c 中的回调和 c 中的指针

Question

I have a task to make a function that summarize array and list elements(int type) with callbacks using 2 given signatures:

typedef void (* callback )( void * ctx , int * value );
void arrayForeach ( void * ctx , callback func , int * arr , int n );

I don't know how I can use function pointers here so I have no idea what to do. Can write this simple code for me and explain what is callback, please.

Answer 1

/*  caller must check if arr[0] to arr[n-1] is a valid array or part of an array */
void arrayForEach(int ctx, callback func, int * arr, int n)
{
    for (int i = 0; i < n; i++)
    {
        func(ctx, arr[i]);
        /* you could also use (*func)(ctx, arr[i]); */
    }
}