The sample code below illustrates how to use the distance
STL function in Visual C++.
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Required Header
<iterator>
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Prototype
template<class Init, class Dist>
Dist distance(InIt first, InIt last, Dist& n);
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Description
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.
The Help file in Visual C++
4.2 incorrectly states that this function takes three parameters and returns
nothing.
NOTE: The class/parameter names in the prototype may not match the
version in the header file. Some have been modified to improve readability.
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Sample Code
NOTE: The first line in the sample code section says:
// Compile options needed: /GX
In VC++ .NET, /EHsc is set by default and is equivalent to /GX.
//////////////////////////////////////////////////////////////////////
//
// Compile options needed: /GX
//
// <filename> : distance.cpp
//
// Functions:
//
// distance()
//
// Written by Linda Koontz
// of Microsoft Product Support Services,
// Copyright (c) 1996 Microsoft Corporation. All rights reserved.
//////////////////////////////////////////////////////////////////////
#include <iostream>
#include <vector>
#include <iterator>
#include <string>
#if _MSC_VER > 1020 // if VC++ version is > 4.2
using namespace std; // std c++ libs implemented in std
#endif
// disable warning C4244: possible loss of data,
// okay to ignore
#pragma warning(disable: 4244)
#pragma warning (disable:4786)
typedef vector<string, allocator<string> > VTRLIST;
void 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;
}
Program Output is:
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
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For the same information about distance, visit the
following MSDN Web site:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vcstdlib/html/vcsampsampledistancestlsample.asp (http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vcstdlib/html/vcsampsampledistancestlsample.asp)Back to the top
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