4elist1720.cpp

《21天学通C＋＋》附盘的原代码。书上的每个例子在这里都有相应的C语言程序。

//Listing 17.20 Using Command-line Arguments
#include <fstream>
#include <iostream>
using namespace std;

class Animal
{
public:
	Animal(int weight,long days):itsWeight(weight),DaysAlive(days){}
	~Animal(){}

	int GetWeight()const { return itsWeight; }
	void SetWeight(int weight) { itsWeight = weight; }

	long GetDaysAlive()const { return  DaysAlive; }
	void SetDaysAlive(long days) { DaysAlive = days; }

private:
	int itsWeight;
	long DaysAlive;
};

int main(int argc, char *argv[])   // returns 1 on error
{
	if (argc != 2)
	{
		cout << "Usage: " << argv[0] << " <filename>" << endl;
		return(1);
	}

	ofstream fout(argv[1],ios::binary);
	if (!fout)
	{
		cout << "Unable to open " << argv[1] << " for writing.\n";
		return(1);
	}

	Animal Bear(50,100);
	fout.write((char*) &Bear,sizeof Bear);

	fout.close();

	ifstream fin(argv[1],ios::binary);
	if (!fin)
	{
		cout << "Unable to open " << argv[1] << " for reading.\n";
		return(1);
	}

	Animal BearTwo(1,1);

	cout << "BearTwo weight: " << BearTwo.GetWeight() << endl;
	cout << "BearTwo days: " << BearTwo.GetDaysAlive() << endl;

	fin.read((char*) &BearTwo, sizeof BearTwo);

	cout << "BearTwo weight: " << BearTwo.GetWeight() << endl;
	cout << "BearTwo days: " << BearTwo.GetDaysAlive() << endl;
	fin.close();
	return 0;
}