练习.txt

钱能主编 C++程序设计教程（第一版） 该书习题的答案代码

19.1
# include <iostream.h>
# include <fstream.h>
void main()
{
        ifstream fin("e:\\c++\\test.txt",ios::nocreate);
        if(fin.fail())
        {
                cerr<<"error open files!"<<endl;
                return;
        }

        int i=0;
		char letter;
        letter=fin.get();

        while (!fin.eof())
        {
			if(letter=='\n')
			{
				//cout<<"Enter be encounted."<<endl;
				i++;
				letter=fin.get();
			}
			else
			{
				letter=fin.get();
			}
        }
		i++;
        cout<<"lines:"<<i<<endl;
}

19.3
#include <iostream.h>
#include <strstrea.h>
#include <iomanip.h>

void main()
{
	char* string="1 2 3 4 5 6 7 8 9";
	int i;

	istrstream inf(string,0);

	while(!inf.eof())
	{
		inf>>i;
		cout<<setw(2)<<i;
	}
	cout<<endl<<"end of program."<<endl;
}

19.4
#include <iostream.h>
#include <iomanip.h>

void main()
{
	char ch='A';
	for(;ch<='Z';ch++)
	{
		cout<<ch<<":";
		cout<<"0x"<<hex<<setiosflags(ios::uppercase)<<(int)ch<<endl;
	}
	cout<<"end of program."<<endl;
}

19.5
//可以通过编译，但是运行时出错。
# include <fstream.h>
# include <iostream.h>
class person
{
public:
        person();
        person(char * a,char * b=0,char* c=0,char* d=0,char * e=0)
        {
                name=a;
                dep=b;
                tel1=c;
                street=d;
                tel2=e;
        }
        void display(ostream & out)
        {
                out<<"Name:"<<name<<"Dept:"<<dep<<"tel of office:"<<tel1
                        <<"address:"<<street<<"tel of home:"<<tel2<<endl;
        }
protected:
        char * name;
        char * dep;
        char * tel1;
        char * street;
        char * tel2;
};
ostream & operator<<(ostream & m,person & n)
{
        n.display(m);
        return m;
}
void main()
{
		fstream fdev("e:\\c++\\test2.txt",ios::in|ios::out|ios::ate,filebuf::sh_none);
        char * j=0;
        char * k=0;
        char * x=0;
        char * y=0;
        char * z=0;
        cin>>j>>k>>x>>y>>z;
        cout<<j<<k<<x<<y<<z;
        while(j!=0)
        {
                fdev<<j<<" "<<k<<" "<<x<<" "<<y<<" "<<z<<"/n";
                cin>>j>>k>>x>>y>>z;
        }
        cout<<endl;
        
		//ifstream fd("e:\\c++\\test2.txt");
		
		while(!fdev.eof())
        {
                char * a=0;
                char * b=0;
                char * c=0;
                char * d=0;
                char * e=0;
                fdev>>a>>b>>c>>d>>e;
                person p=person(a,b,c,d,e);
                cout<<p;
        }
        cout<<endl;
}