find_if (STL Samples)
Illustrates how to use the find_if Standard Template Library (STL) function in Visual C++.
template<class InputIterator, class T, class Predicate> inline
InputIterator find_if(
InputIterator First,
InputIterator Last,
Predicate Predicate
)
Remarks
备注
The class/parameter names in the prototype do not match the version in the header file. Some have been modified to improve readability.
The find_if algorithm locates the first element in the range [First, Last) that causes the predicate to return true and returns the iterator positioned at that element, or Last if no such element was found.
Example
// findif.cpp
// compile with: /EHsc
// disable warning C4786: symbol greater than 255 characters,
// okay to ignore
#pragma warning(disable: 4786)
#include <algorithm>
#include <iostream>
using namespace std;
// returns true if n is an odd number
int IsOdd( int n)
{
return n % 2 ;
}
int main()
{
const int ARRAY_SIZE = 8 ;
int IntArray[ARRAY_SIZE] = { 1, 2, 3, 4, 4, 5, 6, 7 } ;
int *location ; // stores the position of the first
// element that is an odd number
int i ;
// print content of IntArray
cout << "IntArray { " ;
for(i = 0; i < ARRAY_SIZE; i++)
cout << IntArray[i] << ", " ;
cout << " }" << endl ;
// Find the first element in the range [first, last -1 ]
// that is an odd number
location = find_if(IntArray, IntArray + ARRAY_SIZE, IsOdd) ;
// print the location of the first element
// that is an odd number
if (location != IntArray + ARRAY_SIZE) // first odd element found
cout << "First odd element " << *location
<< " is at location " << location - IntArray << endl;
else // no odd numbers in the range
cout << "The sequence does not contain any odd numbers"
<< endl ;
}
Output
IntArray { 1, 2, 3, 4, 4, 5, 6, 7, }
First odd element 1 is at location 0
Requirements
Header: <algorithm>