释放给调用方返回的存储指针的所有权，并将存储的指针值设置为nullptr。

使用 release接管unique_ptr存储的原始指针的所有权。 调用方负责返回的指针的删除。 unique-ptr设置为空的默认构造状态。 在调用到release后，您可以将兼容类型的另一个指针分配到unique_ptr。

实例：

// stl_release_unique.cpp
// Compile by using: cl /W4 /EHsc stl_release_unique.cpp
#include <iostream>
#include <memory>struct Sample {int content_;Sample(int content) : content_(content) {std::cout << "Constructing Sample(" << content_ << ")" << std::endl;}~Sample() {std::cout << "Deleting Sample(" << content_ << ")" << std::endl;}
};void ReleaseUniquePointer() {// Use make_unique function when possible.  auto up1 = std::make_unique<Sample>(3);auto up2 = std::make_unique<Sample>(42);// Take over ownership from the unique_ptr up2 by using releaseauto ptr = up2.release();if (up2) {// This statement does not execute, because up2 is empty.std::cout << "up2 is not empty." << std::endl;}// We are now responsible for deletion of ptr.delete ptr;// up1 deletes its stored pointer when it goes out of scope.   
}int main() {ReleaseUniquePointer();
}

运行结果：

Constructing Sample(3)
Constructing Sample(42)
Deleting Sample(42)
Deleting Sample(3)

注意一点：

release后被接管的指针ptr,需要自己释放；而原先的up1离开了函数自动释放。