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23.2.1 vector Sequence Container (continued)
Vector Element-Manipulation Functions
Figure 23.15 illustrates functions that enable retrieval and manipulation of the elements of a vector. Line 17 uses an overloaded vector constructor that takes two iterators as arguments to initialize integers. Remember that pointers into an array can be used as iterators. Line 17 initializes integers with the contents of array from location array up to—but not including—location array + SIZE.
1 // Fig. 23.15: Fig23_15.cpp 2 // Testing Standard Library vector class template 3 // element-manipulation functions. 4 #include <iostream> 5 using std::cout; 6 using std::endl; 7 8 #include <vector> // vector class-template definition 9 #include <algorithm> // copy algorithm 10 #include <iterator> // ostream_iterator iterator 11 #include <stdexcept> // out_of_range exception 12 13 int main() 14 { 15 const int SIZE = 6; 16 int array[ SIZE ] = { 1, 2, 3, 4, 5, 6 }; 17 std::vector< int > integers( array, array + SIZE ); 18 std::ostream_iterator< int > output( cout, " " ); 19 20 cout << "Vector integers contains: "; 21 std::copy( integers.begin(), integers.end(), output ); 22 23 cout << "\nFirst element of integers: " << integers.front() 24 << "\nLast element of integers: " << integers.back(); 25 26 integers[ 0 ] = 7; // set first element to 7 27 integers.at( 2 ) = 10; // set element at position 2 to 10 28 29 // insert 22 as 2nd element 30 integers.insert( integers.begin() + 1, 22 ); 31 32 cout << "\n\nContents of vector integers after changes: "; 33 std::copy( integers.begin(), integers.end(), output ); 34 35 // access out-of-range element 36 try 37 { 38 integers.at( 100 ) = 777; 39 } // end try 40 catch ( std::out_of_range outOfRange ) // out_of_range exception 41 { 42 cout << "\n\nException: " << outOfRange.what(); 43 } // end catch 44 45 // erase first element 46 integers.erase( integers.begin() ); 47 cout << "\n\nVector integers after erasing first element: "; 48 std::copy( integers.begin(), integers.end(), output ); 49 50 // erase remaining elements 51 integers.erase( integers.begin(), integers.end() ); 52 cout << "\nAfter erasing all elements, vector integers "; 53 << ( integers.empty() ? "is" : "is not" ) << " empty"; 54 55 // insert elements from array 56 integers.insert( integers.begin(), array, array + SIZE ); 57 cout << "\n\nContents of vector integers before clear: "; 58 std::copy( integers.begin(), integers.end(), output ); 59 60 // empty integers; clear calls erase to empty a collection 61 integers.clear(); 62 cout << "\nAfter clear, vector integers " 63 << ( integers.empty() ? "is" : "is not" ) << " empty" << endl; 64 return 0; 65 } // end main |
Vector integers contains: 1 2 3 4 5 6 First element of integers: 1 Last element of integers: 6 Contents of vector integers after changes: 7 22 2 10 4 5 6 Exception: invalid vector<T> subscript Vector integers after erasing first element: 22 2 10 4 5 6 After erasing all elements, vector integers is empty Contents of vector integers before clear: 1 2 3 4 5 6 After clear, vector integers is empty |
Fig. 23.15 vector class template element-manipulation functions.