C++/STL Algorithms Helper/bind2nd
Содержание
Count vowels in a sentence
#include <algorithm>
#include <functional>
#include <iomanip>
#include <numeric>
#include <string>
#include <vector>
#include <iostream>
using namespace std;
template <class T>
void print(T& c){
for( typename T::iterator i = c.begin(); i != c.end(); i++ ){
std::cout << *i << endl;
}
}
bool in_string( char c, const string target ){
return target.find( c ) != string::npos;
}
int main( ){
const string vowels( "aeiouAEIOU" );
string phrase( "The quick brown fox jumps over the lazy dog." );
cout << "\nThere are " << count_if( phrase.begin(), phrase.end(),
bind2nd( ptr_fun( in_string ), vowels ) )
<< " vowels in \n\"" << phrase << "\"\n";
}
Demonstrate bind2nd()
#include <iostream>
#include <list>
#include <functional>
#include <algorithm>
using namespace std;
int main()
{
list<int> lst;
list<int>::iterator p, endp;
for(int i=1; i < 20; i++) lst.push_back(i);
cout << "Original sequence:\n";
p = lst.begin();
while(p != lst.end()) {
cout << *p << " ";
p++;
}
cout << endl;
endp = remove_if(lst.begin(), lst.end(),
bind2nd(greater<int>(), 8));
cout << "Resulting sequence:\n";
p = lst.begin();
while(p != endp) {
cout << *p << " ";
p++;
}
return 0;
}
/*
Original sequence:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Resulting sequence:
1 2 3 4 5 6 7 8
*/
multiply by 100 to get a percent
#include <algorithm>
#include <functional>
#include <iomanip>
#include <vector>
#include <iostream>
using namespace std;
template <class T>
void print(T& c){
for( typename T::iterator i = c.begin(); i != c.end(); i++ ){
std::cout << *i << endl;
}
}
int main()
{
const float d1[] = { 1.11, 2.22, 3.33, 4.44, 5.55 };
const float d2[] = { 6.66, 7.77, 8.88, 9.99, 1.11 };
vector<float> v2( d2,d2 + sizeof( d2 ) / sizeof( d2[0] ) );
vector<float> v1( d1,d1 + sizeof( d1 ) / sizeof( d1[0] ) );
vector<float> change( v2.size() );
// multiply by 100 to get a percent
transform( change.begin(), change.end(), change.begin(),bind2nd( multiplies<float>(), 100.0f ) );
print( change );
}
transform, bind2nd and modulus
#include <algorithm>
#include <functional>
#include <cstdlib>
#include <vector>
#include <iostream>
using namespace std;
template <class T>
void print(T& c){
for( typename T::iterator i = c.begin(); i != c.end(); i++ ){
std::cout << *i << endl;
}
}
int main( )
{
vector<int> random( 8 );
generate( random.begin(), random.end(), rand );
print( random);
transform( random.begin(), random.end(), random.begin(),bind2nd( modulus<int>(), 6 ) );
print( random );
}
transform, bind2nd and plus
#include <algorithm>
#include <functional>
#include <cstdlib>
#include <vector>
#include <iostream>
using namespace std;
template <class T>
void print(T& c){
for( typename T::iterator i = c.begin(); i != c.end(); i++ ){
std::cout << *i << endl;
}
}
int main( )
{
vector<int> random( 8 );
generate( random.begin(), random.end(), rand );
print( random);
transform( random.begin(), random.end(), random.begin(),bind2nd( plus<int>(), 1 ) );
print( random );
}
Use the generic count algorithm with predicate: Determine the number of array elements that are not equal to 1
#include <iostream>
#include <cassert>
#include <algorithm>
#include <functional>
using namespace std;
int main()
{
int a[] = {0, 0, 0, 1, 1, 1, 2, 2, 2};
int final_count = count_if(&a[0], &a[9], bind2nd(not_equal_to<int>(), 1));
cout << final_count << endl;
return 0;
}
/*
6
*/