STL function objects in C++ provide an efficient and flexible way to process container data, including unary function objects (accepting 1 parameter and returning a result), binary function objects (accepting 2 parameters and returning a result) and functors (overloaded function call operators). Function objects have the advantages of reusability, scalability, and performance optimization. In the actual case, the std::transform() function uses the std::negate<> function object to negate each element in the container. Tips include using inline function objects, creating custom lambda expressions, using function objects as return values, and understanding the semantics and limitations of function objects.
How to effectively use STL function objects in C++
The Standard Template Library (STL) provides a rich collection of function objects. Can be used for efficient and flexible operations on container data.
Types and uses of function objects
std ::negate<>
(reverse). std::plus<>
(addition). std::greater<>
(compare sizes). Advantages of using function objects
Practical case: using std::transform()
#include <algorithm> #include <iostream> #include <vector> int main() { std::vector<int> numbers = {1, 2, 3, 4, 5}; // 使用 std::negate<> 对容器中的每个元素取反 std::transform(numbers.begin(), numbers.end(), numbers.begin(), std::negate<>()); // 输出取反后的结果 for (auto number : numbers) { std::cout << number << " "; } return 0; }
Output:
-1 -2 -3 -4 -5
Tips for using function objects
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