# Understanding c++ code **URL:** \ **Category:** GNU Radio\ **Created:** [April 12, 2014, 4:29pm UTC](https://www.ruby-forum.com/t/understanding-c-code/240409 "2014-04-12T16:29:57Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![musicdenotation](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ea666f/32.png) [@musicdenotation](https://www.ruby-forum.com/u/musicdenotation)\ **Post date:** [April 12, 2014, 4:29pm UTC](https://www.ruby-forum.com/t/understanding-c-code/240409/1 "2014-04-12T16:29:57Z")
I installed GNU RADIO from this link [http://blogs.bu.edu/mhirsch/2012/07/installing-gnu-radio-in-ubuntu-12-04-x64/comment-page-1/](http://blogs.bu.edu/mhirsch/2012/07/installing-gnu-radio-in-ubuntu-12-04-x64/comment-page-1/) I want to test some blocks & see their output to understand them more and more. for example I opened additive\_scrambler\_bb c++ codes in terminal to understand but I want to see how some parameters change in code when running it . how to output these parameters in terminal ? Can I write in code “cout” like any c++code? And do I have to build gnuradio again even if I will erase all my modifications in code (I don’t want these modifications permanently I want only to output all parameters to understand the block) I did the following: editing it using vim ./additive\_scrambler\_bb\_impl.cc running it to see the output on terminal using ./additive\_scrambler\_bb\_impl.cc but when I ran it in terminal I got this message: bash: ./additive\_scrambler\_bb\_impl.cc: Permission denied Thanks ---
**Author:** ![Sara\_ChSSrif](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/7ba0ec/32.png) [@Sara\_ChSSrif](https://www.ruby-forum.com/u/Sara_ChSSrif)\ **Post date:** [April 12, 2014, 5:18pm UTC](https://www.ruby-forum.com/t/understanding-c-code/240409/2 "2014-04-12T17:18:20Z")
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi Sara, C++ is a compiled language; you can not execute a source code file. You have to recompile the file by rebuilding GNU Radio. additive\_scrambler\_bb\_impl.cc contains the implementation of the additive\_scrambler\_bb block, it is not itself executable. You need to have a flowgraph containing that block to test your modified version. I think you should start with a basic C++ tutorial before you try to understand and modify GNU Radio’s C++ codebase – these are very basic concepts you are missing. Greetings, Marcus On 12.04.2014 16:18, Sara C. wrote: > I installed GNU RADIO from this link [http://blogs.bu.edu/mhirsch/2012/07/installing-gnu-radio-in-ubuntu-12-04-x64/comment-page-1/](http://blogs.bu.edu/mhirsch/2012/07/installing-gnu-radio-in-ubuntu-12-04-x64/comment-page-1/) > I want to test some blocks & see their output to understand them more and > terminal using ./additive\_scrambler\_bb\_impl.cc > [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 Comment: Using GnuPG with Thunderbird - [http://www.enigmail.net/](http://www.enigmail.net/) iQEcBAEBAgAGBQJTSVj7AAoJEBQ6EdjyzlHtlbIH/2x5VnHdYtdVwcVyo6eOQXwd G56c6M94Hv0IjCaGLegIBIzXvahSzU9Iy6YEg4SyY0OHMgvVMQOqILVIoEqpT6XW mo+iQRUNTeIvHth2jdH+mhV3S4F50+VJNJ6N7vTqwLIBbneutOlCh1ltUbCTXnCc P2BuwctfZssutb1AeYyTFQ1/pOimpIBVicrKrVh8Fe7H+6NEiP4c3YljRWJtbU+T td5qG4WJVsxU3+tpP4PaxZ15x3KS8dfqYAQUL5UzmrpRaob1GbIgkNYtdVgER/6y Pi3YeFwStPFnBzTO+X/wzr9YjC/wRqXF4bA2ZwKsTs/ws6nXfXPXsFo5V/iSeFs= =GESY -----END PGP SIGNATURE----- ---
**Author:** ![Sara\_ChSSrif](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/7ba0ec/32.png) [@Sara\_ChSSrif](https://www.ruby-forum.com/u/Sara_ChSSrif)\ **Post date:** [April 13, 2014, 12:56am UTC](https://www.ruby-forum.com/t/understanding-c-code/240409/3 "2014-04-13T00:56:41Z")
How to rebuild gnuradio after I changed in c++ codes ? Note: I installed GNU RADIO from this link [http://blogs.bu.edu/mhirsch/2012/07/installing-gnu-radio-in-ubuntu-12-04-x64/comment-page-1/](http://blogs.bu.edu/mhirsch/2012/07/installing-gnu-radio-in-ubuntu-12-04-x64/comment-page-1/) 2014-04-12 17:17 GMT+02:00 Marcus M. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): ---
**Author:** ![Sara\_ChSSrif](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/7ba0ec/32.png) [@Sara\_ChSSrif](https://www.ruby-forum.com/u/Sara_ChSSrif)\ **Post date:** [April 13, 2014, 1:03am UTC](https://www.ruby-forum.com/t/understanding-c-code/240409/4 "2014-04-13T01:03:11Z")
how I can re-build digital library only after making changes in c++ code of a block… not re-building the whole gnuradio I installed GNU RADIO from this link [http://blogs.bu.edu/mhirsch/2012/07/installing-gnu-radio-in-ubuntu-12-04-x64/comment-page-1/](http://blogs.bu.edu/mhirsch/2012/07/installing-gnu-radio-in-ubuntu-12-04-x64/comment-page-1/) 2014-04-13 0:55 GMT+02:00 Sara C. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): ---
**Author:** ![Sara\_ChSSrif](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/7ba0ec/32.png) [@Sara\_ChSSrif](https://www.ruby-forum.com/u/Sara_ChSSrif)\ **Post date:** [April 13, 2014, 8:29am UTC](https://www.ruby-forum.com/t/understanding-c-code/240409/5 "2014-04-13T08:29:26Z")
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi Sara, You have to have a full source tree lying around, where you modify the code. Then you follow the official wiki’s guide on how to build from source: [http://gnuradio.org/redmine/projects/gnuradio/wiki/BuildGuide](http://gnuradio.org/redmine/projects/gnuradio/wiki/BuildGuide) Greetings, Marcus PS: I’ve mentioned that already, but let me say this once again: [gnuradio.org](http://gnuradio.org) is the only source of information that’s not likely to outdate. On 13.04.2014 01:02, Sara C. wrote: > > How to rebuild gnuradio after I changed in c++ codes ? Note: I > > installed GNU RADIO from this link [http://blogs.bu.edu/mhirsch/2012/07/installing-gnu-radio-in-ubuntu-12-04-x64/comment-page-1/](http://blogs.bu.edu/mhirsch/2012/07/installing-gnu-radio-in-ubuntu-12-04-x64/comment-page-1/) > > 2014-04-12 17:17 GMT+02:00 Marcus M. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): > > > You need to have a flowgraph containing that block to test > > > > > > > [http://blogs.bu.edu/mhirsch/2012/07/installing-gnu-radio-in-ubuntu-12-04-x64/comment-page-1/](http://blogs.bu.edu/mhirsch/2012/07/installing-gnu-radio-in-ubuntu-12-04-x64/comment-page-1/) > > > > I want to test some blocks & see their output to understand them more and > > > > ./additive\_scrambler\_bb\_impl.cc running it to see the output > > > > on terminal using ./additive\_scrambler\_bb\_impl.cc > > > > > > > > but when I ran it in terminal I got this message: bash: > > > > ./additive\_scrambler\_bb\_impl.cc: Permission denied > > > > > > > > Thanks > > > > -----BEGIN PGP SIGNATURE----- > > > > Version: GnuPG v1 > > > > Comment: Using GnuPG with Thunderbird - [http://www.enigmail.net/](http://www.enigmail.net/) iQEcBAEBAgAGBQJTSi5zAAoJEBQ6EdjyzlHtF3cH/RiYAcNGstQDkd75sPGn/5Ow f7fKpkMZwxvp3rcbtTTda5DPiwEtvxO1yfajiuyRt3/Ono4qDPhoqcCVdY15HlnM NvM1LwjbMXHGH0XQJKa+0ICOW3mCzf2L6Z+1BemyF+tlk3cVX2QwD3aGPN9i8BQ4 7R/BsDCI08wQ1OhGXM1CSJW5MpTyKsrbgjnZAV6+CvLvbSl3Bp2lBkiZvYmvYqJH lWNGfGaC3LvrIOWL9v0Mov2zl1WVXBxqGZzbhJ5v2GExMBj9vdAr7s/TZCliV7/a n0LPjEu2cf5rwI9PQeqqrx1NRZkmf7AFOAv2P+n6CJRC74mijNAlbQkg69luzTo= =BJuE -----END PGP SIGNATURE-----