技術標籤：C/C++c++字串

【問題描述】
將一個16位二進位制數表示成0和1的字元序列，即用一個字元陣列來存放這個二進位制數。在這個類中設定兩個建構函式，一個是傳遞整數引數的，另一個是傳遞字串引數的。因為使用者在建立物件時傳遞的二進位制數，可能是以整數形式給出，也可能是以數字串形式給出，系統應該都能接受。另外有一個型別轉換函式int()，用來將類型別向整型轉換，即將二進位制形式的類物件轉換為整形數。兩個過載運算子“+”，“-”，用來完成兩個二進位制數之間的加減運算。

class binary { //定義二進位制類

char bits[16]; //二進位制字模陣列

public:

binary(char *); //字串引數建構函式

binary(int); //整型引數建構函式

friend binary operator +(binary,binary); //過載“+”，友元函式

friend binary operator -(binary,binary); //過載“-”，友元函式

operator int(); //類型別轉換函式，成員函式

friend ostream & operator <<(ostream &out, binary &b);//過載“<<”，以二進位制形式輸出

void print();//以整型形式輸出

};

主函式設計如下，請勿修改：

int main(){

binary n1=“1011”;

binary n2=int(n1)+15;

binary n3=n1-binary(7);

cout<<n1<<endl;

cout<<n2<<endl;

cout<<n3<<endl;

cout<<int(n2)+5<<endl;

n2=n2-binary(5);

n2.print();

n3=n3+binary(5);

n3.print();

cout<<int(n3)-5<<endl;

return 0;

}

【樣例輸出】

0000000000001011

0000000000011010

0000000000000100

31

21

9

4

程式碼如下

#include<iostream>
#include<string.h>
#include<cmath>
using namespace std;
class binary {
	char bits[16];
public:
	binary(char *s);
	binary(int n);
	friend binary operator+(binary b1, binary b2);
	friend binary operator-(binary b1, binary b2);
	operator int();
	friend ostream & operator<<(ostream &out, binary &b);
	void print();
};
binary::binary(char *s)
{
	int i, size = strlen(s);
	for (i = 0; i < 16 - size; i++)
	{
		bits[i] = '0';
	}
	for (int j = 0; j < size; j++,i++)
	{
		bits[i] = s[j];
	}
}

binary::binary(int n)
{
	int re, i = 0;
	while (n != 0)
	{
		re = n % 2;
		bits[i++] = re + 48;
		n /= 2;
	}
	while (i<16)
	{
		bits[i++] = '0';
	}
	for (int k = 0, j = 15; k < j; k++, j--)
	{
		re = bits[k];
		bits[k] = bits[j];
		bits[j] = re;
	}
}

binary::operator int()
{
	int j = 0, ans = 0;
	for (int i = 15; i >= 0; i--,j++)
	{
		ans += (bits[i] - 48)*pow(2, j);
	}
	return ans;
}

void binary::print()
{
	cout << int(*this) << endl;
}

binary operator+(binary b1, binary b2)
{
	binary temp(int(b1)+int(b2));
	return temp;
}

binary operator-(binary b1, binary b2)
{
	binary temp(int(b1)-int(b2));
	return temp;
}

ostream & operator<<(ostream & out, binary & b)
{
	for (int i = 0; i < 16; i++)
		out << b.bits[i];
	return out;
}

int main()
{
	binary n1 = const_cast<char*>("1011");
	binary n2 = int(n1) + 15;
	binary n3 = n1 - binary(7);
	cout << n1 << endl;
	cout << n2 << endl;
	cout << n3 << endl;
	cout << int(n2) + 5 << endl;
	n2 = n2 - binary(5);
	n2.print();
	n3 = n3 + binary(5);
	n3.print();
	cout << int(n3) - 5 << endl;
	return 0;
}