C语言内存申请与使用

#include<stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/time.h>
#include <sys/resource.h>

typedef struct v_block *p_block;
struct v_block{

        p_block next;
        int free;
        char *key;
        char *value;
        char data[];

};

int main() {
p_block pmem=(p_block)malloc(40);
pmem->next=0;
pmem->free=0;
pmem->key=pmem->data;
int i;
char *s="one";
for(i=0;i<4;i++) {
        *(pmem->key+i)=s[i];
}
pmem->value=pmem->key+4;
char *va="this is a value";
for(i=0;i<15;i++) {
        *(pmem->value+i)=va[i];
}

printf("%s ",pmem->value);
printf("%s ",pmem->key);
return 0;
}