How to Get Available System Memory in C /g ?

Getting Available Memory in C /g

In modern applications, it is crucial to optimize memory usage to enhance performance and stability. To effectively allocate buffers according to available memory, developers need to know how to retrieve this information. This article explores platform-independent methods for obtaining available memory in C /g .

UNIX-Like Operating Systems

UNIX-like systems provide the sysconf function to access system configuration information. By passing _SC_PHYS_PAGES and _SC_PAGE_SIZE, developers can retrieve the number of physical pages and the page size, respectively. Multiplying these values together provides the total system memory.

#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 provides information about the system's memory usage. By setting the dwLength member to the size of the MEMORYSTATUSEX structure and calling the function, developers can access the ullTotalPhys member, which represents the total physical memory.

#include <windows.h>

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

Platform Independence

To make the code platform-independent, developers can use #ifdef directives to define system-specific versions of the getTotalSystemMemory function. For example, the following code combines both methods:

#ifdef __UNIX__
unsigned long long getTotalSystemMemory()
{
    return ::getTotalSystemMemory();
}
#elif defined(_WIN32) // Windows
unsigned long long getTotalSystemMemory()
{
    return ::getTotalSystemMemory();
}
#else
#error "Unsupported platform"
#endif

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