How can the application of C++ functions in multi-threaded programming improve efficiency?

C functions can improve multi-threaded programming efficiency in the following ways: 1. Encapsulate code logic to improve reusability; 2. Execute functions in multiple threads at the same time to improve concurrency; 3. Limit access to shared resources to avoid Competition for resources. By splitting blocks of code into separate threads and taking advantage of multi-core processors, multiple tasks can be performed simultaneously, greatly improving application efficiency.

Use C functions to implement multi-threaded programming to improve efficiency

In multi-threaded programming, C functions provide powerful tools to improve application efficiency. By splitting blocks of code into separate threads, programs can perform multiple tasks simultaneously, taking full advantage of multi-core processors.

Multi-threading Basics

A thread is a lightweight execution unit that shares the same memory space with the process. In C, threads can be created and managed through the std::thread class. The following code snippet shows how to create a new thread:

#include <thread>

void thread_function() {
  // 执行代码块
}

int main() {
  std::thread t(thread_function);
  t.join();
  return 0;
}

thread_function is a function that contains a block of code to be executed. t.join() Wait for the thread to complete execution before continuing the execution of the main thread.

Use functions to improve efficiency

C functions improve the efficiency of multi-threaded programming in the following ways:

• Encapsulation code Logic: Functions can encapsulate code blocks into modular units, making the code easy to reuse and maintain.
• Improve concurrency: By executing functions in multiple threads at the same time, the concurrency of the application can be improved.
• Avoid resource competition: Functions can limit access to shared resources and prevent resource competition between threads.

Practical case: Image converter

The following is a practical case of using C functions for multi-thread programming to convert image formats:

#include <vector>
#include <thread>
#include <future>
#include <iostream>

using namespace std;

vector<string> image_files;
future<bool> thread_results[10];

void convert_image(int index) {
  // 转换 image_files 中的图片
  // 并将结果存储在 thread_results[index] 中
  thread_results[index] = async(convert_image, index);
}

int main() {
  // 加载 image_files
  ...

  for (int i = 0; i < image_files.size(); i++) {
    convert_image(i);
  }

  for (int i = 0; i < image_files.size(); i++) {
    // 检查 thread_results[i] 的结果
  }

  return 0;
}

In this example, the convert_image function encapsulates the image conversion logic. By creating 10 threads and executing the convert_image function separately, multiple images can be converted simultaneously, significantly increasing the conversion speed. async The function is used to execute the convert_image function asynchronously and returns a future, which is used to obtain the execution result.

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