using System;
namespace test
{
class Program
{
public static int jiecheng(int n)
{
int fac= 1;
for (int i = n; i >= 1; i--)
{
fac *= i;
}
return fac;
}
static void Main(string[] args)
{
double sum= 1;
for (int i=1;i<=10; i++)
{
sum=sum+(double)(1.0/jiecheng(i))+i*i;
Console.WriteLine(sum);
}
Console.ReadLine();
}
}
}
using System;
namespace test
{
class Program
{
static void Main(string[] args)
{
string filename = @"hello world.txt";
int indexDot = filename.LastIndexOf('.');
string extendName = "dat";
filename = filename.Substring(0, indexDot+1);
String[] splitStrings = filename.Split(' ');//Split返回值是字符串数组
filename = string.Join("_", splitStrings);//返回值是字符串
filename = filename + extendName;
Console.WriteLine(filename);
Console.ReadLine();
}
}
}
抽象类的继承
using System;
namespace test
{
public abstract class Father
{
public abstract double Surfacearea();
public abstract double Volume();
}
public class Ball : Father
{
public double r;
public Ball(double r)
{
this.r = r;
}
public override double Surfacearea()
{
return 4 * Math.PI * r * r;
}
public override double Volume()
{
return 4.0/3.0 * Math.PI * r * r*r;
}
}
public class Cylinder : Father
{
public double r;
public double h;
public Cylinder(double r, double h)
{
this.r = r;
this.h = h;
}
public override double Surfacearea()
{
return 2 * Math.PI * r * (r+h);
}
public override double Volume()
{
return Math.PI * r * r * h;
}
}
public class Cone : Father
{
public double r;
public double h;
public Cone(double r, double h)
{
this.r = r;
this.h = h;
}
public override double Surfacearea()
{
return Math.PI * r * (r + Math.Sqrt(h