-bash-2.05b$ cat my.cpp
#include <string>
#include <iostream>
using namespace std;
// just for "#include <hash_map>" in linux
#if __GNUC__>2
#include <ext/hash_map>
using __gnu_cxx::hash_map;
#else
#include <hash_map>
#endif
// 0 define the class
class ClassA{
public:
ClassA(int a):c_a(a){}
int getvalue()const { return c_a;}
void setvalue(int a){c_a = a;}
private:
int c_a;
};
// 1 define the hash function
struct hash_A{
size_t operator()(const class ClassA & A)const{
// return hash<int>(classA.getvalue());
return A.getvalue();
}
};
// 2 define the equal function
struct equal_A{
bool operator()(const class ClassA & a1, const class ClassA & a2)const{
return a1.getvalue() == a2.getvalue();
}
};
int main()
{
hash_map<ClassA, string, hash_A, equal_A> hmap;
ClassA a1(12);
hmap[a1]="I am 12";
ClassA a2(198877);
hmap[a2]="I am 198877";
cout<<hmap[a1]<<endl;
cout<<hmap[a2]<<endl;
return 0;
}
-bash-2.05b$ make my
c++ -O -pipe -march=pentiumpro my.cpp -o my
-bash-2.05b$ ./my
I am 12
I am 198877
在Visual Studio下，hash function 和 equal function 在一个结构中，不想SGI的是分开的。
class MyClass
{
....
};
