Puntero de función en C

#include <stdio.h>
// A normal function with an int parameter
// and void return type
void fun(int a)
{
    printf("Value of a is %d\n", a);
}
  
int main()
{
    // fun_ptr is a pointer to function fun() 
    void (*fun_ptr)(int) = &fun;
  
    /* The above line is equivalent of following two
       void (*fun_ptr)(int);
       fun_ptr = &fun; 
    */
  
    // Invoking fun() using fun_ptr
    (*fun_ptr)(10);
  
    return 0;
}

#include <stdio.h>
// A normal function with an int parameter
// and void return type
void fun(int a)
{
    printf("Value of a is %d\n", a);
}
  
int main()
{ 
    void (*fun_ptr)(int) = fun;  // & removed
  
    fun_ptr(10);  // * removed
  
    return 0;
}

#include <stdio.h>
void add(int a, int b)
{
    printf("Addition is %d\n", a+b);
}
void subtract(int a, int b)
{
    printf("Subtraction is %d\n", a-b);
}
void multiply(int a, int b)
{
    printf("Multiplication is %d\n", a*b);
}
  
int main()
{
    // fun_ptr_arr is an array of function pointers
    void (*fun_ptr_arr[])(int, int) = {add, subtract, multiply};
    unsigned int ch, a = 15, b = 10;
  
    printf("Enter Choice: 0 for add, 1 for subtract and 2 "
            "for multiply\n");
    scanf("%d", &ch);
  
    if (ch > 2) return 0;
  
    (*fun_ptr_arr[ch])(a, b);
  
    return 0;
}

// A simple C program to show function pointers as parameter
#include <stdio.h>
  
// Two simple functions
void fun1() { printf("Fun1\n"); }
void fun2() { printf("Fun2\n"); }
  
// A function that receives a simple function
// as parameter and calls the function
void wrapper(void (*fun)())
{
    fun();
}
  
int main()
{
    wrapper(fun1);
    wrapper(fun2);
    return 0;
}

// An example for qsort and comparator
#include <stdio.h>
#include <stdlib.h>
  
// A sample comparator function that is used
// for sorting an integer array in ascending order.
// To sort any array for any other data type and/or
// criteria, all we need to do is write more compare
// functions.  And we can use the same qsort()
int compare (const void * a, const void * b)
{
  return ( *(int*)a - *(int*)b );
}
  
int main ()
{
  int arr[] = {10, 5, 15, 12, 90, 80};
  int n = sizeof(arr)/sizeof(arr[0]), i;
  
  qsort (arr, n, sizeof(int), compare);
  
  for (i=0; i<n; i++)
     printf ("%d ", arr[i]);
  return 0;
}

#include <stdio.h>
#include <stdbool.h>
  
// A compare function that is used for searching an integer
// array
bool compare (const void * a, const void * b)
{
  return ( *(int*)a == *(int*)b );
}
  
// General purpose search() function that can be used
// for searching an element *x in an array arr[] of
// arr_size. Note that void pointers are used so that
// the function can be called by passing a pointer of
// any type.  ele_size is size of an array element
int search(void *arr, int arr_size, int ele_size, void *x,
           bool compare (const void * , const void *))
{
    // Since char takes one byte, we can use char pointer
    // for any type/ To get pointer arithmetic correct,
    // we need to multiply index with size of an array
    // element ele_size
    char *ptr = (char *)arr;
  
    int i;
    for (i=0; i<arr_size; i++)
        if (compare(ptr + i*ele_size, x))
           return i;
  
    // If element not found
    return -1;
}
  
int main()
{
    int arr[] = {2, 5, 7, 90, 70};
    int n = sizeof(arr)/sizeof(arr[0]);
    int x = 7;
    printf ("Returned index is %d ", search(arr, n,
                               sizeof(int), &x, compare));
    return 0;
}