в 14:21, 25 мая 2010

2010-05-25T14:21:06Z

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2010-05-25T10:25:55Z

1 версия: Импорт контента...

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==find all elements in a map by value==

<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 )
{} // empty
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};
const int num_appliances = 3;
vector<PC> v;
for( int i = 0; i < num_appliances; ++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;
const PC::PC_type desired_type = PC::IBM;
// find all elements by value
bool found = false;
for( site = sold.begin(); site != sold_end; ++site )
if( site->second.appliance() == desired_type ){
found = true;
site->second.print();
}
if( !found )
cout << "No IBMs sold\n";
}
inline
bool greater_model( const pair<PC::PC_type,PC> p,int min_model )
{ return p.second.model() >= min_model; }

</source>

==Find product in a map by its number==

<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 )
{} // empty
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};
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+3, 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();
const int desired_serial = 33447;
site = sold.find( desired_serial );
if( site != sold_end )
site->second.print();
else
cout << "There is no appliance with serial number " << desired_serial << endl;
}
inline
bool greater_model( const pair<PC::PC_type,PC> p,int min_model )
{ return p.second.model() >= min_model; }

</source>

==Find product in a map by its type==

<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 )
{} // empty
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};
const int num_appliances = 3;
vector<PC> v;
for( int i = 0; i < num_appliances; ++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();
const PC::PC_type desired_type = PC::IBM;

for( site = sold.begin(); site != sold_end; ++site )
if( site->second.appliance() == desired_type )
break;
if( site != sold_end )
site->second.print();
else
cout << "No IBMs sold\n";
}
inline
bool greater_model( const pair<PC::PC_type,PC> p,int min_model )
{ return p.second.model() >= min_model; }

</source>

==Find the value with a given key==

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

int main()
{
map<char, int> m;
int i;

for(i=0; i<26; i++) {
m.insert(pair<char, int>("A"+i, 65+i));
}

char ch;
cout << "Enter key: ";
cin >> ch;

map<char, int>::iterator p;

p = m.find(ch);
if(p != m.end())
cout << "Its ASCII value is " << p->second;
else
cout << "Key not in map.\n";

return 0;
}

</source>

==Map find==

<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 <algorithm>
#include <map>
using namespace std;
/* function object to check the value of a map element
*/
template <class K, class V>
class value_equals {
private:
V value;
public:
// constructor (initialize value to compare with)
value_equals (const V& v)
: value(v) {
}
// comparison
bool operator() (pair<const K, V> elem) {
return elem.second == value;
}
};
int main()
{
typedef map<float,float> FloatFloatMap;
FloatFloatMap coll;
FloatFloatMap::iterator pos;
// fill container
coll[1]=7;
coll[2]=4;
coll[3]=2;
coll[4]=3;
coll[5]=6;
coll[6]=1;
coll[7]=3;
// search an element with key 3.0
pos = coll.find(3.0); // logarithmic complexity
if (pos != coll.end()) {
cout << pos->first << ": "
<< pos->second << endl;
}
}
/*
3: 2
*/

</source>

==map: find_if==

<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 <algorithm>
#include <map>
using namespace std;
/* function object to check the value of a map element
*/
template <class K, class V>
class value_equals {
private:
V value;
public:
// constructor (initialize value to compare with)
value_equals (const V& v)
: value(v) {
}
// comparison
bool operator() (pair<const K, V> elem) {
return elem.second == value;
}
};
int main()
{
typedef map<float,float> FloatFloatMap;
FloatFloatMap coll;
FloatFloatMap::iterator pos;
// fill container
coll[1]=7;
coll[2]=4;
coll[3]=2;
coll[4]=3;
coll[5]=6;
coll[6]=1;
coll[7]=3;
// search an element with value 3.0
pos = find_if(coll.begin(),coll.end(), // linear complexity
value_equals<float,float>(3.0));
if (pos != coll.end()) {
cout << pos->first << ": "
<< pos->second << endl;
}
}
/*
4: 3
*/

</source>

==map find with custom object==

<source lang="cpp">
#include <map>
#include <iostream>
using namespace std;
class Data
{
public:
Data(int val = 0) { mVal = val; }
int getVal() const { return mVal; }
void setVal(int val) {mVal = val; }
protected:
int mVal;
};
int main(int argc, char** argv)
{
map<int, Data> dataMap;
dataMap[1] = Data(4);
dataMap[1] = Data(6);
map<int, Data>::iterator it = dataMap.find(1);
if (it != dataMap.end()) {
it->second.setVal(100);
}
return (0);
}

</source>

==map look up==

<source lang="cpp">
#include <map>
#include <iostream>
using namespace std;
class Data
{
public:
Data(int val = 0) { mVal = val; }
int getVal() const { return mVal; }
void setVal(int val) {mVal = val; }
protected:
int mVal;
};
int main(int argc, char** argv)
{
map<int, Data> dataMap;
dataMap[1] = Data(4);
dataMap[1] = Data(6);
dataMap[1].setVal(100);
return (0);
}

</source>

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