http://hedgezzz.pixnet.net/blog/post/6527671

這是之前所 po 的 function pointer ,  找到幾個蠻有意思的 webpage , 可以有更多 sample code

可以研究 :

http://alexbowe.com/dry-function-pointers-in-c/

http://denniskubes.com/2013/03/22/basics-of-function-pointers-in-c/

http://harmful.cat-v.org/software/c++/

http://www.dreamincode.net/forums/topic/264061-c11-fun-with-functions/

 

隨意小 sample :

typedef int (*MARS)(int,int) ;

int test1(int i,int  j)
{
    return i + j ;
}
int test2(int i,int  j)
{
    return i * j ;
}

int docalc(MARS f,int i ,int j)
{
    return f(i,j) ;
}

int main()
{
    MARS m1=&test1 ;
    MARS m2=&test2 ;
    int ix1 = docalc(m1,100,20) ;
    int ix2 = docalc(m2,100,20) ;
    printf("(%d)(%d)\n",ix1,ix2) ;
}

 From the following sample , with --std=c++0x

http://www.dreamincode.net/forums/topic/264061-c11-fun-with-functions/ 

int foo(double x)
{
    int iret ;
    iret = (int) x ;
    return x ;
}

int main() {

    //the old
    int (*foo_ptr)(double) = &foo;

    //the new
    std::function<int(double)> call_foo = &foo;

    //auto
    auto call_foo1 = &foo;
    decltype(&foo) call_foo2 = &foo;
    std::function<decltype(foo)> call_foo3 = &foo;


    std::cout << foo(5.0) << std::endl ;
    std::cout << call_foo(15.0) << std::endl ;
    std::cout << call_foo1(25.0) << std::endl ;
    std::cout << call_foo2(35.0) << std::endl ;
    std::cout << call_foo3(45.0) << std::endl ;
}

 

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