Unsando Qt En C++

T H E U N I V E R S I T Y of T E X A S
HEALTH SCIENCE CENTER AT HOUSTON
S C H O O L of H E A L T H I N F O R M A T I O N S C I E N C E S

Using C++ and Qt in Practice
For students of HI 5323“Image Processing”
Stefan Birmanns, Ph.D.
School of Health Information Sciences
http://biomachina.org/courses/processing/04.html

Outline
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Files (.cpp, .h)Preprocessor, Compiler, Linker
Shared Libraries
Makefiles and Qmake
Qt
Qt Designer
Demo

File Types
• .cpp, .c – Source code files
Definition of your program
int funcA(int i)

Definition

{return 5*i;
}
int funcA(int i);

Declaration

Before using a function/class you need to declare or define it
int i;
extern int i;

Definition
Declaration

Modules
Use multiple .cpp/.c filesto group functions and classes into modules

-

E.g. “fileio.c filter.c display.c”

Code is easier to understand, easier to locate functions, etc.
Compilation time gets reduced

-

Only thechanged module needs to get recompiled
Works only if no dependencies between modules exist
•

If one changes the interface of module A, also the other modules need to
get recompiled

Module Aneeds to know about functions/classes provided by Module B

-

Header files

Every class/function/object can only get defined once!

Definitions
• One time definition rule:
Everyclass/function/object must be defined only once!
File fileio.c
int x;
File filter.c
float x; // error! X already defined
extern int x; // ok, just declaration
extern float x; // error! wrong type
intfuncA() { float x; } // ok, different scope
class clA
{
float x; // also ok, different scope
}

File Types
• .h – Header files
Define a common interface between all modules
Function and classdeclarations

-

int funcA(int i);
class B { B(int i); }

But no definitions!

-

int funcA(int i){ return i*5; }
int global_i;

// not in .h!

// not in .h!

Everything can only...