insert
Syntax: #include <vector> iterator insert( iterator loc, const TYPE& val ); void insert( iterator loc, size_type num, const TYPE& val ); template<TYPE> void insert( iterator loc, input_iterator start, input_iterator end ); The insert() function either:
Note that inserting elements into a vector can be relatively time-intensive, since the underlying data structure for a vector is an array. In order to insert data into an array, you might need to displace a lot of the elements of that array, and this can take linear time. If you are planning on doing a lot of insertions into your vector and you care about speed, you might be better off using a container that has a linked list as its underlying data structure (such as a List or a Deque). For example, the following code uses the insert() function to splice four copies of the character 'C' into a vector of characters: // Create a vector, load it with the first 10 characters of the alphabet vector<char> alphaVector; for( int i=0; i < 10; i++ ) { alphaVector.push_back( i + 65 ); } // Insert four C's into the vector vector<char>::iterator theIterator = alphaVector.begin(); alphaVector.insert( theIterator, 4, 'C' ); // Display the vector for( theIterator = alphaVector.begin(); theIterator != alphaVector.end(); theIterator++ ) { cout << *theIterator; } This code would display: CCCCABCDEFGHIJ Here is another example of the insert() function. In this code, insert() is used to append the contents of one vector onto the end of another: vector<int> v1; v1.push_back( 0 ); v1.push_back( 1 ); v1.push_back( 2 ); v1.push_back( 3 ); vector<int> v2; v2.push_back( 5 ); v2.push_back( 6 ); v2.push_back( 7 ); v2.push_back( 8 ); cout << "Before, v2 is: "; for( int i = 0; i < v2.size(); i++ ) { cout << v2[i] << " "; } cout << endl; v2.insert( v2.end(), v1.begin(), v1.end() ); cout << "After, v2 is: "; for( int i = 0; i < v2.size(); i++ ) { cout << v2[i] << " "; } cout << endl; When run, this code displays: Before, v2 is: 5 6 7 8 After, v2 is: 5 6 7 8 0 1 2 3 Related topics:
|