I'm trying to compile the following short C++ program (not written by me) in Debian:

```
$ cat checksig.cpp
#include <QByteArray>
#include <QDebug>

#include <openssl/ec.h>
#include <openssl/evp.h>
#include <openssl/ecdsa.h>
#include <openssl/sha.h>

static EC_KEY* EC_KEY_pub_key ( const QByteArray& pub )
{
  static EC_KEY* eckey = EC_KEY_new_by_curve_name ( NID_secp256k1 );
  const quint8* ppub = (const quint8*)pub.constData ( );
  o2i_ECPublicKey ( &eckey, &ppub, pub.size ( ) );
  return eckey;
}
//--------------------------------------------------------------
int main(int argc, char *argv[])
{
  const QByteArray data ( QByteArray::fromHex ( argv [1] ) );
  const QByteArray sign ( QByteArray::fromHex ( argv [2] ) );
  const QByteArray pubk ( QByteArray::fromHex ( argv [3] ) );

  quint8 tmp [32];
  ::SHA256 ( (const quint8*)data.constData ( ), data.size ( ), tmp );
  quint8 digest [32];
  ::SHA256 ( tmp, 32, digest );
  qDebug ( ) << "data=" << QString ( data.toHex ( ) );
  qDebug ( ) << "sign=" << QString ( sign.toHex ( ) );
  qDebug ( ) << "pubk=" << QString ( pubk.toHex ( ) );

  qDebug ( ) << "digest=" << QString ( QByteArray ( (const char*)digest, 32 ).toHex ( ) );

  const bool v ( ::ECDSA_verify ( 0, digest, 32, (const quint8*)sign.constData ( ), sign.size ( ), EC_KEY_pub_key ( pubk ) ) );
  qDebug ( ) << "result=" << v;

  return 0;
}

```

But I don't think I'm using the right includes, or maybe I need to install more Qt libraries?

```
$ g++ -Wall checksig.cpp -o checksig -L /usr/include/i386-linux-gnu/qt5/QtCore/ -lQtCore -I /usr/include/i386-linux-gnu/qt5/QtCore/
In file included from /usr/include/i386-linux-gnu/qt5/QtCore/QByteArray:1:0,
from checksig.cpp:4:/usr/include/i386-linux-gnu/qt5/QtCore/qbytearray.h:45:30: fatal error: QtCore/qrefcount.h: No such file or directory
#include <QtCore/qrefcount.h>
                             ^

```

and alternatively, using includes and libraries from one directory back:

```
g++ -Wall checksig.cpp -o checksig -L /usr/include/i386-linux-gnu/qt5/ -lQtCore -I /usr/include/i386-linux-gnu/qt5/
checksig.cpp:4:22: fatal error: QByteArray: No such file or directory
#include <QByteArray>
                      ^
compilation terminated.

```

I'm new to C++. How can I compile this small program in a 1-liner?

---

As requested in the comments:

```
$ sudo apt-file search "QtCore/qrefcount.h"
qtbase5-dev: /usr/include/i386-linux-gnu/qt5/QtCore/qrefcount.h

```

---

thanks to [Michael Popovich](https://stackoverflow.com/users/4762451/michael-popovich)'s answer i tried the following and got further. but now i have new errors:

```
$ g++ -Wall checksig.cpp -o checksig -L /usr/include/i386-linux-gnu/qt5/QtCore/ -lQtCore -I /usr/include/i386-linux-gnu/qt5/ -I /usr/include/i386-linux-gnu/qt5/QtCore/
In file included from /usr/include/i386-linux-gnu/qt5/QtCore/qatomic.h:42:0,
                 from /usr/include/i386-linux-gnu/qt5/QtCore/qrefcount.h:45,
                 from /usr/include/i386-linux-gnu/qt5/QtCore/qbytearray.h:45,
                 from /usr/include/i386-linux-gnu/qt5/QtCore/QByteArray:1,
                 from checksig.cpp:4:
/usr/include/i386-linux-gnu/qt5/QtCore/qglobal.h:1034:4: error: #error "You must build your code with position independent code if Qt was built with -reduce-relocations. " "Compile your code with -fPIC or -fPIE."
 #  error "You must build your code with position independent code if Qt was built with -reduce-relocations. "\
    ^

```

i have no idea if qt was built with `-reduce-relocations` i don't think i even installed it myself - it was probably pulled in as a dependency for another install.

anyway, trying with `-fPIC` and `-fPIE`:

```
$ g++ -Wall checksig.cpp -o checksig -L /usr/include/i386-linux-gnu/qt5/QtCore/ -lQtCore -I /usr/include/i386-linux-gnu/qt5/ -I /usr/include/i386-linux-gnu/qt5/QtCore/ -fPIC
/usr/bin/ld: cannot find -lQtCore
collect2: error: ld returned 1 exit status
$ g++ -Wall checksig.cpp -o checksig -L /usr/include/i386-linux-gnu/qt5/QtCore/ -lQtCore -I /usr/include/i386-linux-gnu/qt5/ -I /usr/include/i386-linux-gnu/qt5/QtCore/ -fPIE
/usr/bin/ld: cannot find -lQtCore
collect2: error: ld returned 1 exit status

```