How Can I Detect the Number of CPU Cores in Different Programming Languages and Environments?

Detecting the Number of CPU Cores in Various Programming Environments

Introduction

Determining the number of cores on a machine is a crucial aspect for optimizing code performance and resource allocation. While there is no universal solution across all platforms, there are platform-specific methods available.

C 11 and Later

C 11 introduces the std::thread::hardware_concurrency() function, providing a standardized way to retrieve the number of hardware threads. This method is recommended for cross-platform compatibility.

#include <thread>

const auto processor_count = std::thread::hardware_concurrency();

Pre-C 11 Alternative

Prior to C 11, platform-specific methods are required.

• Win32:

  SYSTEM_INFO sysinfo;
  GetSystemInfo(&sysinfo);
  int numCPU = sysinfo.dwNumberOfProcessors;

• Linux, Solaris, AIX, Mac OS X:

  int numCPU = sysconf(_SC_NPROCESSORS_ONLN);

• FreeBSD, MacOS X, NetBSD:

  int numCPU;
  ...
  sysctl(mib, 2, &numCPU, &len, NULL, 0);

Objective-C for Mac OS X and iOS

Objective-C offers a straightforward approach:

NSUInteger processorCount = [[NSProcessInfo processInfo] processorCount];

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