algorithm - STL C++

count()

Declaration

template <class InputIterator, class X>
InputIterator::difference_type count(
	InputIterator qFirst,
	InputIterator qLast,
	const X& kxrValue
);

Description

This function counts the number of entries equal to "kxrValue" that are in the range from "qFirst" up to the entry before "qLast."

Header Include

#include <algorithm>

Example

#include <iostream>
#include <vector>
#include <algorithm>

int main()
{
	using namespace std;

	// Create a vector instance
	vector<char> qV;
	qV.push_back('X');
	qV.push_back('o');
	qV.push_back('a');
	qV.push_back('X');
	qV.push_back('.');
	qV.push_back('n');
	qV.push_back('e');
	qV.push_back('t');

	vector<char>::iterator qIter;
	// Output the vector
	cout << "Vector: ";
	for (qIter = qV.begin(); qIter != qV.end(); ++qIter) {
		cout << *qIter;
	}
	cout << endl;

	// Count the 'X's and output the number
	vector<char>::iterator::difference_type qCount;
	qCount = count(qV.begin(), qV.end(), 'X');
	cout << "There are " << qCount << " X's in V." << endl;

	// Keep the window open
	cin.get();
	return 0;
}

Output

count() Output
 

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