zy20090225.txt

钱能C++程序设计教程（第二版）部分习题答案

1.9.1
#include<iostream>
#include<string>
#include<fstream>
using namespace std;
int main ()
{
	string st="I am a student";
	ofstream out("a.txt");
    out<<st<<endl;
	ifstream in("a.txt");
	for(string str; getline(in,str);)
		cout<<str<<endl;
} 
1.9.2
#include<iostream>
#include<cmath>
using namespace std;
int main ()
{
	int a,b,c;
	for(a=1;a<=7;a++)
	{
		for(b=1;b<=abs(4-a);b++)
			cout<<" ";
		if(a<=4)
			for(c=1;c<=2*a-1;c++)
				cout<<"*";
		else
			for(c=1;c<=15-2*a;c++)
				cout<<"*";
	    cout<<"\n";
	}
	return 0;

}
1.9.1
#include<iostream>
using namespace std;
int main ()
{
	cout<<"I am a student"<<endl;
	return 0;
}
2.9.2
#include<iostream>
using namespace std;
int main ()
{
	int b=0;
	long a=1,sum=0;
	for(b=0;b<12;b++)
	{	
		a=a*(b+1);
	    sum=sum+a;    
	}
	cout<<sum<<endl;
	return 0;
}
2.9.1
#include<iostream>
#include<cmath>
using namespace std;
int main ()
{
	int a,b=-1,c,d=0,e,f;
	cin<<a;
	b=(-1)*b;
	for(d=0,,d++)
	{
	  c=c*(d+1)
	  return 0;
}
2.9.9
#include<iostream>
using namespace std;
int func(int n )
{
	int sum;
	if(n<4)
		sum=1;
	else
		sum=func(n-1)+func(n-3);
	return sum;
}
int main ()
{
	int n;
	cin>>n;
	cout<<func(n)<<endl;
	return 0;

}