新手学编写游戏属性计算器问题！！急！
private void Upgrade()
{
int grade=int.Parse(this.txtGrade.Text);
for (int i = 0; i <= grade; i++) //级别每增加1级增加的属性
{
double number,corporeity, alchemy, strength, stamina, celerity;
number = double.Parse(this.txtNumber.Text); //可用属性
corporeity = double.Parse(this.txtCorporeity.Text); //体质
alchemy = double.Parse(this.txtAlchemy.Text); //魔力
strength = double.Parse(this.txtStrength.Text); //力量
stamina = double.Parse(this.txtStamina.Text); //耐力
celerity = double.Parse(this.txtCelerity.Text); //敏捷
number+=5;
corporeity++;
alchemy++;
strength++;
stamina++;
celerity++;
this.txtNumber.Text = number.ToString(); //升级后可用属性
this.txtCorporeity.Text = corporeity.ToString();　　//升级后体质
this.txtAlchemy.Text = alchemy.ToString();　　　　　//升级后魔力

this.txtStrength.Text = strength.ToString(); //升级后力量
this.txtStamina.Text = stamina.ToString(); //升级后耐力
this.txtCelerity.Text = celerity.ToString(); //升级后敏捷
}

在一个textBox事件里调用这个方法出错
未处理FormatException
输入字符串的格式不正确
number = double.Parse(this.txtNumber.Text); //可用属性
不知道那里错了。。。。初学求救

[解决办法]
用TryParse来做