Step 7 gcc compiler doesnt exist about ev3dev-lang-cpp

[ddemidov]

did you do sudo apt-get update beforehand? It should download the available package lists.

[flemmii]

Yes, this was the result:

Ign:1 http://security.debian.org stretch/updates InRelease
Ign:2 http://httpredir.debian.org/debian stretch InRelease
Ign:3 http://security.debian.org unstable/updates InRelease
Get:4 http://httpredir.debian.org/debian unstable InRelease [191 kB]
Err:5 http://security.debian.org stretch/updates Release
404 Not Found
Ign:6 http://security.debian.org unstable/updates Release
Ign:7 http://security.debian.org unstable/updates/non-free armel Packages
Ign:8 http://security.debian.org unstable/updates/contrib all Packages
Ign:9 http://security.debian.org unstable/updates/non-free all Packages
Ign:10 http://security.debian.org unstable/updates/contrib armel Packages
Ign:11 http://security.debian.org unstable/updates/main all Packages
Ign:12 http://security.debian.org unstable/updates/main armel Packages
Ign:7 http://security.debian.org unstable/updates/non-free armel Packages
Ign:8 http://security.debian.org unstable/updates/contrib all Packages
Ign:9 http://security.debian.org unstable/updates/non-free all Packages
Ign:10 http://security.debian.org unstable/updates/contrib armel Packages
Hit:13 http://archive.ev3dev.org/debian stretch InRelease
Ign:11 http://security.debian.org unstable/updates/main all Packages
Ign:12 http://security.debian.org unstable/updates/main armel Packages
Ign:7 http://security.debian.org unstable/updates/non-free armel Packages
Ign:8 http://security.debian.org unstable/updates/contrib all Packages
Ign:9 http://security.debian.org unstable/updates/non-free all Packages
Ign:14 http://archive.ev3dev.org/debian unstable InRelease
Ign:15 http://httpredir.debian.org/debian stretch Release
Ign:10 http://security.debian.org unstable/updates/contrib armel Packages
Ign:11 http://security.debian.org unstable/updates/main all Packages
Ign:12 http://security.debian.org unstable/updates/main armel Packages
Ign:16 http://httpredir.debian.org/debian stretch/main all Packages
Ign:7 http://security.debian.org unstable/updates/non-free armel Packages
Ign:8 http://security.debian.org unstable/updates/contrib all Packages
Ign:17 http://archive.ev3dev.org/debian unstable Release
Ign:9 http://security.debian.org unstable/updates/non-free all Packages
Ign:18 http://httpredir.debian.org/debian stretch/non-free all Packages
Ign:10 http://security.debian.org unstable/updates/contrib armel Packages
Ign:11 http://security.debian.org unstable/updates/main all Packages
Ign:19 http://httpredir.debian.org/debian stretch/contrib all Packages
Ign:12 http://security.debian.org unstable/updates/main armel Packages
Ign:7 http://security.debian.org unstable/updates/non-free armel Packages
Ign:20 http://httpredir.debian.org/debian stretch/non-free armel Packages
Ign:8 http://security.debian.org unstable/updates/contrib all Packages
Ign:9 http://security.debian.org unstable/updates/non-free all Packages
Ign:21 http://archive.ev3dev.org/debian unstable/main all Packages
Ign:22 http://httpredir.debian.org/debian stretch/main armel Packages
Ign:10 http://security.debian.org unstable/updates/contrib armel Packages
Ign:11 http://security.debian.org unstable/updates/main all Packages
Ign:12 http://security.debian.org unstable/updates/main armel Packages
Ign:23 http://httpredir.debian.org/debian stretch/contrib armel Packages
Err:7 http://security.debian.org unstable/updates/non-free armel Packages
404 Not Found
Ign:8 http://security.debian.org unstable/updates/contrib all Packages
Ign:16 http://httpredir.debian.org/debian stretch/main all Packages
Ign:9 http://security.debian.org unstable/updates/non-free all Packages
Ign:18 http://httpredir.debian.org/debian stretch/non-free all Packages
Ign:19 http://httpredir.debian.org/debian stretch/contrib all Packages
Ign:10 http://security.debian.org unstable/updates/contrib armel Packages
Ign:11 http://security.debian.org unstable/updates/main all Packages
Ign:24 http://archive.ev3dev.org/debian unstable/main armel Packages
Ign:20 http://httpredir.debian.org/debian stretch/non-free armel Packages
Ign:12 http://security.debian.org unstable/updates/main armel Packages
Ign:22 http://httpredir.debian.org/debian stretch/main armel Packages
Ign:23 http://httpredir.debian.org/debian stretch/contrib armel Packages
Ign:16 http://httpredir.debian.org/debian stretch/main all Packages
Ign:18 http://httpredir.debian.org/debian stretch/non-free all Packages
Ign:21 http://archive.ev3dev.org/debian unstable/main all Packages
Ign:19 http://httpredir.debian.org/debian stretch/contrib all Packages
Ign:20 http://httpredir.debian.org/debian stretch/non-free armel Packages
Ign:22 http://httpredir.debian.org/debian stretch/main armel Packages
Ign:24 http://archive.ev3dev.org/debian unstable/main armel Packages
Ign:23 http://httpredir.debian.org/debian stretch/contrib armel Packages
Ign:16 http://httpredir.debian.org/debian stretch/main all Packages
Ign:18 http://httpredir.debian.org/debian stretch/non-free all Packages
Ign:19 http://httpredir.debian.org/debian stretch/contrib all Packages
Ign:21 http://archive.ev3dev.org/debian unstable/main all Packages
Ign:20 http://httpredir.debian.org/debian stretch/non-free armel Packages
Ign:22 http://httpredir.debian.org/debian stretch/main armel Packages
Ign:23 http://httpredir.debian.org/debian stretch/contrib armel Packages
Ign:24 http://archive.ev3dev.org/debian unstable/main armel Packages
Ign:16 http://httpredir.debian.org/debian stretch/main all Packages
Ign:18 http://httpredir.debian.org/debian stretch/non-free all Packages
Ign:19 http://httpredir.debian.org/debian stretch/contrib all Packages
Ign:21 http://archive.ev3dev.org/debian unstable/main all Packages
Ign:20 http://httpredir.debian.org/debian stretch/non-free armel Packages
Ign:22 http://httpredir.debian.org/debian stretch/main armel Packages
Ign:23 http://httpredir.debian.org/debian stretch/contrib armel Packages
Ign:16 http://httpredir.debian.org/debian stretch/main all Packages
Ign:24 http://archive.ev3dev.org/debian unstable/main armel Packages
Ign:18 http://httpredir.debian.org/debian stretch/non-free all Packages
Ign:19 http://httpredir.debian.org/debian stretch/contrib all Packages
Err:20 http://httpredir.debian.org/debian stretch/non-free armel Packages
404 Not Found
Ign:21 http://archive.ev3dev.org/debian unstable/main all Packages
Ign:22 http://httpredir.debian.org/debian stretch/main armel Packages
Ign:23 http://httpredir.debian.org/debian stretch/contrib armel Packages
Ign:24 http://archive.ev3dev.org/debian unstable/main armel Packages
Ign:21 http://archive.ev3dev.org/debian unstable/main all Packages
Err:24 http://archive.ev3dev.org/debian unstable/main armel Packages
404 Not Found
Get:25 http://httpredir.debian.org/debian unstable/main armel Packages [8997 kB]
Get:26 http://httpredir.debian.org/debian unstable/non-free armel Packages [56.7 kB]
Reading package lists... Done
E: The repository 'http://security.debian.org stretch/updates Release' does no longer have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: The repository 'http://security.debian.org unstable/updates Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: The repository 'http://httpredir.debian.org/debian stretch Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: The repository 'http://archive.ev3dev.org/debian unstable Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.

[ddemidov]

Looks like the recommended way to cross-compile now is to use docker:

ev3dev/ev3dev#1562
https://www.ev3dev.org/docs/tutorials/using-docker-to-cross-compile/

[flemmii]

Ok, thank you

[flemmii]

#include
#include
#include

#include "../Headers/ev3dev.h"

using namespace std;
using namespace ev3dev;

int main() {
cout << "Hello, World!" << endl;
while (!button::enter.pressed ());
return 0;
}

Now I want to compile this code, but I get this error:

/tmp/ccVUrwnY.o: In function main': hello.cpp:(.text+0x50): undefined reference to ev3dev::button::pressed() const'
hello.cpp:(.text+0x90): undefined reference to `ev3dev::button::enter'
collect2: error: ld returned 1 exit status

[ddemidov]

You need to link it with the ev3dev.o, which you can get by compiling ev3dev.cpp. Or just pass both hello.cpp and ev3dev.cpp to the compiler.

[flemmii]

If I try to compile ev3dev.cpp I get this error:
/usr/lib/gcc-cross/arm-linux-gnueabi/6/../../../../arm-linux-gnueabi/lib/Scrt1.o: In function _start': (.text+0x54): undefined reference to main'
collect2: error: ld returned 1 exit status

Also some source files can't be opened, like linux/fb.h

Just to let you know, this is my compile command:
docker run --rm -it -v C:\Users\Florian\Documents\WRO\C++\wro:/src -w /src ev3cc arm-linux-gnueabi-g++ -o Build/ev3dev Sources/ev3dev.cpp

[ddemidov]

You need to either compile and link both at once:

g++ -o hello hello.cpp ev3dev.cpp

or compile the cpp files into object files and then link those:

g++ -c -o ev3dev.o ev3dev.cpp
g++ -c -o hello.o hello.cpp
g++ -o hello hello.o ev3dev.o

[flemmii]

Thank you very much, it works with both methods one last question what's faster the first or the second method?

[ddemidov]

I don't think there is any difference, the compiler does the same steps in both cases.

…

-- Cheers, Denis

[ddemidov]

On the second thought, if you use a build system (makefile or cmake), then the second method would be faster, since ev3dev only needs to be compiled once.

[flemmii]

Thank you very much for your time and help :)