C++/STL Algorithms Modifying sequence operations/replace if

Replace value equal to 70 with 42 in a deque

<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.
*/

1. include <iostream>
2. include <set>
3. include <deque>
4. include <algorithm>

using namespace std; /* PRINT_ELEMENTS()

* - prints optional C-string optcstr followed by
* - all elements of the collection coll
* - separated by spaces
*/

template <class T> inline void PRINT_ELEMENTS (const T& coll, const char* optcstr="") {

   typename T::const_iterator pos;
   std::cout << optcstr;
   for (pos=coll.begin(); pos!=coll.end(); ++pos) {
       std::cout << *pos << " ";
   }
   std::cout << std::endl;

}

int main() {

   set<int,greater<int> > coll1;
   deque<int> coll2;
   // insert elements from 1 to 9
   for (int i=1; i<=9; ++i) {
       coll1.insert(i);
   }
   PRINT_ELEMENTS(coll1,"initialized: ");
   // transform all elements into coll2 by multiplying 10
   transform (coll1.begin(),coll1.end(),        // source
              back_inserter(coll2),             // destination
              bind2nd(multiplies<int>(),10));   // operation
   PRINT_ELEMENTS(coll2,"transformed: ");
   // replace value equal to 70 with 42
   replace_if (coll2.begin(),coll2.end(),       // range
               bind2nd(equal_to<int>(),70),     // replace criterion
               42);                             // new value
   PRINT_ELEMENTS(coll2,"replaced:    ");

}

/* 

initialized: 9 8 7 6 5 4 3 2 1 transformed: 90 80 70 60 50 40 30 20 10 replaced: 90 80 42 60 50 40 30 20 10

*/       
   
 </source>

std::replace_if with predicate

<source lang="cpp">

1. include <iostream>

using std::cout; using std::endl;

1. include <algorithm>
2. include <vector>
3. include <iterator>

bool greater9( int ); int main() {

  int a[ 10 ] = { 10, 2, 10, 4, 16, 6, 14, 8, 12, 10 };
  std::ostream_iterator< int > output( cout, " " );
  std::vector< int > v3( a, a + 10 ); // copy of a
  cout << "Vector v3 before replacing values greater than 9:\n   ";
  std::copy( v3.begin(), v3.end(), output );
  // replace values greater than 9 in v3 with 100
  std::replace_if( v3.begin(), v3.end(), greater9, 100 );
  cout << "\nVector v3 after replacing all values greater"
     << "\nthan 9 with 100s:\n   ";
  std::copy( v3.begin(), v3.end(), output );
  cout << endl;
  return 0;

} bool greater9( int x ) {

  return x > 9;

}

/* 

Vector v3 before replacing values greater than 9:

  10 2 10 4 16 6 14 8 12 10

Vector v3 after replacing all values greater than 9 with 100s:

  100 2 100 4 100 6 100 8 100 100
*/       
   
 </source>

Truncate numbers to fall between 0 and 255 inclusive

<source lang="cpp">

1. include <algorithm>
2. include <functional>
3. include <iomanip>
4. include <numeric>
5. include <string>
6. include <vector>
7. 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( ){

  vector<float> v( 5, 1 );
  partial_sum( v.begin(), v.end(), v.begin() );
  print( v);
  transform( v.begin(), v.end(), v.begin(),bind1st( multiplies<float>(), 100 ) );
  v.assign( v.size(), 100 );
  v[0] = -10;
  replace_if( v.begin(), v.end(),bind2nd( greater<float>(), 255 ), 255 );
  replace_if( v.begin(), v.end(), bind2nd( less<float>(), 0 ), 0 );
  print( v);

}

 </source>