使用malloc对于结构的块 [英] using malloc for block of structs

问题描述

我试图分配的内存块，并存储结构的列表，而无需使用多个mallocs为每...这只是一个普通的例子，我没有原来的code我正在同早些时候，但这是一般的想法，但我的问题是，当我的code的其他部分InitPoints（）函数调用之后执行的，我是越来越堆损坏。我不知道我的code的一部分是非法的，但我怀疑这是在为InitPoints环路（）函数。我试图用这个作为表，那么我可以创建定义大小的附加表，如果我用完了内存和它们链接在一起......所以有点像一个动态扩展数组，如果让任何意义。

  typedef结构{铽
   POINT点;
   POINT *接下来的;
 }表;typedef结构{铂
   INT X;
   诠释Ÿ;
}点;POINT * mypoints;诠释主（）{
   INT大小= 10;
   INT I = 0;
   mypoints = InitPoints（大小）;   对于（i = 0; I＆LT;大小;我++）
   {
      的printf（mypoint内容[％d] =（％D，％D）\\ n，我，mypoints-＆GT; X，mypoints-＆GT; Y）;
      mypoints = mypoints +的sizeof（POINT）;
   }
  //其他一些code ...
  //即的CreateThread（....）   返回0;
}POINT * I​​nitPoints（INT大小）
{
   POINT * tmp目录;
   POINT *原稿;
   INT A = 10;
   INT B = 1000;
   原稿=（POINT *）malloc的（的sizeof（POINT）*大小）;
   如果（原稿== NULL）
      返回NULL;   TMP =原稿;
   对于（i = 0; I＆LT;大小;我++）
   {
      tmp-＆GT; X = A ++;
      tmp-＆GT; Y = B ++;
      TMP = TMP +的sizeof（POINT）;
   }
返回原稿;
}
 

解决方案

这是错误的：

  mypoints = mypoints +的sizeof（POINT）;
 

您应该检查C.指针运算只需使用：

  mypoints + = 1; / *或类似的东西* /
 

（有你InitPoints功能类似的问题）

这里有一个referemce：

http://www.eskimo.com/~scs/cclass/笔记/ sx10b.html

I am trying to allocate a block of memory, and store a list of structures without using multiple mallocs for each... this is just a generic example, I don't have the original code I was working with earlier, but this is the general idea, but my problem was that I was getting heap corruption when other parts of my code executed after the InitPoints() function call. I don't know what part of my code is illegal, but I suspect it is in the for loop of the InitPoints() function. I am trying to use this as table, then I can create additional tables of defined size if I ran out of memory and link them together... so kind of like a dynamic expanding array if that makes any sense.

typedef struct Tb{
   POINT points;
   POINT *next;
 } TABLE;

typedef struct Pt{
   int x;
   int y;
}POINT;

POINT *mypoints;

int main() {
   int size = 10;
   int i = 0;
   mypoints = InitPoints(size);

   for(i=0; i < size; i++)
   {
      printf("mypoint [%d] = (%d,%d)\n",i, mypoints->x, mypoints->y);
      mypoints = mypoints + sizeof(POINT);
   }
  // some other code...
  // i.e. createThread(....)

   return 0;
}

POINT* InitPoints(int size)
{
   POINT *tmp;
   POINT *orig;
   int a = 10;
   int b = 1000;
   orig = (POINT*) malloc (sizeof(POINT) * size);
   if(orig == NULL)
      return NULL;

   tmp = orig;
   for (i = 0; i < size; i++)
   {
      tmp->x = a++;
      tmp->y = b++;
      tmp = tmp + sizeof(POINT);
   }
return orig;
} 

解决方案

This is wrong:

mypoints = mypoints + sizeof(POINT); 

You should review pointer arithmetic in C. Just use:

mypoints += 1; /* or something similar */

(There is a similar problem in your InitPoints function)

Here's one referemce:

http://www.eskimo.com/~scs/cclass/notes/sx10b.html

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