Daily C++ notes on STL

C++ notes:  Feb. 24, 2011

We hope to concentrate on OOP and STL today.

Reference: 

Nice one on the <vectors> 

http://www.mochima.com/tutorials/vectors.html

http://www.codeguru.com/cpp/cpp/cpp_mfc/stl/article.php/c4027

The tutorial on STL:  http://www.mochima.com/tutorials/STL.html

http://www.cplusplus.com/reference/stl/vector/vector/

http://www.dreamincode.net/forums/topic/33631-c-vector-tutorial/

=======================

Note that 

class less 
{
   int val;
public:
   less(int v): val(v) {}   // this is to assign val = v to initialize the threshold
};
useage: 
less less_than_five(5);

For references, they often act like a "alias"  -- good new is that when passing the parameter through references, there is not copy of that parameter, such that you don't have to allocate more from the memory. 

For template  -- it acts like the "decoration"

Below is to get the reference of the smaller one:

template<class T> 
T& min(T&a, T&b)
{
   return a<b ? a:b;
}

An example of "vector"

template<class T>

class vector

{

 T* v;

 int sz;

public: 

    vector(int s) {v = new T[sz = s];}

    ~vector() {delet []v; }

    T & operator[] (int i) {return v[i]; }

    int get_size() {return sz;}

}

usage: 

vector<int> int_vector(10);

Some STL- FTP:

1) HP ( Alexander Stepanov and Meng Lee)  ftp://butler.hpl.hp.com/stl/

2) David Mussers   --- http://www.cs.rpi.edu/~musser/stl.html

Some other Resources

STL Tutorial Resources at Addison Wesley

Source Code for the Book's Example Programs

The C++ Standard

Cygwin Tools (Including GNU C++)

[Containers]

set, multiset, map, multimap

Difference between set(multiset) and map(multimap)

set(multiset) --> containd the KEY

map(multimap) --> separate the key and corresponding value

-------------------------------

class employee_data
{
public:
employee_data(): name(""), skill(0); salary(0) {}
employee_data(string n, int s, long sa): name(n), skill(s), salary(sa) {}

string name;
int skill;
long salary;
friend ostream& operater<<(ostream& os, const employee_data& e);
};
ostream& operator<<(ostream& os, const employee_data& e)
{
os<< "employee: " << e.name << " " << e.skill << "" << e.salary;
}
class employee
{
public:
employee(int ii, const employee_data &e): identification_code(ii), description(e){}
int identification_code;
employee_data description;

bool operator<(const employee& e) const
{
return identification_code <e.identification_code;
}
};

if use the set(multiset):

set<employee, less<employee>> employee_set;

multiset<employee, less<employee>> employee_multiset;   // notice that the KEY and values are together, which is employee

if use the map(multimap):

map<int, employee_data, less<int>> employee_map;

multimap<int, employee_data, less<int>> employee_multimap;

when using them:

employee_data ed("john", 1, 500);      // Jone, skill-1, salari(500)

employee e1(1010, ed);                    //  John wiht identification_code as 1010

employee_set.insert(e1);                // to add the information of John

employee_set.insert(e1);               // this won't work

employee_multimap.insert(makepair(101, ed1));             // to add the information of John

employee_multimap.insert(makepair(101, ed2));             // to add the information of another one also with the key as 101

--> so one key --> maps to multiple people

--

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