distance (STL Samples)
Visual Studio 2005
Illustrates how to use the distance Standard Template Library (STL) function in Visual C++.
template<class Init, class Dist>
Dist distance(
InIt first,
InIt last,
Dist& n
);
 Note |
|---|
| The class/parameter names in the prototype do not match the version in the header file. Some have been modified to improve readability. |
This function returns the distance between two iterators by determining how many times the first iterator would need to be incremented until it was equal to the last iterator.
// distance.cpp
// compile with: /EHsc
#pragma warning (disable:4786)
#include <iostream>
#include <vector>
#include <iterator>
#include <string>
using namespace std;
typedef vector<string > VTRLIST;
int main() {
VTRLIST Vector;
VTRLIST::iterator iVector;
VTRLIST::difference_type dTheDiff;
Vector.push_back("A1");
Vector.push_back("B2");
Vector.push_back("C3");
Vector.push_back("D4");
Vector.push_back("E5");
Vector.push_back("F6");
Vector.push_back("G7");
// Print out the list
iVector=Vector.begin();
cout << "The list is: ";
for (int i = 0; i < 7 ; i++, iVector++)
cout << *iVector << " ";
// Initialize the iterator the first element"
iVector=Vector.begin();
cout << "\n\nAdvance to the 3rd element." << endl;
advance( iVector, 2);
cout << "The element is " << *iVector << endl;
dTheDiff = distance( Vector.begin(), iVector);
cout << "The distance from the beginning is " << dTheDiff << endl;
cout << "Calculate it in reverse order " << endl;
dTheDiff = distance( iVector, Vector.begin());
cout << "The distance is " << dTheDiff << endl;
cout << "\nUse distance() to count from the 3rd element to the end."
<< endl;
dTheDiff = distance( iVector, Vector.end());
// Note that end() returns one past the end of the sequence
cout << "The distance is " << dTheDiff << endl;
cout <<"\nUse distance() to count the total length." << endl;
dTheDiff = distance( Vector.begin(), Vector.end() );
cout << "The total distance is " << dTheDiff << endl;
}
The list is: A1 B2 C3 D4 E5 F6 G7 Advance to the 3rd element. The element is C3 The distance from the beginning is 2 Calculate it in reverse order The distance is -2 Use distance() to count from the 3rd element to the end. The distance is 5 Use distance() to count the total length. The total distance is 7
