从一个字符串中删除另一个字符串中出现的字符

#include <stdio.h>

void delete_char(char *a, char *b)
{
if(a==NULL || b==NULL)
return;
char hash_table[256] = {0};//创建简单哈希数组，存储字符串b中每个字符出现的次数
char *p = b;
while(*p != '\0')
hash_table[*p++]++;
char *fast = a;
char *slow = a;
while(*fast != '\0')
{
if(hash_table[*fast]==1)//如果该字符是字符串b中出现的，则指针直接++
{
fast++;
}
else//否则，将其值赋给*slow
{
*slow++ = *fast++;
}
}
*slow = '\0';//别忘了给结尾赋'\0'
}

int main()
{
char a[] = "we are students";
char b[] = "aeiou";
printf("%s中删除%s中出现的字符，结果是:\n",a,b);
delete_char(a,b);
printf("%s\n",a);
return 0;
}