Wikipedia:Reference desk/Archives/Computing/2023 November 14

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November 14

Any C++ programmers here? Trying to build GUI like Java's JOptionPane.

I downloaded eclipse, and find out there is no C++ equivalent of Java's JOptionPane without downloading other libraries, such as Qt Creator.

I'm trying code that has

#include <QCoreApplication>
#include <QInputDialog>
#include <QMessageBox>
#include <QFile>
#include <QTextStream>

and get build error:

g++ "-IC:\Qt\6.6.0\mingw_64\include" -O0 -g3 -Wall -c -fmessage-length=0 -o WritingApp.o "..\WritingApp.cpp" ..\WritingApp.cpp:1:10: fatal error: QCoreApplication: No such file or directory 1 | #include <QCoreApplication> | ~~

then tried

#include <QtCore/QCoreApplication>
#include <QtWidgets/QInputDialog>
#include <QtWidgets/QMessageBox>
#include <QtCore/QFile>
#include <QtCore/QTextStream>

and got the build error

g++ "-IC:\Qt\6.6.0\mingw_64\include" -O0 -g3 -Wall -c -fmessage-length=0 -o WritingApp.o "..\WritingApp.cpp" g++ -L-LC:/Qt/6.6.0/mingw_64/lib -mwindows -o WritingApp.exe WritingApp.o -lg++ -o WritingApp.exe WritingApp.o C:/Qt/6.6.0/mingw_64/lib QtWidgets QtGui QtQml QtNetwork QtCore C:\Users\lonel\Downloads\w64devkit-1.20.0\w64devkit\bin/ld.exe: cannot find C:/Qt/6.6.0/mingw_64/lib: Permission denied C:\Users\lonel\Downloads\w64devkit-1.20.0\w64devkit\bin/ld.exe: cannot find QtWidgets: No such file or directory

170.76.231.162 (talk) 17:03, 14 November 2023 (UTC).

It looks like your program isn't properly linked. Did you correctly install Qt? I think g++ didn't find the Qt library files, probably because Eclipse build isn't providing the correct installation directory for the Qt package. Check the Eclipse C++ docs to see in which directories it looks for header files, and make sure the Qt files are in one of those.

Also, you might want to try running Eclipse as administrator, because it says something about permission denied, which might mean g++ doesn't have the necessary permissions to access the header files you included. Good luck! SPA5CE! talk about it 18:28, 14 November 2023 (UTC)

When I right click my project, select Properties > C/C++ Build > Settings > Tool Settings > MinGW C++ Linker > what should I have in the -l and -L fields?

For -l, I have

g++ -o WritingApp.exe WritingApp.o C:/Qt/6.6.0/mingw_64/lib QtWidgets QtGui QtQml QtNetwork QtCore

And for +L, I have

-LC:/Qt/6.6.0/mingw_64/lib 170.76.231.162 (talk) 18:23, 15 November 2023 (UTC).

IP range to subnet tool

Before I start reinventing the wheel, is there a command line tool (preferably open source) that will accept two IP addresses (either as arguments or from stdin I'm not picky there) and produce to stdout one or more IP/mask values that cover the range? e.g. if given say, "127.0.0.0" and "127.0.255.255", will output "127.0.0.0/16". 72.80.78.150 (talk) 23:19, 14 November 2023 (UTC)

ipcalc will do that. I don't know which OS you're using but I think ipcalc runs on both Windows and Linux.

$ ipcalc -d 127.0.0.0-127.0.255.255
[Deaggregated networks]
Network:	127.0.0.0/16

CodeTalker (talk) 00:39, 15 November 2023 (UTC)

Exactly what I was looking for, thanks! 72.80.78.150 (talk) 02:08, 15 November 2023 (UTC)