Undefined reference to external variable
-
I declared here an extern variable:
open.h
@
extern QString filename;
@
I defined here: open.cpp
@
void open::openfile()
{
QString filename=QFileDialog::getOpenFileName(
0,
QObject::tr("Open File"),
("C://"),
("BITMAP(*.bmp)")
);
QFile file(filename);
file.open(QIODevice::ReadOnly);
QByteArray ba=file.readAll();}@
And i want to use here like this:
mainwindow.cpp
@
ui->lineEdit->setText(filename);
@
But i got this error: undefined refernce to 'filename'
What am i doing wrong? -
Hi,
in your code, filename is a local variable inside your openfile() function. For it to be an extern variable, you need to define it outside all functions:
@
QString filename;void open::openfile()
{
filename = ...
@However, consider redesigning your program. Minimize your use extern/global variables to make your code more maintainable -- make filename a member variable of an object instead.
