钱能C++教材习题答案三

   /2005-05-08

 

//************************
//*        4_9(3).chh    *
//*                      *
//************************
# include <iostream.h>
# include <math.h>
# include <iomanip.h>
void main()
{
        cout<<setw(6)<<setiosflags(ios::right)<<"*";
        int i;
        for (i=1;i<10;i++)
        {
                cout<<setw(6)<<setiosflags(ios::right)<<i;
        }
cout<<endl;
        for (i=1;i<11;i++)
        {
                cout<<setw(6)<<setiosflags(ios::right)<<".......";
        }
cout<<endl;

        for (i=1;i<10;i++)
        {
                cout<<setw(6)<<setiosflags(ios::right)<<i;
                                int j;
                for (j=1;j<i;j++)
                {
                        cout<<setw(6)<<setiosflags(ios::right)<<" ";
                }
                for (j=i;j<10;j++)
                {
                        cout<<setw(6)<<setiosflags(ios::right)<<i*j;
                }

                cout<<endl;
        }
}

//************************
//*        4_10.chh      *
//*                      *
//************************
# include <iostream.h>
# include <math.h>
# include <iomanip.h>

int total(int a);
void main()
{
        int n,m;
        cout<<"please input years:"<<endl;
        cin>>n;
        m=total(n);
        cout<<"the total of cows:"<<m<<endl;
}
int total(int a)
{
        int b=0;
        int i;
        i=a/4;
        b=int(pow(2,i));
        return b;
}

第五章

//************************
//*        5_1.cpp       *
//************************
# include <iostream.h>
# include <math.h>
# include <iomanip.h>
int isprime(long n);
void main()
{
        long a,b,l=0;
        cout<<"please input two numbers:/n";
        cin>>a>>b;
        cout<<"primes from "<<a<<" to "<<b<<"is:/n";
        if(a%2==0)
                a++;
        for(long m=a;m<=b;m+=2)
        {
                if(isprime(m))
                {
                        if(l++%10==0)
                                cout<<endl;
                        cout<<setw(5)<<m;
                }
        }
        cout<<endl;
}
int isprime(long n)
{
        //int sqrtn=int(sqrt(n));
        int i,j=0;
        for(i=2;i<n/*sqrtn*/;i++)
        {
                if(n%i==0)
                {
                        j=0;
                        break;
                }
        j=1;
        }
        return j;
}
//************************
//*        5_2.cpp       *
//*    计算定积分        *
//************************
# include <iostream.h>
# include <math.h>
# include <iomanip.h>
double f(double);
double integral(double,double);
void main()
{
        double m,n,c;
        cout<<"please input two point:"<<endl;
        cin>>m>>n;
        c=integral(m,n);
cout<<endl<<"the integral of f(x) from"
        <<m<<" to "<<n<<"is /n"
        <<setiosflags(ios::fixed)
        <<setprecision(8)
        <<setw(10)<<c<<endl;
}
double integral(double a,double b)
{
int n=1;
double h,Tn,T2n,In,I2n;
const double eps=1e-8;
h=b-a;
T2n=I2n=h*(f(a)+f(b))/2;
In=0;
while(fabs(I2n-In)>=eps)
{
        Tn=T2n;
        In=I2n;

       double sigma=0.0;
        for (int k=0;k<n;k++)
        {
                double x=a+(k+0.5)*h;
                sigma+=f(x);
        }
        T2n=(Tn+h*sigma)/2.0;
        I2n=(4*T2n-Tn)/3.0;
        n*=2;
        h/=2;
}
return I2n;
}
double f(double x)
{
        return exp(x)/(1+x*x);
}

//************************
//*        5_3.chh       *
//*                      *
//************************
# include <iostream.h>
# include <math.h>
# include <iomanip.h>
void p1();
void p2();
void p3();
void main()
{
        int a;
        cout<<"please input print sty(1-all,2-down,3-up):"<<endl;
        cin>>a;
        cout<<endl;
        switch(a)
        {
        case 1:p1();break;
        case 2:p2();break;
        case 3:p3();break;
        }
}
void p1()
{
        cout<<setw(6)<<setiosflags(ios::right)<<"*";
        int i;
        for (i=1;i<10;i++)
        {
                cout<<setw(6)<<setiosflags(ios::right)<<i;
        }
cout<<endl;
        for (i=1;i<11;i++)
        {
                cout<<setw(6)<<setiosflags(ios::right)<<".......";
        }
cout<<endl;
        for (i=1;i<10;i++)
        {
                cout<<setw(6)<<setiosflags(ios::right)<<i;
                int j;
                for (j=1;j<10;j++)
                {
                        cout<<setw(6)<<setiosflags(ios::right)<<i*j;
                }
                cout<<endl;
        }
}
void p2()
{
        cout<<setw(6)<<setiosflags(ios::right)<<"*";
        int i;
        for (i=1;i<10;i++)
        {
                cout<<setw(6)<<setiosflags(ios::right)<<i;
        }
cout<<endl;
        for (i=1;i<11;i++)
        {
                cout<<setw(6)<<setiosflags(ios::right)<<".......";
        }
cout<<endl;
        for (i=1;i<10;i++)
        {
                cout<<setw(6)<<setiosflags(ios::right)<<i;
                int j;
                for (j=1;j<i+1;j++)
                {
                        cout<<setw(6)<<setiosflags(ios::right)<<i*j;
                }
                cout<<endl;
        }
        return;
}
void p3()
{
        cout<<setw(6)<<setiosflags(ios::right)<<"*";
        int i;
        for (i=1;i<10;i++)
        {
                cout<<setw(6)<<setiosflags(ios::right)<<i;
        }
cout<<endl;
        for (i=1;i<11;i++)
        {
                cout<<setw(6)<<setiosflags(ios::right)<<".......";
        }
cout<<endl;
        for (i=1;i<10;i++)
        {
                cout<<setw(6)<<setiosflags(ios::right)<<i;
                int j;
                for (j=1;j<i;j++)
                {
                        cout<<setw(6)<<setiosflags(ios::right)<<" ";
                }
                for (j=i;j<10;j++)
                {
                        cout<<setw(6)<<setiosflags(ios::right)<<i*j;
                }

               cout<<endl;
        }
        return;
}

//************************
//*        5_4           *
//*                      *
//************************
Main--x=5,y=1,n=1
Func--x=6,y=21,n=11
Main--x=5,y=1,n=11
Func--x=8,y=21,n=31
//************************
//*        5_5.chh       *
//*                      *
//************************
# include <iostream.h>
# include <math.h>
# include <iomanip.h>
int fib(int);
void main()
{
        int n;
        int m;
        cin>>n;
        m=fib(n);
        cout<<"fib("<<n<<""<<"="<<m<<endl;
}
int fib(int a)
{
        if(a>2)
        {
                int tp1=1;
                int tp2=1;
                int temp=0;
                int b;
                for(b=3;b<(a+1);b++)
                {                       
                        temp=tp1+tp2;
                        tp1=tp2;
                        tp2=temp;
                }
                return tp2;
        }
        else return 1;
}
//************************
//*        5_6.chh       *
//*                      *
//************************
# include <iostream.h>
# include <math.h>
# include <iomanip.h>
double poly(int,double);
void main()
{
        int n;
        double x;
        double m;
        cout<<"please input n and x"<<endl;
        cin>>n>>x;
        m=poly(n,x);
        cout<<"poly("<<n<<","<<x<<""<<"="<<m<<endl;
}
double poly(int a,double b)
{
        if(a>1)
        {
                return ((2*a-1)*b*poly((a-1),b)-(a-1)*poly((a-2),b))/2;
        }
        else
        {
                if (a=1)
                        return b;
                else
                        return 1;
        }
}


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