в 14:21, 25 мая 2010

2010-05-25T14:21:06Z

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2010-05-25T10:25:52Z

1 версия: Импорт контента...

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==Add user-defined object to map, loop through the map and output==

<source lang="cpp">
#include <algorithm>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <string>
#include <utility>
#include <vector>
using namespace std;
class PC{
public:
enum PC_type { Dell, HP, IBM, Compaq };
PC( PC_type appliance = Dell, int model = 220,
int serial = 0 );
bool operator<( const PC& rhs ) const;
PC_type appliance() const;
int model() const;
string name() const;
void print() const;
int serial() const;
private:
PC_type appliance_;
int model_;
int serial_;
};
inline
PC::PC( PC::PC_type appliance, int model,
int serial )
: appliance_( appliance ), model_( model ), serial_( serial )
{}
inline
bool PC::operator<( const PC& rhs ) const
{ return appliance() < rhs.appliance() ||
( appliance() == rhs.appliance() && model() < rhs.model() );
}
inline
PC::PC_type PC::appliance() const
{ return appliance_; }
inline
int PC::model() const
{ return model_; }
string PC::name() const
{
string what;
switch( appliance() )
{
case Dell: what = "Dell"; break;
case HP: what = "HP"; break;
case IBM: what = "IBM"; break;
case Compaq: what = "Compaq"; break;
default: what = "Unknown appliance"; break;
}
return what;
}
inline
void PC::print() const
{
char oldfill = cout.fill();
cout << name() << " - Model "
<< model() << ", Serial number "
<< serial() << endl;
}
inline
int PC::serial() const
{ return serial_; }
bool greater_model( const pair<PC::PC_type,PC> p,int min_model );
int main( )
{
const PC::PC_type kind[] = { PC::IBM,PC::Dell,PC::HP};
int num_appliances = 3;
vector<PC> v;
for( int i = 0; i < 3; ++i )
v.push_back( PC( kind[i], i, i ) );
map<int,PC> sold;
transform( kind, kind+num_appliances, v.begin(),inserter( sold, sold.end() ),make_pair<int,PC> );
map<int,PC>::const_iterator sold_end = sold.end();
map<int,PC>::const_iterator site;
for( site = sold.begin(); site != sold_end; ++site )
site->second.print();
}

</source>

==Computing an inner product of tuples represented as maps==

<source lang="cpp">

#include <map>
#include <iostream>
using namespace std;
int main()
{
const long N = 600000; // Length of tuples x and y
const long S = 10; // Sparseness factor
map<long, double> x, y;
for (long k = 0; 3 * k * S < N; ++k)
x[3 * k * S] = 1.0;
for (long k = 0; 5 * k * S < N; ++k)
y[5 * k * S] = 1.0;
double sum;
map<long, double>::iterator ix, iy;
for (sum = 0.0, ix = x.begin(); ix != x.end(); ++ix) {
long i = ix->first;
iy = y.find(i);
if (iy != y.end())
sum += ix->second * iy->second;
}
cout << sum << endl;
return 0;
}
/*
4000
*/

</source>

==Create string float map==

<source lang="cpp">

/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <map>
#include <string>
using namespace std;
int main()
{
/* type of the container:
* - map: elements key/value pairs
* - string: keys have type string
* - float: values have type float
*/
typedef map<string,float> StringFloatMap;
StringFloatMap coll;
// insert some elements into the collection
coll["VAT"] = 0.15;
coll["Pi"] = 3.1415;
coll["an arbitrary number"] = 4983.223;
coll["Null"] = 0;
/* print all elements
* - iterate over all elements
* - element member first is the key
* - element member second is the value
*/
StringFloatMap::iterator pos;
for (pos = coll.begin(); pos != coll.end(); ++pos) {
cout << "key: \"" << pos->first << "\" "
<< "value: " << pos->second << endl;
}
}
/*
key: "Null" value: 0
key: "Pi" value: 3.1415
key: "VAT" value: 0.15
key: "an arbitrary number" value: 4983.22
*/

</source>

==Declare a char int map==

<source lang="cpp">

#include <iostream>
#include <map>
using namespace std;
int main()
{
map<char, int> m;
// put pairs into map
for(int i=0; i<26; i++) {
m.insert(pair<char, int>("A"+i, 65+i));
}
char ch = "G";
map<char, int>::iterator p;

// find value given key
p = m.find(ch);
if(p != m.end())
cout << "Its ASCII value is " << p->second;
else
cout << "Key not in map.\n";
return 0;
}
/*
Its ASCII value is 71
*/

</source>

==Define string-string map and loop through the value key-pair==

<source lang="cpp">

#include <iostream>
#include <map>
#include <string>
using namespace std;
int main( ) {
map<string, string> strMap;
strMap["Monday"] = "1";
strMap["Tuesday"] = "2";
strMap["Wednesday"] = "3";
strMap["Thursday"] = "4";
strMap["Friday"] = "5";
strMap["Saturday"] = "6";
strMap.insert(pair<string, string>("Sunday", "7"));
for (map<string, string>::iterator p = strMap.begin( );
p != strMap.end( ); ++p ) {
cout << "English: " << p->first<< ", #: " << p->second << endl;
}
cout << endl;
}
/*
English: Friday, #: 5
English: Monday, #: 1
English: Saturday, #: 6
English: Sunday, #: 7
English: Thursday, #: 4
English: Tuesday, #: 2
English: Wednesday, #: 3

*/

</source>

==Demonstrating an STL map==

<source lang="cpp">

#include <iostream>
#include <map>
#include <string>
using namespace std;
int main()
{
map<string, long> directory;
directory["A"] = 1234567;
directory["B"] = 9876543;
directory["C"] = 3459876;

string name = "A";
if (directory.find(name) != directory.end())
cout << "The phone number for " << name
<< " is " << directory[name] << "\n";
else
cout << "Sorry, no listing for " << name << "\n";
return 0;
}
/*
The phone number for A is 1234567
*/

</source>

==Get the size of a map==

<source lang="cpp">
#include <map>
#include <iostream>
#include <string>
using namespace std;
typedef map<string, int> STRING2INT;
int main(void)
{
STRING2INT DateMap;
STRING2INT::iterator DateIterator;
string DateBuffer;
DateMap["January"] = 1;
DateMap["February"] = 2;
DateMap["March"] = 3;
DateMap["April"] = 4;
DateMap["May"] = 5;
DateMap["June"] = 6;
DateMap["July"] = 7;
DateMap["August"] = 8;
DateMap["September"] = 9;
DateMap["October"] = 10;
DateMap["November"] = 11;
DateMap["December"] = 12;
if(!DateMap.empty())
cout << "DateMap has " << DateMap.size() << " entries" << endl;
else
cout << "DateMap is empty" << endl;
}

</source>

==Multiple map==

<source lang="cpp">

/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <map>
#include <string>
#include <iomanip>
using namespace std;
int main()
{
// define multimap type as string/string dictionary
typedef multimap<string,string> StrStrMMap;
// create empty dictionary
StrStrMMap dict;
// insert some elements in random order
dict.insert(make_pair("day","Tag"));
dict.insert(make_pair("strange","fremd"));
dict.insert(make_pair("car","Auto"));
dict.insert(make_pair("smart","elegant"));
dict.insert(make_pair("trait","Merkmal"));
dict.insert(make_pair("strange","seltsam"));
dict.insert(make_pair("smart","raffiniert"));
dict.insert(make_pair("smart","klug"));
dict.insert(make_pair("clever","raffiniert"));
// print all elements
StrStrMMap::iterator pos;
cout.setf (ios::left, ios::adjustfield);
cout << " " << setw(10) << "english "
<< "german " << endl;
cout << setfill("-") << setw(20) << ""
<< setfill(" ") << endl;
for (pos = dict.begin(); pos != dict.end(); ++pos) {
cout << " " << setw(10) << pos->first.c_str()
<< pos->second << endl;
}
cout << endl;
// print all values for key "smart"
string word("smart");
cout << word << ": " << endl;
for (pos = dict.lower_bound(word);
pos != dict.upper_bound(word); ++pos) {
cout << " " << pos->second << endl;
}
// print all keys for value "raffiniert"
word = ("raffiniert");
cout << word << ": " << endl;
for (pos = dict.begin(); pos != dict.end(); ++pos) {
if (pos->second == word) {
cout << " " << pos->first << endl;
}
}
}
/*
english german
--------------------
car Auto
clever raffiniert
day Tag
smart elegant
smart raffiniert
smart klug
strange fremd
strange seltsam
trait Merkmal
smart:
elegant
raffiniert
klug
raffiniert:
clever
smart
*/

</source>

==Put value to map with assignment==

<source lang="cpp">
#include <map>
#include <iostream>
#include <string>
using namespace std;
typedef map<string, int> STRING2INT;
int main(void)
{
STRING2INT DateMap;
STRING2INT::iterator DateIterator;
string DateBuffer;
DateMap["January"] = 1;
DateMap["February"] = 2;
DateMap["March"] = 3;
DateMap["April"] = 4;
DateMap["May"] = 5;
DateMap["June"] = 6;
DateMap["July"] = 7;
DateMap["August"] = 8;
DateMap["September"] = 9;
DateMap["October"] = 10;
DateMap["November"] = 11;
DateMap["December"] = 12;
if(!DateMap.empty())
cout << "DateMap has " << DateMap.size() << " entries" << endl;
else
cout << "DateMap is empty" << endl;
}

</source>

==Store objects in a map==

<source lang="cpp">

#include <iostream>
#include <map>
#include <cstring>
using namespace std;
class Name {
char str[40];
public:
Name() {
strcpy(str, "");
}
Name(char *s) {
strcpy(str, s);
}
char *get() {
return str;
}
};
// Must define less than relative to Name objects.
bool operator<(Name a, Name b)
{
return strcmp(a.get(), b.get()) < 0;
}
class Number {
char str[80];
public:
Number() {
strcmp(str, "");
}
Number(char *s) {
strcpy(str, s);
}
char *get() {
return str;
}
};

int main()
{
map<Name, Number> directory;
directory.insert(pair<Name, Number>(Name("T"),Number("555-4444")));
directory.insert(pair<Name, Number>(Name("C"),Number("555-3333")));
directory.insert(pair<Name, Number>(Name("J"),Number("555-2222")));
directory.insert(pair<Name, Number>(Name("R"),Number("555-1111")));
char str[80] = "T";
map<Name, Number>::iterator p;
p = directory.find(Name(str));
if(p != directory.end())
cout << "Phone number: " << p->second.get();
else
cout << "Name not in directory.\n";
return 0;
}
/*
Phone number: 555-4444
*/

</source>

==Use a map to create a phone directory.==

<source lang="cpp">
#include <iostream>
#include <map>
#include <cstring>
using namespace std;

class name {
char str[40];
public:
name() { strcpy(str, ""); }
name(char *s) { strcpy(str, s); }
char *get() { return str; }

};

bool operator<(name a, name b)
{
return strcmp(a.get(), b.get()) < 0;
}

class phoneNum {
char str[80];
public:
phoneNum() { strcmp(str, ""); }
phoneNum(char *s) { strcpy(str, s); }
char *get() { return str; }
};

int main()
{
map<name, phoneNum> directory;

directory.insert(pair<name, phoneNum>(name("A"), phoneNum("555-1111")));
directory.insert(pair<name, phoneNum>(name("B"), phoneNum("555-2222")));
directory.insert(pair<name, phoneNum>(name("C"), phoneNum("555-3333")));
directory.insert(pair<name, phoneNum>(name("D"), phoneNum("555-4444")));

map<name, phoneNum>::iterator p;

p = directory.find(name("A"));
if(p != directory.end())
cout << "Phone number: " << p->second.get();
else
cout << "Name not in directory.\n";

return 0;
}

</source>

==Use string as the key and value in a map==

<source lang="cpp">

#include <iostream>
#include <map>
#include <string>
using namespace std;
int main()
{
map<string, string> directory;
directory.insert(pair<string, string>("T", "555-4444"));
directory.insert(pair<string, string>("C", "555-3333"));
directory.insert(pair<string, string>("J", "555-2222"));
directory.insert(pair<string, string>("R", "555-1111"));
string s = "T";
map<string, string>::iterator p;
p = directory.find(s);
if(p != directory.end())
cout << "Phone number: " << p->second;
else
cout << "Name not in directory.\n";
return 0;
}
/*
Phone number: 555-4444
*/

</source>

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