申请堆空间时出现的错误

116 阅读 0 评论 77 点赞

我是靠谱客的博主热情白开水，这篇文章主要介绍申请堆空间时出现的错误，现在分享给大家，希望可以做个参考。

复制代码

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

struct foo{
	int a;	//4
	char b[6];	//8
	char *p;	//4
	char c[0];
};

#define EXPAND_MEM	15

int main()
{
	printf("size =%un",sizeof(struct foo));
	
	struct foo *pf = (struct foo*)malloc(sizeof(struct foo)+EXPAND_MEM*sizeof(int));

复制代码

1
<span style="white-space:pre">	</span>/* 之前代码

复制代码

1
<span style="white-space:pre">	</span>*<span style="white-space:pre">	</span><span style="font-family: Arial, Helvetica, sans-serif;">struct foo *pf = (struct foo*)malloc(sizeof(struct foo)+EXPAND_MEM);//这样后面赋值的时候就会越界</span><span style="font-family: Arial, Helvetica, sans-serif;">	</span>

复制代码

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
<span style="white-space:pre">	</span>*/
	if(!pf){
		printf("there is not enough memory!n");
		exit(EXIT_FAILURE);
	}
	strcpy(pf->b,"hello");
	printf("pf->b :%s,pf :%pn",pf->b,pf);
	
	int i;
	for(i=0;i<EXPAND_MEM;i++){
		*(pf->c +i)=i;
	}
	#if 1
	printf("pf->b :%s,pf :%pn",pf->b,pf);
	printf("pf->c=[");
	for(i=0;i<EXPAND_MEM;i++){
		printf("%d ",*((pf->c)+i));
	}
	printf("]n");
	#endif

	pf->p = (char *)calloc(EXPAND_MEM,sizeof(char));
	if(!(pf->p)){
		printf("there is not enough memory!n");
		exit(EXIT_FAILURE);
	}
	strcpy(pf->p,"I LOVE Linux");
	printf("pf->p %sn",pf->p);

	free(pf->p);
	free(pf);
	return 0;
}