Loading library with QLibrary

Question

I found the following code for loading libraries in Qt but I do not fully understand how it works. Could someone explain to me from: typedef int (*MyPrototype)(int, int);?

int r1 = 0;
QLibrary library("mathlib.so");
    if (!library.load())
        out << library.errorString() << endl;
    if (library.load())
        out << "library loaded" << endl;

    typedef int (*MyPrototype)(int, int);

    MyPrototype myFunction = (MyPrototype)library.resolve("add");
    if (myFunction)
        r1 = myFunction(a,b);
    else
        out << library.errorString() << endl;

So I would have to do this for every function I want to call? — Omari Celestine, Jul 15 '17 at 16:24
So my only other option will be to have all the header files available when using the library in an aplication? — Omari Celestine, Jul 15 '17 at 17:02

score 2 · Accepted Answer · answered Jul 16 '17 at 16:21

2

so or dll has function and we want to use it, so how we can call it

int add(int in_iParam1, int in_iParam2)

define function type

typedef int (*MyPrototype)(int, int);

looking for function 'add' in so file

MyPrototype myFunction = (MyPrototype)library.resolve("add");

Call function 'add' with parameters 'a' and 'b' and get result to 'r1'

r1 = myFunction(a,b);

answered Jul 16 '17 at 16:21

Ildar Gumirov

36
3

An does the definition of the Prototype represent anything specific? – Omari Celestine Jul 16 '17 at 17:26
It should contain same types as in function what you will call – Ildar Gumirov Jul 16 '17 at 18:47
OK, But I was referring to the actual name given to the definition of the function: MyPrototype? – Omari Celestine Jul 16 '17 at 19:43
Yes, in function type definition you can use any name – Ildar Gumirov Jul 16 '17 at 21:52

Loading library with QLibrary

1 Answers1