C++ 测试系统允许分配的最大堆内存

Posted 2020-07-10

#include<stdio.h>

#include<stdlib.h>

unsigned int maxnum = 0;

int main()
{

  unsigned int blocksize[3]={1024*1024,1024,1};
  int i,count;
  for (i = 0; i < 3; i++)
  {
    for(count=1;;count++)
    {
      void* pmalloc = malloc(maxnum + blocksize[i] * count );
      if (pmalloc)
      {
        maxnum = maxnum + blocksize[i] * count;
        free(pmalloc);  //为什么要在这里释放？？？ pmalloc是空指针了
      }
      else
      {
        //free(pmalloc);  //为什么不在这里释放内存？？？
        break;
      }
    }
  }
  printf("maxium malloc size is %u bytes\n",maxnum);
  return 0;

}