数字在排序数组中出现的次数

int CountNumInSortArray(int a[],int n,int key)
{
	if(a==NULL||n<=0)
		throw exception("Invalid Input");
	int i=0,j=n-1;
	bool isFind=false;
	while(i<=j)
	{
		int m=i+(j-i)/2;
		if(a[m]<key)
			i=m+1;
		else if(a[m]>key)j=m-1;
		else
		{
			j=m;
			isFind=true;
			if(i==j)
				break;
		}
	}
	cout<<i<<endl;
	int start;
	if(isFind)
		start=i;
	else
		return -1;
	j=n-1;
	while(i<j-1)
	{
		int m=i+(j-i)/2;
		if(a[m]<key)
			i=m+1;
		else if(a[m]>key)j=m-1;
		else
		{
			i=m;
		}
	}
	int end;

	if(i+1==j&&a[i]==a[j])
	{
		end=j;
	}
	else
		end =i;
	return end-start+1;
}

　　

void main()
{
	
	int a[]={1,2,3,3,3,3,4,5};

	try
	{
		int num=CountNumInSortArray(a,8,5);
		if(num==-1)
			cout<<"Can not find!"<<endl;
		else
			cout<<num<<endl;
	}
	catch(exception e)
	{
		cout<<e.what()<<endl;
	}
	system("pause");
}