How Can I Determine Available System Memory in C Across Different Platforms?

Determining Available Memory in C

When dealing with memory-intensive applications, it is crucial to allocate buffers according to the available memory. This ensures that processing can proceed without exceeding memory limits and causing system instability. In a cross-platform environment, it is necessary to employ a platform-independent method to obtain available memory information.

Unix-Like Systems

Unix-like operating systems provide the sysconf function, which allows us to retrieve system configuration information. To obtain the total system memory, we can use:

#include <unistd.h>

unsigned long long getTotalSystemMemory()
{
    long pages = sysconf(_SC_PHYS_PAGES);
    long page_size = sysconf(_SC_PAGE_SIZE);
    return pages * page_size;
}

Windows

On Windows, the GlobalMemoryStatusEx function can be used to retrieve memory information. The following code demonstrates how to use it:

#include <windows.h>

unsigned long long getTotalSystemMemory()
{
    MEMORYSTATUSEX status;
    status.dwLength = sizeof(status);
    GlobalMemoryStatusEx(&status);
    return status.ullTotalPhys;
}

Cross-Platform Implementation

To create a cross-platform solution, we can use conditional compilation to select the appropriate function based on the operating system:

#ifdef __unix__
unsigned long long getTotalSystemMemory() { return sysconf(_SC_PHYS_PAGES) * sysconf(_SC_PAGE_SIZE); }
#elif _WIN32
unsigned long long getTotalSystemMemory()
{
    MEMORYSTATUSEX status;
    status.dwLength = sizeof(status);
    GlobalMemoryStatusEx(&status);
    return status.ullTotalPhys;
}
#endif

This will provide a consistent way to retrieve the available memory for your application on different operating systems.

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