i am trying to write a static library & use it...
i have googling a lot & still not solve my prob
please look what i am doing & point where its goes wrong
i will explain detail here:

1. create static library
choose menu
File > New File or Project... > Other Project > C++ Library
click button Choose...
type (library) name: simple
(i uncheck QtCore in required modules for simplicity)
class name "Simple" (by default) and click button Next then Finish
a folder named simple-build-desktop will be created.

click Build and generated file will be
Qt Code: 
  1. + debug
  2.      + simple.o
  3.      + libsimple.a
  4.   + release
  5.   + Makefile
  6.   + Makefile.Debug
  7.   + Makefile.Release
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(this library only keep class Simple with default constructor.. that's all)

2. Using the static library
* create a new project File > new File or Project... >Qt C++ Project > Qt Console Application named UsingLib then click Next > Finish

* copy libsimple.a to project folder (./UsingLib)

* put LIBS += ./libsimple.a or LIBS += -lsimple

* put #include <simple.h> in main.cpp

try to build but it gives error:
simple.h: No such file or directory

i also try to put libsimple.a in c:\ (c:\libsimple.a) & use these combinations:
LIBS += -Lc:/ -lsimple
LIBS += c:/libsimple.a
win32:LIBS += -Lc:/ -lsimple

none of them work