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

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Replace values in vector with another value with replace()

#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
bool greater9( int );
int main()
{ 
   const int SIZE = 10;
   int a[ SIZE ] = { 10, 2, 10, 4, 16, 6, 14, 8, 12, 10 };
   // Replace 10s in v1 with 100
   vector< int > v1( a, a + SIZE );
   replace( v1.begin(), v1.end(), 10, 100 );
   return 0;
}
bool greater9( int x ){
   return x > 9;
}

Use replace to replace all elements with value 6 with 42

/* 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 <vector>
#include <deque>
#include <list>
#include <set>
#include <map>
#include <string>
#include <algorithm>
#include <iterator>
#include <functional>
#include <numeric>
/* 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;
}
/* INSERT_ELEMENTS (collection, first, last)
 * - fill values from first to last into the collection
 * - NOTE: NO half-open range
 */
template <class T>
inline void INSERT_ELEMENTS (T& coll, int first, int last)
{
    for (int i=first; i<=last; ++i) {
        coll.insert(coll.end(),i);
    }
}
using namespace std;
int main()
{
    list<int> coll;
    INSERT_ELEMENTS(coll,2,7);
    INSERT_ELEMENTS(coll,4,9);
    PRINT_ELEMENTS(coll,"coll: ");
    // replace all elements with value 6 with 42
    replace (coll.begin(), coll.end(),     // range
             6,                            // old value
             42);                          // new value
    PRINT_ELEMENTS(coll,"coll: ");
}
coll: 2 3 4 5 6 7 4 5 6 7 8 9
coll: 2 3 4 5 42 7 4 5 42 7 8 9

Use replace to replace all elements with value less than 5 with 0

/* 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 <vector>
#include <deque>
#include <list>
#include <set>
#include <map>
#include <string>
#include <algorithm>
#include <iterator>
#include <functional>
#include <numeric>
/* 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;
}
/* INSERT_ELEMENTS (collection, first, last)
 * - fill values from first to last into the collection
 * - NOTE: NO half-open range
 */
template <class T>
inline void INSERT_ELEMENTS (T& coll, int first, int last)
{
    for (int i=first; i<=last; ++i) {
        coll.insert(coll.end(),i);
    }
}
using namespace std;
int main()
{
    list<int> coll;
    INSERT_ELEMENTS(coll,2,7);
    INSERT_ELEMENTS(coll,4,9);
    PRINT_ELEMENTS(coll,"coll: ");
    // replace all elements with value less than 5 with 0
    replace_if (coll.begin(), coll.end(),  // range
                bind2nd(less<int>(),5),    // criterion for replacement
                0);                        // new value
    PRINT_ELEMENTS(coll,"coll: ");
}
coll: 2 3 4 5 6 7 4 5 6 7 8 9
coll: 0 0 0 5 6 7 0 5 6 7 8 9

Use replace() to replace elements in a vector

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
template<class InIter>
void show_range(const char *msg, InIter start, InIter end);
int main()
{
  vector<char> v;
  vector<char>::iterator itr, itr_end;
  for(int i=0; i<5; i++) {
    v.push_back("A"+i);
  }
  for(int i=0; i<5; i++) {
    v.push_back("A"+i);
  }
  show_range("Original contents of v:", v.begin(), v.end());
  
  // Replace B"s with X"s
  replace(v.begin(), v.end(), "B", "X");
  show_range("v after replacing B with X:", v.begin(), itr_end);
  return 0;
}
template<class InIter>
void show_range(const char *msg, InIter start, InIter end) {
  InIter itr;
  cout << msg << endl;
  for(itr = start; itr != end; ++itr){
    cout << *itr << endl;
  }
}

Use std::replace to replace elements in vector by value

#include <iostream>
using std::cout;
using std::endl;
#include <algorithm>
#include <vector>
#include <iterator>
int main()
{
   int a[ 10 ] = { 10, 2, 10, 4, 16, 6, 14, 8, 12, 10 };
   std::ostream_iterator< int > output( cout, " " );
   std::vector< int > v1( a, a + 10 ); // copy of a
   cout << "Vector v1 before replacing all 10s:\n   ";
   std::copy( v1.begin(), v1.end(), output );
   // replace all 10s in v1 with 100
   std::replace( v1.begin(), v1.end(), 10, 100 );
   cout << "\nVector v1 after replacing 10s with 100s:\n   ";
   std::copy( v1.begin(), v1.end(), output );
   cout << endl;
   return 0;
}
Vector v1 before replacing all 10s:
   10 2 10 4 16 6 14 8 12 10
Vector v1 after replacing 10s with 100s:
   100 2 100 4 16 6 14 8 12 100

Use the generic replace algorithm to replace all occurrences of R by S

#include <iostream>
#include <cassert>
#include <algorithm>
#include <vector>
#include <string>
using namespace std;
int main()
{
  string s("FERRARI");
  vector<char> vector1(s.begin(), s.end());
  
  replace(vector1.begin(), vector1.end(), "R", "S");
  for(int i=0;i<vector1.size();i++){
     cout << vector1[i] << " ";
  }
  return 0;
}
F E S S A S I

Using "std::replace" to replace value 5 by 8

#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
// The unary predicate used by replace_if to replace even numbers
bool IsEven (const int & nNum){
    return ((nNum % 2) == 0);
}
int main ()
{
    // Initialize a sample vector with 6 elements
    vector <int> v (6);
    // fill first 3 elements with value 8
    fill (v.begin (), v.begin () + 3, 8);
    // fill last 3 elements with value 5
    fill_n (v.begin () + 3, 3, 5);
    for (size_t nIndex = 0; nIndex < v.size (); ++ nIndex){
        cout << "Element [" << nIndex << "] = ";
        cout << v [nIndex] << endl;
    }
    cout << endl << "Using "std::replace" to replace value 5 by 8" << endl;
    replace (v.begin (), v.end (), 5, 8);
    for (size_t nIndex = 0; nIndex < v.size (); ++ nIndex){
        cout << "Element [" << nIndex << "] = ";
        cout << v [nIndex] << endl;
    }
    return 0;
}