Function pointers and function pointers

1. The function pointer (important):

　　Definition: It is a pointer to the function; i.e. it is a form of the function pointer variable .

　　Format: Return Value Type (* variable name ) (Parameter Type 1, Type 2 ...... parameters);

　　example:

#include<stdio.h>

// define the function function_1 
void function_1 ( int , float )
{
    printf("%s\n", "function_1");
    rreturn 0;
    
}

// define the function function_2 
void function_2 ( int , float )
{
    printf("%s\n","function_2");
    return 0;
    
}

// definition of function pointers pf

int (* pf)(int ,float);

// main function 
int main ()
{
    PF = function_1; // function pointer to function_1 
    PF ( 10 , 3.14 );     // call the function function_1 
    
    PF = function_2; // function pointer to a function_2 
    PF ( 2 , 2.12 );     // call the function function_2
    
    return 0;
    
}

　　Detailed: As described above, the function pointer is a special variable that points to a function. The general format of variable definitions: type variable name ; that is, for it is only normal before the variable name with a type on it.

But for the function pointer is on the complex, the need to add return type (* ) (Parameter Type 1, Type 2 parameters ......); can. I.e., return type (* ) (Parameter Type 1, Type 2 parameters ......); is a type of the function pointer variable.

2. pointer to the function:

　　Definition: It is a function of the type of the return value is a pointer.

　　 Format: Return Value Type * function name (parameter type 1, type 2 parameter)

　　_type_ * function (int, int) with the normal function int function (int, int) Similarly, the data type is simply returned just not the same, _type_ * function (int, int) returns a pointer address, int function (int, int) It returns an int.

#include "stdio.h"
#include "stdlib.h"

int sum =0;
int *getAdd(int a, int b)
{
    sum = a+b;
    return &sum;
}

int getDiff(int a, int b)
{
    return a>b?(a-b):(b-a);
}

int main ()
{
    int *pTemp, Temp;
    pTemp = getAdd(115,10);
    printf("ADD result:%d\n", *pTemp);
    
    Temp = getDiff(115,10);
    printf("DIFF result:%d\n", Temp);
    return 0;
}

Function pointers and function pointers

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