不会啊! 想了好久也不会啊!因为中间有东西我没学

程序一:
#include <iostream.h>
void main()
{
int i,j,k;
for(i=1;i<=5;i++)
{
for(j=1;j<=7-i;j++)
cout<<' ';
for(k=1;k<=2*i-1;k++)
if(k==1||k==2*i-1)
cout<<'*';
else
cout<<' ';
cout<<endl;
}
for(i=1;i<=4;i++)
{
for(j=1;j<=i+2;j++)
cout<<' ';
for(k=1;k<=9-2*i;k++)
if(k==1||k==9-2*i)
cout<<'*';
else
cout<<' ';
cout<<endl;
}
cout<<endl;
}



程序二:
#include <iostream.h>
void main()
{int i,a[10];
float j=0;
int x,y=a[0];
for(i=0;i<10;i++)
{cout<<"请输入成绩： ";
cin>>a[i];
j=j+a[i];
}j=j/10;
cout<<"平均成绩： "<<j<<endl;

cout<<"最高分: ";
for(i=0;i<10;i++)
if(x<a[i]) x=a[i];
cout<<x<<endl;
{cout<<"最低分: ";
for(i=0;i<10;i++)
if(y>a[i]) y=a[i];
cout<<a[i]<<endl;}
for(i=0;i<10;i++)
cout<<"输出成绩: "<<a[i]<<' '<<endl;}

程序三:#include <iostream.h>
const int x=3;
void main()
{
int m[x][x];
for(int i=0;i<x;++i)
{
for(int j=0;j<x;++j)
m[i][j]=0;
}
int r=0,c=x/2;
m[r][c]=1;
for(int num=2;num<=x*x;++num)
{
int cpy_r=r,cpy_c=c;
r-1<0?r=x-1:--r;
c-1<0?c=x-1:--c;
if (m[r][c] != 0)
{
cpy_r+1>x-1?r=0:r=cpy_r+1;
c=cpy_c;
}
m[r][c]=num;
}
for(i=0;i<x;++i)
{
for (int j=0;j<x;++j)
{
if (m[i][j]<10)
cout<<" ";
cout<<m[i][j]<<" ";
}
cout<<endl<<endl;
}
}

程序四:
#include <iostream.h>
#include <math.h>
class Quadratic
{
double a,b,c;
public:
Quadratic(){a=b=c=0;}
Quadratic(double aa,double bb,double cc);
Quadratic operator+(Quadratic &x);
Quadratic operator-(Quadratic &x);
double Compute(double x);
int Root(double &r1,double &r2);
void Print();
};
Quadratic Quadratic::operator+(Quadratic &x)
{
Quadratic m;
m.a=a+x.a;
m.b=b+x.b;
m.c=c+x.c;
return m;
}
Quadratic Quadratic::operator-(Quadratic &x)
{
Quadratic n;
n.a=a-x.a;
n.b=b-x.b;
n.c=c-x.c;
return n;
}
double Quadratic::Compute(double x)
{

return a*x*x+b*x+c;
}
int Quadratic::Root(double &r1,double &r2)
{
if(a==0)
{
cout<<"不是一元二次函数"<<endl; return -1;
}
if(b*b-4*a*c==0)
{
r1=r2=(-b)/2*a; return 1;
}
if(b*b-4*a*c<0)
{
cout<<"无实根"<<endl; return 0;
}
else
{ r1=(-b)+sqrt(b*b-4*a*c)/(2*a);
r2=(-b)-sqrt(b*b+4*a*c)/(2*a);
return 1;
}
}
void Quadratic::Print()
{
if(b<0 && c<0)
{
cout<<a<<"x**2"<<b<<"x"<<c<<endl;
}
if(b<0 && c>0)
{
cout<<a<<"x**2"<<b<<"x"<<"+"<<c<<endl;
}
if(b>0 && c<0)
{
cout<<a<<"x**2"<<"+"<<b<<"x"<<c<<endl;
}

}
Quadratic::Quadratic(double aa,double bb,double cc)
{
a=aa;
b=bb;
c=cc;
}
void main()
{
double a,b,c,x;
double r1,r2;
cout<<"请输入方程三个系数a,b,c的值:"<<endl;
cout<<"a= ";cin>>a;
cout<<"b= ";cin>>b;
cout<<"c= ";cin>>c;
Quadratic p1(a,b,c);
cout<<"该函数是: "<<endl;
p1.Print();
cout<<"该函数为零的两个根是: "<<endl;
p1.Root(r1,r2);
cout<<r1<<" "<<r2<<endl;
cout<<"请输入一个X值: "<<endl;
cin>>x;
cout<<"当输入X的值为: "<<x<<"时该函数的值为: "<<endl;
p1.Compute(x);
cout<<p1.Compute(x)<<endl;
cout<<endl;
}