Demonstrating C++ Standard Library class template vector. - C++ STL

C++ examples for STL:vector

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Description

Demonstrating C++ Standard Library class template vector.

Demo Code

#include <iostream> 
#include <iomanip> 
#include <vector> 
using namespace std; 

void outputVector( const vector< int > & ); // display the vector 
void inputVector( vector< int > & ); // input values into the vector 

int main() //  ww  w. j  av a 2s .c o  m
{ 
   vector< int > integers1( 7 ); // 7-element vector< int > 
   vector< int > integers2( 10 ); // 10-element vector< int > 

   // print integers1 size and contents 
   cout << "Size of vector integers1 is " << integers1.size() << "\nvector after initialization:" << endl; 
   outputVector( integers1 ); 

   // print integers2 size and contents 
   cout << "\nSize of vector integers2 is " << integers2.size() << "\nvector after initialization:" << endl; 
   outputVector( integers2 ); 

   // input and print integers1 and integers2 
   cout << "\nEnter 17 integers:" << endl; 
   inputVector( integers1 ); 
   inputVector( integers2 ); 

   cout << "\nAfter input, the vectors contain:\n" << "integers1:" << endl; 
   outputVector( integers1 ); 
   cout << "integers2:" << endl; 
   outputVector( integers2 ); 

   // use inequality (!=) operator with vector objects 
   cout << "\nEvaluating: integers1 != integers2" << endl; 

   if ( integers1 != integers2 ) 
       cout << "integers1 and integers2 are not equal" << endl; 

   // create vector integers3 using integers1 as an initializer; print size and contents 
   vector< int > integers3( integers1 ); // copy constructor 

   cout << "\nSize of vector integers3 is " << integers3.size() 
       << "\nvector after initialization:" << endl; 
   outputVector( integers3 ); 

   // use overloaded assignment (=) operator 
   cout << "\nAssigning integers2 to integers1:" << endl; 
   integers1 = integers2; // assign integers2 to integers1 

   cout << "integers1:" << endl; 
   outputVector( integers1 ); 
   cout << "integers2:" << endl; 
   outputVector( integers2 ); 

   // use equality (==) operator with vector objects 
   cout << "\nEvaluating: integers1 == integers2" << endl; 

   if ( integers1 == integers2 ) 
       cout << "integers1 and integers2 are equal" << endl; 

   // use square brackets to create rvalue 
   cout << "\nintegers1[5] is " << integers1[ 5 ]; 

   // use square brackets to create lvalue 
   cout << "\n\nAssigning 1000 to integers1[5]" << endl; 
   integers1[ 5 ] = 1000; 
   cout << "integers1:" << endl; 
   outputVector( integers1 ); 

   // attempt to use out-of-range subscript 
   try 
   { 
       cout << "\nAttempt to display integers1.at( 15 )" << endl; 
       cout << integers1.at( 15 ) << endl; // ERROR: out of range 
   }
   catch ( out_of_range &ex ) 
   { 
       cout << "An exception occurred: " << ex.what() << endl; 
   }
}

void outputVector( const vector< int > &array ) 
{ 
   size_t i; // declare control variable 

   for ( i = 0; i < array.size(); ++i ) 
   { 
       cout << setw( 12 ) << array[ i ]; 
       if ( ( i + 1 ) % 4 == 0 ) // 4 numbers per row of output 
          cout << endl; 
   }

   if ( i % 4 != 0 ) 
       cout << endl; 
}

// input vector contents 
void inputVector( vector< int > &array ) 
{ 
   for ( size_t i = 0; i < array.size(); ++i ) 
       cin >> array[ i ]; 
}

Result


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