C#:静态字段和静态方法的学习

最近开始学习C#编程：静态字段和静态方法的学习，windows Form 设计如图1，输入原库存量，单价，销售数量，计算出，现库存量和销售额



　　　　　　　　　　　　　　　　　　　　　　　　　图 1
代码实现如下,Form1和Form2功能相同，只不过在，一个类中调用另一个类的静态字段数据时，
　　1）通过静态方法返回需要的字段数据，需要建立返回静态方法
　　2）通过类名直接应用静态字段数据（前提是字段是public的），不需要建返回静态字段方法

通过静态方法返回需要的字段数据：
namespace crashRegister
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
int st;
int inYanKuCun = Convert.ToInt32(textBox1.Text.Trim());
int inCost = Convert.ToInt32(textBox2.Text.Trim());
int inXianKuCun = Convert.ToInt32(textBox3.Text.Trim());
Among a= new Among(inYanKuCun,inCost);
a.MakeIt(inXianKuCun,out st);
textBox4.Text = st.ToString();
textBox5.Text = Among.ChuanZhi().ToString();

}

private void button2_Click(object sender, EventArgs e)
{
textBox1.Text = textBox2.Text = textBox3.Text = textBox4.Text = textBox5.Text = "";
}
}
public class Among
{
int numYanKuCun;
int numCost;
static double xiaoShouE;
public  Among(int m,int n)
{
this.numYanKuCun = m;
this.numCost=n;
}
static Among()
{
xiaoShouE=0.0;
}
public void MakeIt(int num,out int stock)
{
numYanKuCun -= num;
xiaoShouE=numCost*numYanKuCun;
stock=numYanKuCun;

}
static public double ChuanZhi()
{
return xiaoShouE;
}
}
}

通过类名访问静态字段的数据：
1 namespace crashRegister
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
int st;
int inYanKuCun = Convert.ToInt32(textBox1.Text.Trim());  //在textBox1中输入原库存数量赋值给inYanKuCun.
int inCost = Convert.ToInt32(textBox2.Text.Trim());　　　 //在textBox2中输入单价给inCost;
int inXianKuCun = Convert.ToInt32(textBox3.Text.Trim()); //在textBox3中输入销售数量给inXianKuCun.
Among a= new Among(inYanKuCun,inCost);
a.MakeIt(inXianKuCun,out st);
textBox4.Text = st.ToString();
textBox5.Text = Among.xiaoShouE.ToString();

}

private void button2_Click(object sender, EventArgs e)
{
textBox1.Text = textBox2.Text = textBox3.Text = textBox4.Text = textBox5.Text = "";
}
}
public class Among
{
int numYanKuCun;
int numCost;
public static double xiaoShouE;
public  Among(int m,int n)
{
this.numYanKuCun = m;
this.numCost=n;
}

public void MakeIt(int num,out int stock)
{
numYanKuCun -= num;
xiaoShouE=numCost*numYanKuCun;
stock=numYanKuCun;

}

}
}