STL algorithm Process for operating C++ STL containers: Choose the appropriate algorithm: Choose the STL algorithm based on the required operation, such as finding the maximum value, copying elements, or sorting. Determine input and output iterators: Specify the iterator ranges of the input and output containers. Provide a binary function object: define a functor to perform the desired element-wise operation. Calling an algorithm: Use the algorithm() function to call the selected algorithm, passing the iterator range and functor.

How to use STL algorithms to operate C++ STL containers

The Standard Template Library (STL) provides a powerful collection of algorithms in C++ for operating sequence containers (such as vector, list and map). These algorithms are designed to provide an efficient and reusable mechanism for performing common data processing tasks.

Basic Syntax

The STL algorithm follows the following syntax:

template<typename InputIterator, typename OutputIterator, typename Function>
OutputIterator algorithm(InputIterator first, InputIterator last, OutputIterator result, Function op);

Where:

• InputIterator and OutputIterator Specifies the iterator type of the input and output containers.
• first and last are the iterator ranges of the input container.
• result is the iterator of the output container.
• op is a binary function object (functor) used to perform operations on input elements.

Practical case

1. Find the maximum value

#include <algorithm>
#include <iostream>
#include <vector>

using namespace std;

int main() {
  vector<int> numbers = {1, 3, 5, 7, 9};

  auto max_value = *max_element(numbers.begin(), numbers.end());

  cout << "最大值：" << max_value << endl;

  return 0;
}

输出：

Maximum value: 9

**2. 复制元素**

include

include

include

using namespace std;

int main() {
vector vector copy;

copy.reserve(numbers.size()); // Reserve space to improve efficiency

copy_n(numbers.begin(), numbers.size(), back_inserter(copy));

for (int num : copy) {

cout << num << " ";

Copy after login

}

cout << endl;

return 0;
}

Output:

1 3 5 7 9

Copy after login

3. Sorting

#include 
#include 
#include 

using namespace std;

int main() {
  vector numbers = {5, 1, 3, 7, 2};

  sort(numbers.begin(), numbers.end());

  for (int num : numbers) {
    cout << num << " ";
  }

  cout << endl;

  return 0;
}

输出：

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1 2 3 5 7

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