from my home laptop and put them on my office PC to see if QT can then be make workable!
(1) You need to install DSS. Once it is installed, it would ask you to create admin user name and password. Do that. If all is okay it would start the server. In my case it was not so I had to close the command prompt window [because of perl]
(2) Since I have Cygwin on my machine [The very reason my QT cant be compiled ;)] I could not install DSS, since it works only with Active Perl. So I had to install Active Perl and then had to remove " Cygwin Perl"'s path from my Path.
(3) Then associated "Active Perl" with all .pl files through file assocication. This is not a problem once Cygwin Perl is removed from path and you click on some .pl files, windows would automatically ask you which program to select to run this. Just choose Active Perl.
(4) On two command prompts I had to run DarwinStreamingServer.exe -d [NOTE :: DONT forget "-d" option from command prompt] and streamingadminserver.pl.
(5) Now your server is up and in your web browser you can type http://your.ip.add.ress:1220. It would open DSS Server Admin. Enter your userid and password which you created in step (1).
(6) Now comes streaming part. Remember that by default your media directory is c:\Program Files\Darwin Streaming Server\Movies\. So in case you want to stream some mp3 files put them here. Also dont forget to go to "Port Settings" and enable Port 80, in case you are behind firewall and intend to listen to this server from outside your LAN.
(7) Create Playlists. Go to Playlists on your left pane, click on "New MP3 Playlist", give your playlist name like "sample" and give it a mount point "sample". Now you would see all the mp3 files below it. Add the files you want to add.
(8) Now dont forget to choose your Playmode. NEVER set it as sequential. Or else once all the songs are played, there would not be any thing on your server. I chose "Sequential Looped". And thats it!
(9) Go to Winamp and type http://your.ip.add.ress/sample and you would listen the songs.
Foolishness which I did :- Created a mount point "/", added one file called "sample.mp3", chose the play method as "Sequential" and was trying to access http://my.ip.add.ress/sample.mp3, which of course would not work!
Now I would try to set up straming movies server and then would see if it works too! Meanwhile I have thought of bringing precompiled QT libs from my home laptop and put them on my office PC to see if QT can then be make workable!
Thursday, March 22, 2007
RGB Vs YCbCr , Static Globals not allowed in BREW
RGB Vs. YCbCr
I presume you know RGB. Any image is made up of two components, brightness and color information. Brightness information is high frequency information and color is low frequency information. Human Visual System (HVS) is more sensitive to brightness then color. Means it can identify brightness more better then change in color.
Chroma is the color information of the picture. It is determined by seperating luma (Y) value from blue and red signal. If you need a quick formula here it is
For taking advantage of this YCbCr model was developed. In this Y is calculated from weighted R, G and B. And then Cb and Cr are calculated. Then Cb and Cr are comressed more aggresively then Y.
If same principle [compressing low frequency color information] is applied to RGB model, image would not be of that quality as of JPEG. This is the difference of RGB and YCbCr.
Sources
http://www.impulseadventure.com/photo/jpeg-color-space.html
http://en.wikipedia.org/wiki/Ycbcr
Why static and global varibles in BREW dynamic apps are not allowed ?
Very crude reason : There is no data section in .mod files created by BREW. Static variables are allocated in data segment of programme. And they are offseted from a global "SB" static base register. Now BREW loads application anywhere in memory so if it were to allow static variables it would have to remember SB for evey applet which apparently BREW does not want to do. Though there are some hacks for it. For more information search BREW forums @ Qualcomm.com
Meanwhile Linux server in our company location is still not up and I am waiting for it to compile my QT code.
I presume you know RGB. Any image is made up of two components, brightness and color information. Brightness information is high frequency information and color is low frequency information. Human Visual System (HVS) is more sensitive to brightness then color. Means it can identify brightness more better then change in color.
Chroma is the color information of the picture. It is determined by seperating luma (Y) value from blue and red signal. If you need a quick formula here it is
For taking advantage of this YCbCr model was developed. In this Y is calculated from weighted R, G and B. And then Cb and Cr are calculated. Then Cb and Cr are comressed more aggresively then Y.
If same principle [compressing low frequency color information] is applied to RGB model, image would not be of that quality as of JPEG. This is the difference of RGB and YCbCr.
Sources
http://www.impulseadventure.com/photo/jpeg-color-space.html
http://en.wikipedia.org/wiki/Ycbcr
Why static and global varibles in BREW dynamic apps are not allowed ?
Very crude reason : There is no data section in .mod files created by BREW. Static variables are allocated in data segment of programme. And they are offseted from a global "SB" static base register. Now BREW loads application anywhere in memory so if it were to allow static variables it would have to remember SB for evey applet which apparently BREW does not want to do. Though there are some hacks for it. For more information search BREW forums @ Qualcomm.com
Meanwhile Linux server in our company location is still not up and I am waiting for it to compile my QT code.
Friday, March 16, 2007
Telnet to Internet ?
I am still waiting for IT Ops to respond to my problem of not being able to compile any simple program on the linux server. Meanwhile I thought that is there a big server on internet where I can login and run my QT applications ! So again I googled it and I got a link about this.
But the servers mentioned there were too out of date. So I again used google to find out Free Linux Shell Account.
Lets see if something works out here! But list here seems to be quite latest. I tried the a/c available with http://www.freeshell.org. It is pretty simple you just type the command telnet tty.freeshell.org on your command prompt. If you are a new user type in "new" post some text screens which you should read you would be able to create your linux a/c. So even if you are using Windows, dont have Linux installed but want to learn some basic Unix this is great!
But you can not use all the commands on this server unless you give around 5 USD to them. Also you can not do stuff like exporting display on the server to your local machine and then launching some graphics application like Netscape navigator or any thing. That means I can not run my QT applications there, even if I am able to somehow put my QT there. Too bad! So let me stop this thread, but I learnt some thing new today ... and served the basic purpose of this blog.
Next three days we have a big week end so may be I would not be learning anything new on next three days :)
But the servers mentioned there were too out of date. So I again used google to find out Free Linux Shell Account.
Lets see if something works out here! But list here seems to be quite latest. I tried the a/c available with http://www.freeshell.org. It is pretty simple you just type the command telnet tty.freeshell.org on your command prompt. If you are a new user type in "new" post some text screens which you should read you would be able to create your linux a/c. So even if you are using Windows, dont have Linux installed but want to learn some basic Unix this is great!
But you can not use all the commands on this server unless you give around 5 USD to them. Also you can not do stuff like exporting display on the server to your local machine and then launching some graphics application like Netscape navigator or any thing. That means I can not run my QT applications there, even if I am able to somehow put my QT there. Too bad! So let me stop this thread, but I learnt some thing new today ... and served the basic purpose of this blog.
Next three days we have a big week end so may be I would not be learning anything new on next three days :)
Thursday, March 15, 2007
Mocha X-Server
After googling a bit I got mocha X server which is entirely free. AND WOW!!!! it is perfect so far !! pretty fast ... simple installation! great .. just download it from http://www.newfreedownloads.com/download-Mocha-X-Server.html and there you go. If you find this link dead! search google for it. IF that also fails put a comment on this blog and I may help you get this binary!
Now another problem. Looks like I need root permission to install QT under Linux ! At least thats what the INSTALL file says. It says ..
So I posted this question on QT news group and got a very quick and early response. They told me that I can use ./configure
Now another problem. Looks like I need root permission to install QT under Linux ! At least thats what the INSTALL file says. It says ..
To install the library, demos, examples, tools, and tutorials,
type: su -c "make install" Obviosuly this would need root permission which I dont have. So let me search google to see if I can install QT without being a root!So I posted this question on QT news group and got a very quick and early response. They told me that I can use ./configure
./configure -prefix $HOME/qt or ./configure --prefix=/home/arvind/qt-libs
Now when I tried to do that I figured out there is some problem with my office linux server. It is not even compiling a simple .c file. It is fuming with "cc1: No space left on device: error closing /tmp/ccpDlsaM.s" error. Directory name after /tmp is completely random. Meanwhile IT has reinstalled my Cygwin. Looks like I am much closer to have QT run in office environment!
Still trying to run QT ..somehow... Also learning QT.
I had three options to have QT applications working on my office PC.
(1) Install MingW and have it live peacefully with Cygwin, then use MingW to compile QT.
(2) Try to compile QT with just Cygwin.
(3) Login to company linux server, run QT apps there, export the display from there. On Windows PC run Cygwin/X.
I had already exhausted options (1) and (2). I spent a lot of time on that. And while working on (3) I corrupted my existing Cygwin which we need to compile my offical project :). So I logged call for IT ops to reinstall Cygwin. I would also see if they can install Cygwin/X for me. If that happens then I would just have to take care of installing QT in my linux home directory and wow!
Meanwhile I searched google for some other free X-server for windows and I got a link where it was mentioned that there is X-Server called X-Deep which is free. But when I went to their site it was mentioned that Free version is no longer there! I installed 15 days trial period! So now first hurdle is gone at least for next 15 days I can run my xserver and may be even QT applications! Now let me try to install QT in my home directory!
Lets see what happens.
Meanwhile I have also started learning QT. Going through world of Signals, Slots and Widgets. Coming weekend is a big weekend so am hoping that I would at least be able to make some simple programs in QT once this weekend is over! Amen!
Also I am uploading my remaining photos on photos.yahoo.com. Great to see the technology advancement. I am planning to take backup of my entire photos on yahoo photos. So they are kind of permanent.
(1) Install MingW and have it live peacefully with Cygwin, then use MingW to compile QT.
(2) Try to compile QT with just Cygwin.
(3) Login to company linux server, run QT apps there, export the display from there. On Windows PC run Cygwin/X.
I had already exhausted options (1) and (2). I spent a lot of time on that. And while working on (3) I corrupted my existing Cygwin which we need to compile my offical project :). So I logged call for IT ops to reinstall Cygwin. I would also see if they can install Cygwin/X for me. If that happens then I would just have to take care of installing QT in my linux home directory and wow!
Meanwhile I searched google for some other free X-server for windows and I got a link where it was mentioned that there is X-Server called X-Deep which is free. But when I went to their site it was mentioned that Free version is no longer there! I installed 15 days trial period! So now first hurdle is gone at least for next 15 days I can run my xserver and may be even QT applications! Now let me try to install QT in my home directory!
Lets see what happens.
Meanwhile I have also started learning QT. Going through world of Signals, Slots and Widgets. Coming weekend is a big weekend so am hoping that I would at least be able to make some simple programs in QT once this weekend is over! Amen!
Also I am uploading my remaining photos on photos.yahoo.com. Great to see the technology advancement. I am planning to take backup of my entire photos on yahoo photos. So they are kind of permanent.
Wednesday, March 14, 2007
Cleartext property
I was waiting for the IT ops to supply me the new linux server user ID and password, so I started google and searched for ways to export display from Linux machine to windows and I came across a pretty good article which is
10 things you should do to every windows PC ( http://builder.com.com/5100-6404_14-5906772.html )
I especially liked Turn on ClearType and adjust Desktop settings. Here are the things you need to do ....
1. Right-click on the desktop.
2. Go to the Appearance tab.
3. Click the Effects button.
4. Check this option in the Effects dialog box: Use The Following Method To Smooth Edges Of Screen Fonts.
5. Select ClearType from the drop-down box.
6. Click OK.
Above text is taken from http://articles.techrepublic.com.com/5100-22_11-5100472.html
Now I am trying to install Cygwin/X on my Cygwin installation. With this I intentend to export my linux machine to export its display to my Windows PC. And then I would try to run QT applications on my linux server. LEts see how it goes!
OH NO !!!
My previously installed company provided cygwin has gone!! I dont seem to be having a directory named C:\Cygwin!! And when I run any linux command line ls I get the error . Whose text is "The procedure entry point __getreent could not be located in the dynamic link library cygwin1.dll" ... Again one more call to IT.
Looks like I am still a long way before I can install Cygwin/X and run QT apps either on Cygwin or in linux server. Going for break now !!
10 things you should do to every windows PC ( http://builder.com.com/5100-6404_14-5906772.html )
I especially liked Turn on ClearType and adjust Desktop settings. Here are the things you need to do ....
1. Right-click on the desktop.
2. Go to the Appearance tab.
3. Click the Effects button.
4. Check this option in the Effects dialog box: Use The Following Method To Smooth Edges Of Screen Fonts.
5. Select ClearType from the drop-down box.
6. Click OK.
Above text is taken from http://articles.techrepublic.com.com/5100-22_11-5100472.html
Now I am trying to install Cygwin/X on my Cygwin installation. With this I intentend to export my linux machine to export its display to my Windows PC. And then I would try to run QT applications on my linux server. LEts see how it goes!
OH NO !!!
My previously installed company provided cygwin has gone!! I dont seem to be having a directory named C:\Cygwin!! And when I run any linux command line ls I get the error . Whose text is "The procedure entry point __getreent could not be located in the dynamic link library cygwin1.dll" ... Again one more call to IT.
Looks like I am still a long way before I can install Cygwin/X and run QT apps either on Cygwin or in linux server. Going for break now !!
Trying to run QT on linux.
Trying to run QT on linux.
So I gave hope of compiling QT even on Cygwin! But not running QT. Then I remembered that our company has some linux server as well. Now am trying to login to linux server.
Oops I forgot the password as last time I logged into system was two years back ! So I raised trouble ticket with IT. Am waiting for that ! Meanwhile I need to download XFree server so that I can export display on my telnet session to my windows PC so that I can run QT app in telnet session! Hope this works!
So I gave hope of compiling QT even on Cygwin! But not running QT. Then I remembered that our company has some linux server as well. Now am trying to login to linux server.
Oops I forgot the password as last time I logged into system was two years back ! So I raised trouble ticket with IT. Am waiting for that ! Meanwhile I need to download XFree server so that I can export display on my telnet session to my windows PC so that I can run QT app in telnet session! Hope this works!
Trying to compile QT under Cygwin.
Today I am trying to compile QT under CYGWIN. I have successfully installed QT, Eclipse and CDT on my home computer. But in office we have Cygwin so I am trying to compile QT under Cygwin.
So far I am not able to do so. I am getting an error saying ....
In file included from generators/makefiledeps.cpp:30:
../mkspecs/win32-g++/qplatformdefs.h:45:21: windows.h: No such file or directory
Then I opened file qplatformdefs.h and saw that it is able to include many files. like tchar.h. So I did a global search of tchar.h in my C drive to find out where the hell this guy is picking tchar.h from I would put the windows.h in same location. [Of course I did dir /s windows.h in C: to find out there six copies of windows.h in my PC !].. Lets us see where are all the places where I find tchar.h
Meanwhile another idea strcuk. I figured out that mingw32-make was coming from C:\Mingw\bin. I removed its path from path variable. And copied mingw32-make.exe to C:\utils\Cygwin\usr\bin. After that I found out that it started cribbing about tchar.h.
Then I copied windows.h to c:\mingw\include where tchar.h was there and then add c:\ming32\bin back to path. Then it cribbed about lots of other .h file like windef.h etc. etc. I copied them from c:\utils\cygwin\usr\include\mingw to c:\mingw\include then I got following error
C:/MinGW/bin/../lib/gcc/mingw32/3.4.5/../../../../include/stdio.h:432: error: `__gnuc_va_list' has not been declared
C:/MinGW/bin/../lib/gcc/mingw32/3.4.5/../../../../include/stdio.h:433: error: `__gnuc_va_list' has not been declared
C:/MinGW/bin/../lib/gcc/mingw32/3.4.5/../../../../include/stdio.h:434: error: `__gnuc_va_list' has not been declared
C:/MinGW/bin/../lib/gcc/mingw32/3.4.5/../../../../include/stdio.h:435: error: `__gnuc_va_list' has not been declared
C:/MinGW/bin/../lib/gcc/mingw32/3.4.5/../../../../include/stdio.h:467: error: `__gnuc_va_list' has not been declared
C:/MinGW/bin/../lib/gcc/mingw32/3.4.5/../../../../include/stdio.h:469: error: `__gnuc_va_list' has not been declared
C:/MinGW/bin/../lib/gcc/mingw32/3.4.5/../../../../include/stdio.h:471: error: `__gnuc_va_list' has not been declared
C:/MinGW/bin/../lib/gcc/mingw32/3.4.5/../../../../include/stdio.h:473: error: `__gnuc_va_list' has not been declared
and still I am struggling to compile QT under Cygwin !!!
So far I am not able to do so. I am getting an error saying ....
In file included from generators/makefiledeps.cpp:30:
../mkspecs/win32-g++/qplatformdefs.h:45:21: windows.h: No such file or directory
Then I opened file qplatformdefs.h and saw that it is able to include many files. like tchar.h. So I did a global search of tchar.h in my C drive to find out where the hell this guy is picking tchar.h from I would put the windows.h in same location. [Of course I did dir /s windows.h in C: to find out there six copies of windows.h in my PC !].. Lets us see where are all the places where I find tchar.h
Meanwhile another idea strcuk. I figured out that mingw32-make was coming from C:\Mingw\bin. I removed its path from path variable. And copied mingw32-make.exe to C:\utils\Cygwin\usr\bin. After that I found out that it started cribbing about tchar.h.
Then I copied windows.h to c:\mingw\include where tchar.h was there and then add c:\ming32\bin back to path. Then it cribbed about lots of other .h file like windef.h etc. etc. I copied them from c:\utils\cygwin\usr\include\mingw to c:\mingw\include then I got following error
C:/MinGW/bin/../lib/gcc/mingw32/3.4.5/../../../../include/stdio.h:432: error: `__gnuc_va_list' has not been declared
C:/MinGW/bin/../lib/gcc/mingw32/3.4.5/../../../../include/stdio.h:433: error: `__gnuc_va_list' has not been declared
C:/MinGW/bin/../lib/gcc/mingw32/3.4.5/../../../../include/stdio.h:434: error: `__gnuc_va_list' has not been declared
C:/MinGW/bin/../lib/gcc/mingw32/3.4.5/../../../../include/stdio.h:435: error: `__gnuc_va_list' has not been declared
C:/MinGW/bin/../lib/gcc/mingw32/3.4.5/../../../../include/stdio.h:467: error: `__gnuc_va_list' has not been declared
C:/MinGW/bin/../lib/gcc/mingw32/3.4.5/../../../../include/stdio.h:469: error: `__gnuc_va_list' has not been declared
C:/MinGW/bin/../lib/gcc/mingw32/3.4.5/../../../../include/stdio.h:471: error: `__gnuc_va_list' has not been declared
C:/MinGW/bin/../lib/gcc/mingw32/3.4.5/../../../../include/stdio.h:473: error: `__gnuc_va_list' has not been declared
and still I am struggling to compile QT under Cygwin !!!
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