function pointers returned by functions

I'm trying to learn pointers in C++, but seems that it get more complicated...

In the main loop

int i;
for (i = 0; i < 5; ++i){
    if (fun == arrfun[i]) break;
}

How is that fun==arrfun[i] at fun2 if both fun and arrfun start looping form 0? Hence they should equal at log(x) instead. How could I loop to sin or cos, etc?

#include <iostream>
#include <cmath>

using namespace std;

typedef double(*FUNDtoD)(double);
typedef FUNDtoD ARRFUN[];

FUNDtoD funmax(ARRFUN, double);

double fun0(double x) { return log(x); }
double fun1(double x) { return x*x;    }
double fun2(double x) { return exp(x); }
double fun3(double x) { return sin(x); }
double fun4(double x) { return cos(x); }

int main() {

    ARRFUN arrfun = { fun0, fun1, fun2, fun3, fun4 };

    FUNDtoD fun = funmax(arrfun, 1);

    int i;
    for (i = 0; i < 5; ++i){
        if (fun == arrfun[i]) break;
    }

    cout.precision(14);
    cout << "Largest value at x=1 assumed by function # "
        << i << ".\nThe value is " << fun(2) << endl;

    return 0;
}

FUNDtoD funmax(ARRFUN f, double x){
    double m = f[0](x), z;
    int k = 0;

    for (int i = 1; i < 5; i++){
        if ((z = f[i](x)) > m) {
            m = z;
            k = i;

        }
    }
    return f[k];
}

I don't understand how function FUNDtoD funmax is working at the bottom, could somebody clarify it please, many thanks.