C++ STL (Standard Template Library) Tutorial and Examples

#include <iostream>
#include <vector>
#include <string>

using namespace std;

main()
{
   vector<string> SS;

   SS.push_back("The number is 10");
   SS.push_back("The number is 20");
   SS.push_back("The number is 30");

   cout << "Loop by index:" << endl;

   int ii;
   for(ii=0; ii < SS.size(); ii++)
   {
      cout << SS[ii] << endl;
   }

   cout << endl << "Constant Iterator:" << endl;

   vector<string>::const_iterator cii;
   for(cii=SS.begin(); cii!=SS.end(); cii++)
   {
      cout << *cii << endl;
   }

   cout << endl << "Reverse Iterator:" << endl;

   vector<string>::reverse_iterator rii;
   for(rii=SS.rbegin(); rii!=SS.rend(); ++rii)
   {
      cout << *rii << endl;
   }

   cout << endl << "Sample Output:" << endl;

   cout << SS.size() << endl;
   cout << SS[2] << endl;

   swap(SS[0], SS[2]);
   cout << SS[2] << endl;
}

#include <iostream>
#include <vector>

using namespace std;

main()
{
   // Declare size of two dimensional array and initialize.
   vector< vector<int> > vI2Matrix(3, vector<int>(2,0));    

   vI2Matrix[0][0] = 0;
   vI2Matrix[0][1] = 1;
   vI2Matrix[1][0] = 10;
   vI2Matrix[1][1] = 11;
   vI2Matrix[2][0] = 20;
   vI2Matrix[2][1] = 21;

   cout << "Loop by index:" << endl;

   int ii, jj;
   for(ii=0; ii < 3; ii++)
   {
      for(jj=0; jj < 2; jj++)
      {
         cout << vI2Matrix[ii][jj] << endl;
      }
   }
}
      

#include <iostream>
#include <vector>

using namespace std;

main()
{
                               // Vector length of 3 initialized to 0
   vector<int> vI1Matrix(3,0);

                               // Vector length of 4 initialized to hold another 
                               // vector vI1Matrix which has been initialized to 0
   vector< vector<int> > vI2Matrix(4, vI1Matrix);

                               // Vector of length 5 containing two dimensional vectors
   vector< vector< vector<int> > > vI3Matrix(5, vI2Matrix);

   ...
          

#include <iostream>
#include <vector>

using namespace std;

main()
{
   vector< vector< vector<int> > > vI3Matrix(2, vector< vector<int> > (3, vector<int>(4,0)) );

   for(int kk=0; kk<4; kk++)
   {
      for(int jj=0; jj<3; jj++)
      {
         for(int ii=0; ii<2; ii++)
         {
            cout << vI3Matrix[ii][jj][kk] << endl;
         }
      }
   }
}
         

#include <iostream>
#include <vector>

using namespace std;

main()
{
   vector< vector<int> > vI2Matrix;    // Declare two dimensional array
   vector<int> A, B;
   vector< vector<int> >::iterator iter_ii;
   vector<int>::iterator                 iter_jj;

   A.push_back(10);
   A.push_back(20);
   A.push_back(30);
   B.push_back(100);
   B.push_back(200);
   B.push_back(300);

   vI2Matrix.push_back(A);
   vI2Matrix.push_back(B);

   cout << endl << "Using Iterator:" << endl;

   for(iter_ii=vI2Matrix.begin(); iter_ii!=vI2Matrix.end(); iter_ii++)
   {
      for(iter_jj=(*iter_ii).begin(); iter_jj!=(*iter_ii).end(); iter_jj++)
      {
         cout << *iter_jj << endl;
      }
   }
}
          

// Standard Template Library example

#include <iostream>
#include <list>
using namespace std;

// Simple example uses type int

main()
{
   list<int> L;
   L.push_back(0);              // Insert a new element at the end
   L.push_front(0);             // Insert a new element at the beginning
   L.insert(++L.begin(),2);     // Insert "2" before position of first argument
                                // (Place before second argument)
   L.push_back(5);
   L.push_back(6);

   list<int>::iterator i;

   for(i=L.begin(); i != L.end(); ++i) cout << *i << " ";
   cout << endl;
   return 0;
}
      

// Standard Template Library example using a class.

#include <iostream>
#include <list>
using namespace std;

// The List STL template requires overloading operators =, == and <.

class AAA
{
   friend ostream &operator<<(ostream &, const AAA &);

   public:
      int x;
      int y;
      float z;

      AAA();
      AAA(const AAA &);
      ~AAA(){};
      AAA &operator=(const AAA &rhs);
      int operator==(const AAA &rhs) const;
      int operator<(const AAA &rhs) const;
};

AAA::AAA()   // Constructor
{
   x = 0;
   y = 0;
   z = 0;
}

AAA::AAA(const AAA &copyin)   // Copy constructor to handle pass by value.
{                             
   x = copyin.x;
   y = copyin.y;
   z = copyin.z;
}

ostream &operator<<(ostream &output, const AAA &aaa)
{
   output << aaa.x << ' ' << aaa.y << ' ' << aaa.z << endl;
   return output;
}

AAA& AAA::operator=(const AAA &rhs)
{
   this->x = rhs.x;
   this->y = rhs.y;
   this->z = rhs.z;
   return *this;
}

int AAA::operator==(const AAA &rhs) const
{
   if( this->x != rhs.x) return 0;
   if( this->y != rhs.y) return 0;
   if( this->z != rhs.z) return 0;
   return 1;
}

// This function is required for built-in STL list functions like sort
int AAA::operator<(const AAA &rhs) const
{
   if( this->x == rhs.x && this->y == rhs.y && this->z < rhs.z) return 1;
   if( this->x == rhs.x && this->y < rhs.y) return 1;
   if( this->x < rhs.x ) return 1;
   return 0;
}

main()
{
   list<AAA> L;
   AAA Ablob ;

   Ablob.x=7;
   Ablob.y=2;
   Ablob.z=4.2355;
   L.push_back(Ablob);  // Insert a new element at the end

   Ablob.x=5;
   L.push_back(Ablob);  // Object passed by value. Uses default member-wise
                        // copy constructor
   Ablob.z=3.2355;
   L.push_back(Ablob); 

   Ablob.x=3;
   Ablob.y=7;
   Ablob.z=7.2355;
   L.push_back(Ablob); 

   list<AAA>::iterator i;

   cout << "Print x: " << endl;
   for(i=L.begin(); i != L.end(); ++i) cout << (*i).x << " "; // print member
   cout << endl << endl;      

   cout << "Print x, y, z: " << endl;
   for(i=L.begin(); i != L.end(); ++i) cout << *i; // print with overloaded operator
   cout << endl;

   cout << "Sorted: " << endl;
   L.sort();
   for(i=L.begin(); i != L.end(); ++i) cout << *i; // print with overloaded operator
   cout << endl;

   cout << "Iterate in Reverse: " << endl;
   list<AAA>::reverse_iterator ri;
   for(ri=L.rbegin(); ri != L.rend(); ++ri) cout << *ri; // print with overloaded operator
   cout << endl;

   cout << "Remove where x=5: " << endl;
   for(i=L.begin(); i != L.end(); )       // Don't increment iterator here
       if( (*i).x == 5 ) i = L.erase(i);  // Returns iterator to the next item in the list
       else ++i;                          // Increment iterator here
   for(i=L.begin(); i != L.end(); ++i) cout << *i; // print with overloaded operator
   cout << endl;

   return 0;
}