在OSX上以编程方式确定物理内存大小

sysctl hw.memsize

#include<stdio.h>
#include <stdlib.h>
#include <sys/sysctl.h>

int main() {
    uint64_t mem_size;
    size_t len = sizeof(mem_size);
    sysctlbyname("hw.memsize", &mem_size, &len, NULL, 0);
    printf("Physical memory size: %llu bytes\n", mem_size);
    return 0;
}