珠心算：目前和为9以内加减法；最多随机7个数字，从第二个数字开始，随机数加前面的数字和不超过9， 差不能小于0； 据此规则得： 0-sum<=a <= 9-sum; 得知待填入数字a的范围。
通过for 遍历， 获得处在这个区间的数字在数组中的index， 以这个index做为 random.next（min,max） 中min 和max的值。 进而获了符合要求的随机数字。
最后在timer中使用： button2.performce； 可以定时的执行button2中的代码。
Winform下，代码：
Class1.cs中代码：
using System;using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks; namespace 珠心算
{
public class myclass
{
Random randomnumber = new Random();
public int[] num = { -9,-8,-7,-6,-5,-4,-3,-2,-1,1,2,3,4,5,6,7,8,9};
int[] num2 = { 1,2,3,4,5,6,7,8,9 };
string[] symbol = { "+", "-" };
public int getrandomnumber(int a,int b)
{
return num[randomnumber.Next(a, b)];
} public int getrandomnumberU()
{
return num2[randomnumber.Next(0, 9)];
}
public string getrandomsymbol()
{
return symbol[randomnumber.Next(0,2)];
}
}
} --------------------------------------------------------------------------------- Form1.cs 中代码如下： using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms; namespace 珠心算
{
public partial class Form1 : Form
{
delegate void MyDel();
MyDel myDel;
int[] numArr1 = {-9,-8,-7,-6,-5,-4,-3,-2,-1,1,2,3,4,5,6,7,8,9 };
public Form1()
{
InitializeComponent();
} private void Form1_Load(object sender, EventArgs e)
{
string[] gamestle = { "2数加减", "3数加减", "4数加减", "5数加减", "6数加减", "7数加减" };
foreach (var item in gamestle)
{
comboBox1.Items.Add(item);
} comboBox1.SelectedIndex = 5;
} private void textBox1_TextChanged(object sender, EventArgs e)
{ } //button ------------------------------------------------------------------------------------------
TextBox tx1 = new TextBox();
TextBox tx2 = new TextBox();
myclass m = new myclass();
private void button1_Click(object sender, EventArgs e)
{
label7.Visible = true;
} int sum = 0;
int lowerlimt = 0;
int upperlimit = 0; private void button2_Click(object sender, EventArgs e)
{
label7.Visible = false;
for (int n = 1; n < groupBox1.Controls.Count+1; n++) //每次点按钮，清空所有数字
{
tx2 = (TextBox)this.Controls.Find("textBox" + n.ToString(), true)[0];
tx2.Text ="0";
} textBox1.Text = m.getrandomnumberU().ToString();//textbox1 先放置随机的无符号数值； for (int i = 2; i < comboBox1.SelectedIndex+3; i++)//后面的textbox，依据条件，逐个放置数字；
{
tx1 = (TextBox)this.Controls.Find("textBox" + i.ToString(), true)[0];
// MessageBox.Show("总循环号 i = " + i);
sum = 0;
for (int b = 1; b < comboBox1.SelectedIndex+3; b++) //每一次循环，计算出现有的总和
{
tx2 = (TextBox)this.Controls.Find("textBox" + b.ToString(), true)[0];
sum = sum + int.Parse(tx2.Text);
}
// MessageBox.Show("计算sum 的循环号 b =计算出的和是= "+sum); //获取lowerlimit
for (int a = 0; a < numArr1.Length; a++) //获得总数值之后；依条件，来计算在数组中，哪些索引号之间的数字可以用于下一个textbox的显示
{
if (numArr1[a]==0-sum)// 需研究，最初 ==0-sum+1 为什么总是出现 lower > upper的情况；需要
{
lowerlimt = a;
// MessageBox.Show("lowerlimt is " + a);
}
} //获取upperLimit
for (int c = 0; c < numArr1.Length; c++)
{
if (numArr1[c] == 9 - sum)
{
upperlimit = c;
// MessageBox.Show("upper limit is " + c);
}
} tx1.Text = m.getrandomnumber(lowerlimt+1, upperlimit+1).ToString("+#;-#;0");
// MessageBox.Show("新增随机数i=" + i + "值在tx1中是" + tx1.Text); sum = 0;
for (int b = 1; b < comboBox1.SelectedIndex+3; b++) //每一次循环，计算出现有的总数
{
tx2 = (TextBox)this.Controls.Find("textBox" + b.ToString(), true)[0];
sum = sum + int.Parse(tx2.Text);
label7.Text = sum.ToString();
// MessageBox.Show("计算sum 的循环号 b = " + b+"计算出的和是= "+sum); } lowerlimt = 0;
upperlimit = 0;
}
} private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
for (int n = 1; n < groupBox1.Controls.Count+1; n++) //每次点按钮，清空所有数字
{
tx2 = (TextBox)this.Controls.Find("textBox" + n.ToString(), true)[0];
tx2.Text = "0"; if (n>comboBox1.SelectedIndex+2)
{
tx2.Visible = false;
}
else
{
tx2.Visible = true;
}
}
} private void label7_Click(object sender, EventArgs e)
{ } private void timer1_Tick(object sender, EventArgs e)
{
timer1.Enabled = true;
timer1.Interval = 1000;
button2.PerformClick(); } private void checkBox1_CheckedChanged(object sender, EventArgs e)
{
if (checkBox1.Checked == true)
{
timer1.Start();
}
else
{
timer1.Stop();
}
}
}
} ------------------------------------- winform设计界面：