解释一个中期C的例子

//What does this program print?

#include <iostream>
using namespace std;

#define foo1( a )  a * a

int j = 6;

inline  int
foo2( int a ) 
{
    return a * a;
}

void
goo1( int& x )
{
    x = 3;
}

void
goo2( int  x )
{
    x = 3;
}

int main()
{
    int i,j = 12;

    cout << "foo1 = " << foo1( 3 + 2 ) << "n";
    cout << "foo2 = " << foo2( 3 + 2 ) << "n";

    i = 5;
    goo1( i );
    cout << "goo1 = " << i << "n";
    i = 5;
    goo2( i );
    cout << "goo2 = " << i << "n";

    cout << "  j = " <<   j << "n";
    cout << "::j = " << ::j << "n";
}

有人可以解释一下foo1 = 11.我一直在尝试不同的数字一小时,我无法确切地知道如何计算.