STLalgorithm算法find_if(19)
原文地址:http://www.cplusplus.com/reference/algorithm/find\_if/
function template
std::find_if
template <class InputIterator, class UnaryPredicate>
InputIterator find_if (InputIterator first, InputIterator last, UnaryPredicate pred);
Find element in range
Returns an iterator to the first element in the range [first,last)
for which pred returns true
. If no such element is found, the function returns last.
返回范围内第一个符合要求的元素的迭代器,如果没有,则返回last.
#include
#include
#include
#include
using namespace std;
void findif()
{
vector
array<double,2> ai{77,88};
cout<<"v1=";
for(int &i:v1)
cout<<i<<" ";
cout<<endl;
cout<<endl<<"ai=";
for(double &i:ai)
cout<<i<<" ";
cout<<endl<<"auto it=find\_if(v1.begin(),v1.end(),\[\](int i){return i%5==0;});"<<endl;
auto it=find\_if(v1.begin(),v1.end(),\[\](int i){return i%5==0;});
cout<<"\*(it-1)="<<\*(it-1)<<endl;
cout<<"\*it="<<\*it<<endl;
cout<<"\*(it+1)="<<\*(it+1)<<endl;
cout<<endl<<"auto it2=find\_first\_of(v1.begin(),v1.end(),ai.begin(),ai.end());"<<endl;
auto it2=find\_if(ai.begin(),ai.end(),\[\](int i){return i%100==0;});
cout<<"\*(it2-1)="<<\*(it2-1)<<endl;
cout<<"\*it2="<<\*it2<<endl;
cout<<"\*(it2+1)="<<\*(it2+1)<<endl;
}
运行截图:
The behavior of this function template is equivalent to:
1 | 1 |
1 | template<class InputIterator, class UnaryPredicate> |
Parameters
first, last
Input iterators to the initial and final positions in a sequence. The range used is [first,last)
, which contains all the elements between first and last, including the element pointed by first but not the element pointed by last.
匹配的范围。
pred
Unary function that accepts an element in the range as argument and returns a value convertible to bool
. The value returned indicates whether the element is considered a match in the context of this function.
The function shall not modify its argument.
This can either be a function pointer or a function object.
一元函数。(接受一个参数的一元函数,返回一个bool值)
Return value
An iterator to the first element in the range for which pred does not return false
.
If pred is false
for all elements, the function returns last.
返回范围内第一个符合要求的元素的迭代器,如果没有,则返回last.
Example
1 | 1 |
1 | // find_if example |
Output:
The first odd value is 25
Complexity
Up to linear in the distance between first and last: Calls pred for each element until a match is found.
Data races
Some (or all) of the objects in the range [first,last)
are accessed (once at most).
Exceptions
Throws if either pred or an operation on an iterator throws.
Note that invalid parameters cause undefined behavior.
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转载请注明出处:http://blog.csdn.net/qq844352155
author:天下无双
Email:coderguang@gmail.com
2014-9-12
于GDUT
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- 本文作者: royalchen
- 本文链接: http://www.royalchen.com/2016/02/24/stlalgorithm算法find-if19/
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