C++ Programming Code Examples
C++ > Visual C++ 5.0 Standard C++ Library Code Examples
Find first of algorithm locates, within the range [first1, last1), the first element
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Find first of algorithm locates, within the range [first1, last1), the first element
find_first_of
Header
<algorithm>
template<class ForwardIterator1, class ForwardIterator2>
ForwardIterator1 find_first_of(ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2, ForwardIterator2 last2)
The algorithm locates, within the range [first1, last1), the first element of a sequence represented by the range [first2, last2). The non-predicate version uses the operator== for comparison.
template<class ForwardIterator1, class ForwardIterator2, class BinaryPredicate>
ForwardIterator1 find_first_of(ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2, ForwardIterator2 last2, BinaryPredicate pr)
The algorithm locates, within the range [first1, last1), the first element of a sequence represented by the range [first2, last2). The predicate version uses the predicate function pr for comparison.
Sample
#pragma warning (disable:4786)
#include <algorithm>
#include <iostream>
#include <cstring>
#include <functional>
int main()
{
char *input = "AABBCDEFAAEFFBB" ;
char *pattern = "BB" ;
int inputLen = strlen(input) ;
int patternLen = strlen(pattern) ;
char *pos ;
//find first occurence of pattern in input
//non-predicate version of find_first_of
pos = std::find_first_of(input, input+inputLen, pattern, pattern+patternLen) ;
std::cout << "non-predicate version of find_first_of" << std::endl ;
std::cout << "first occurence of " << pattern << " in " << input
<< " is at position " << (pos - input) << std::endl ;
//find first occurence of pattern in input
//predicate version of find_first_of
pos = std::find_first_of(input, input+inputLen, pattern, pattern+patternLen, std::equal_to<char>()) ;
std::cout << "\n\npredicate version of find_first_of" << std::endl ;
std::cout << "first occurence of " << pattern << " in " << input
<< " is at position " << (pos - input) << std::endl ;
//find last occurence of pattern in input
//non-predicate version of find_end
pos = std::find_end(input, input+inputLen, pattern, pattern+patternLen) ;
std::cout << "\n\nnon-predicate version of find_end" << std::endl ;
std::cout << "last occurence of " << pattern << " in " << input
<< " is at position " << (pos - input) << std::endl ;
//find last occurence of pattern in input
//predicate version of find_end
pos = std::find_end(input, input+inputLen, pattern, pattern+patternLen, std::equal_to<char>()) ;
std::cout << "\n\npredicate version of find_end" << std::endl ;
std::cout << "first occurence of " << pattern << " in " << input
<< " is at position " << (pos - input) << std::endl ;
return 0 ;
}
Program Output
non-predicate version of find_first_of
first occurence of BB in AABBCDEFAAEFFBB is at position 2
predicate version of find_first_of
first occurence of BB in AABBCDEFAAEFFBB is at position 2
non-predicate version of find_end
last occurence of BB in AABBCDEFAAEFFBB is at position 13
predicate version of find_end
first occurence of BB in AABBCDEFAAEFFBB is at position 13
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Find element from set in range. Returns an iterator to the first element in the range [first1,last1) that matches any of the elements in [first2,last2). If no such element is found, the function returns last1. The elements in [first1,last1) are sequentially compared to each of the values in [first2,last2) using operator== (or pred, in version (2)), until a pair matches. std::find_first_of is used to compare elements between two containers. It compares all the elements in a range [first1,last1) with the elements in the range [first2,last2), and if any of the elements present in the second range is found in the first one , then it returns an iterator to that element. If there are more than one element common in both the ranges, then an iterator to the first common element present in the first container is returned. In case there is no match, then iterator pointing to last1 is returned.
Find last subsequence in range. Searches the range [first1,last1) for the last occurrence of the sequence defined by [first2,last2), and returns an iterator to its first element, or last1 if no occurrences are found. std::find_end is used to find the last occurrence of a sub-sequence inside a container. It searches the range [first1,last1) for the last occurrence of the sequence defined by [first2,last2), and returns an iterator to its first element, or last1 if no occurrences are found. The elements in both ranges are compared sequentially using operator== (or pred, in version (2)): A subsequence of [first1,last1) is considered a match only when this is true for all the elements of [first2,last2). This function returns the last of such occurrences. For an algorithm that returns the first instead, see search.
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