将收到的参数传递给回调函数 [英] Pass received argument to a callback function

问题描述

我正在用C进行一个Gtk项目.

I am working on a Gtk project in C.

从main.c中，我调用一个以整数地址作为参数的 function1 .

From the main.c I call a function1 with an int address as a parameter.

在该 function1 中，我可以访问该第一个值，但是在该 function1 的末尾(内部)，我调用另一个 function2 (这是click事件的回调函数)，并将我从 function1 参数获得的地址传递给它.

In that function1, I can access that first value, but then at the end (inside) of that function1, I call another function2 (which is a callback function to a click event) and pass it the address I got from the function1 parameter.

但是在 function2 中，地址已更改，绝对无法弄清为什么 ...

But in function2, the address have changed, definitely can't figure out why...

我的项目如下:

[main.c]

int main(...) {

    int a = 50;
    function1(&a);

}

[function1.c]

void function1(int* nb) {
    ...
    g_signal_connect(G_OBJECT(button),"clicked", G_CALLBACK(function2), &nb);
    // I know that the 4th arg expects void*, but even though I give the address of that _nb_ parameter, still can't get that 50 in function2
}

[function2.c]

void function2(void* nb) {
    ...
    printf("should got 50 : %d ", *(int*)nb);
    // shows random 8 digits number like 60035152
}

忘记提及每个函数在单独的文件中，只要我执行包含并给出原型，我就不知道这是否重要...

Forgot to mention that each function is in a separate file, I don't know if that matters as long as I do the includes and gives the prototypes...

提前谢谢...

推荐答案

您的代码中的问题是:-

The problem's in your code are:-

1)您正在将变量的地址传递给回调函数 所以应该是nb，而不是& nb.

1) you are passing the address of the variable to the callback function so instead of &nb, it should be nb.

2)这是点击信号的回调函数( https://developer.gnome.org/gtk3/stable/GtkButton.html#GtkButton-clicked_

2) this is the callback function for clicked signal (https://developer.gnome.org/gtk3/stable/GtkButton.html#GtkButton-clicked_

void
user_function (GtkButton *button,
               gpointer   user_data)

您在回调函数中缺少参数

you are missing an argument in your callback function

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