C language function pointer differences and practical application of the pointer to the function

1. pointer to the function

　　Function is a pointer to return a pointer to the function , is the main function , the return value is a pointer  

　　The basic form of the statement: return data type  + + *  function name  +  (variable type 1, ...) ;

int* fun(int,int);  
int * fun(int,int);
int *fun(int,int);

　　These three statements are, more intuitive first return value is of type int *.

#include <stdio.h>
 int * Fun ( int * X)     // pointer passed   
{
     int * X = tmp;       // pointer tmp point X 
    return tmp;        // return address pointing tmp 
}
 int main () 
{ 
    int = b 2 ;      
     int * p = & b;    // address pointed to by p b of 
    the printf ( " % D " , * Fun (p)); // the value of the output of the address pointed to by p 
    return  0 ; 
}

　　Output: 2

 

2. The function pointer

　　Function pointer is  a pointer to a function of  the body is a pointer  points to the address of a function

　　The basic form of the statement: return data type  +  (* function name)  +  (variable type 1, ...) ;

　　Note * and function names between braces, or because of priority reasons operators becomes a function pointer

int (*fun) (int);

#include <stdio.h>
 int the Add ( int X, int Y) 
{ 
    return X + Y; 
} 
int (Fun *) ( int , int );             // declare function pointer 
int main () 
{ 
    Fun = & the Add;                     // fun add function pointer to a function of 
    the printf ( " % D " , fun ( . 3 , . 5 ));         
    the printf ( " % D " , (* fun) ( . 4 , 2 ));
     return  0;
}

　　输出结果：8 6
　　In the above examples, when the use of function pointers fun(3,5)and (*fun)(3,5)are

 

　　Parameters of the function parameter list function pointer to a pointer to a function and a list of the same

　　Remember that the main function is to return the pointer function pointer and function pointer is a pointer to a function
　　on that basis may have a function pointer and function pointer to a function pointer like
　　a pointer when the function declaration and function names do not need to * brackets
　　function pointer * requires when it was declared and the function name in parentheses (priority of reason)

3. Application of the pointer to the function

 

 

 

4. Application of function pointers