c – any_of Versus find_if

C 11引入了any_of算法.

这似乎像find_if完全一样.

说我有一个函子：function< bool(int)> FOO;
和一个数组：vector< int>酒吧;

看来这两个电话是完全一样的：

any_of(bar.begin(),bar.end(),foo);

和

bar.end() != find_if(bar.begin(),foo);

我进一步感觉,all_of和none_of可以通过否定find_if语句来实现.

这些算法正是在这里做比较才能为我们结束,还是有一个有用的我不明白？

解决方法

我相信你是对的,他们只是更方便的功能接口,可以通过其他方式实现.

将它们添加到标准(N2666)中的建议说：

These three algorithms provide the ordinary mathematical operations ∀,∃,and ∄: given a
range and a predicate,determine whether that predicate is true for all elements; whether
there exists an element for which the predicate is true; or whether there exist no elements
for which the predicate is true. Strictly speaking there is no need to provide all three of
these algorithms (!none_of and any_of are equivalent),but all three of these operations
feel equally fundamental.

这些名称比包含find_if和(in)等式的表达更自然,更容易阅读(肯定是非专家C程序员).

GCC的标准库通过简单地调用其他函数实现它们：

all_of(first,last,pred)是return last == std :: find_if_not(first,pred);

none_of(first,pred)是return last == std :: find_if(first,pred);

any_of(first,pred)是return！none_of(first,pred);