index超出了数组的范围意味着WPF C＃[重复]

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What is an IndexOutOfRangeException / ArgumentOutOfRangeException and how do I fix it? 3 answers

什么是IndexOutOfRangeException / ArgumentOutOfRangeException以及如何解决它? 3个答案

I try this code to display names from database in loop but this shows an error index was outside the bounds of the array meaning on this line name[j++] = Convert.ToString(reader["CategoryName"]);

我尝试使用此代码在循环中显示数据库中的名称,但这显示错误索引超出了此行名称的数组边界[j ++] = Convert.ToString(reader [“CategoryName”]);

code

 con.Open();
        int count =0;
        int j =0;
        //cmd = new SqlCommand("select * from Category");
        string[] name = new string[count];
        cmd = new SqlCommand("select CategoryName from Category",con);
        reader = cmd.ExecuteReader();
        while (reader.Read())
        {
            name[j++] = Convert.ToString(reader["CategoryName"]);
        }
        int loc = 37;
        CheckBox[] obj = new CheckBox[count];
        for (int i = 0; i < count; i++)
        {
            obj[i] = new CheckBox();
            obj[i].Location = new System.Drawing.Point(loc, 50);
            obj[i].Size = new System.Drawing.Size(80, 17);
            obj[i].Text = name[i];
            this.Controls.Add(obj[i]);
            loc += 80;

        }
        con.Close();

any help?

2 个解决方案

#1

Well you set count = 0 then you create an array with that

那么你设置count = 0然后你用它创建一个数组

string[] name = new string[count];

Which means your array will be of 0 lenght and you won't be able too assign anything to it. I suggest you change it to a List which will be much easier

这意味着你的数组将是0长度,你将无法分配任何东西。我建议你把它改成一个更容易的List

List<string> name = new List<string>();

while (reader.Read())
{
    name.Add(Convert.ToString(reader["CategoryName"]));
}

#2

At the beggining you set

在开始你的设定

int count =0;

and then you initialize the array like this:

然后你像这样初始化数组:

new string[count];

you are effectively creating an array with zero places in it. and then you loop with:

你正在有效地创建一个零位置的数组。然后你循环:

name[j++]

you access an index in the array that isn't there

您访问不存在的数组中的索引

#1