字符串包含问题

// 字符串包含问题。str2中的所有字符，在str1中都出现了。则说str1包含str2.
// 给出str1和str2，判断str1是否包含str2

#include <iostream>
#include <string.h>
#include <assert.h>
using namespace std;


void SetBit(unsigned int *an, int n)
{
	assert(an!=NULL && n>=0 && n<256);
	int n1=n/32;
	int n2=n%32;
	unsigned int &t=*(an+n1);
	t = t | (1<<n2);
}

void ClearBit(unsigned int *an, int n)
{
	assert(an!=NULL && n>=0 && n<256);
	int n1=n/32;
	int n2=n%32;
	unsigned int &t=*(an+n1);
	t = t & ~(1<<n2);
}
int getBit(unsigned int *an, int n)
{
	assert(an!=NULL && n>=0 && n<256);
	int n1=n/32;
	int n2=n%32;
	unsigned int t=*(an+n1);
	int r = (t<<(31-n2))>>31;
	return r;
}

bool isStrIn(const char *str1, const char *str2)
{
	assert(str1!= NULL && str2 != NULL);
	int m=strlen(str1);
	int n=strlen(str2);
	unsigned int bitm[8];
	memset(bitm, 0, sizeof(unsigned int)*8);

	int i;
	for (i=0; i<m; i++)
	{
		SetBit(bitm, (unsigned int)(unsigned char)str1[i]);
	}

	for (i=0;i<n;i++)
	{
		if (getBit(bitm, str2[i]) != 1)
		{
			return false;
		}
	}

	return true;

}

int main()
{
	char str1[]={"I love C++ abcdefg"};
	char str2[]={"abcd"};
	char str3[]={"abcx"};

	cout<<str1<<"  "<< (isStrIn(str1,str2)?"contains  ":"DO NOT Contains  ") <<str2<<endl;
	cout<<endl;

	cout<<str1<<"  "<< (isStrIn(str1,str3)?"contains  ":"DO NOT Contains  ") <<str3<<endl;
	cout<<endl;
	return 0;
}