在 C + + 中检查 std: : Vector < string > 是否包含某个值

有没有内置的函数告诉我，我的向量包含一个特定的元素或没有例如:。

std::vector<string> v;
v.push_back("abc");
v.push_back("xyz");


if (v.contains("abc")) // I am looking for one such feature, is there any
// such function or i need to loop through whole vector?

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小开

it's in <algorithm> and called std::find.

小开

std::find().

小开

最佳答案

You can use std::find as follows:

if (std::find(v.begin(), v.end(), "abc") != v.end())
{
// Element in vector.
}

To be able to use std::find: include <algorithm>.

小开

If your container only contains unique values, consider using std::set instead. It allows querying of set membership with logarithmic complexity.
```
 std::set<std::string> s;
s.insert("abc");
s.insert("xyz");
if (s.find("abc") != s.end()) { ...
```
If your vector is kept sorted, use std::binary_search, it offers logarithmic complexity as well.
If all else fails, fall back to std::find, which is a simple linear search.

小开

In C++11, you can use std::any_of instead.

An example to find if there is any zero in the array:

std::array<int,3> foo = {0,1,-1};
if ( std::any_of(foo.begin(), foo.end(), [](int i){return i==0;}) )
std::cout << "zero found...";