关于索引和长度必须引用该字符串内的位置。

Question

 

关于索引和长度必须引用该字符串内的位置。参数名: length  问题

string stuStr = "select Course as '课程名',(select CourseMark  from ScoreInfo where stuno='{0}' and ";
                stuStr += "ScoreInfo.CourseID=CourseInfo.CourseID ) as '成绩'  from CourseInfo where ClassID='{1}' and semester='{2}'";
                stuno = cbxstudent.Text.Substring(cbxstudent.Text.IndexOf("(", 0) + 1, 8);
                string strsql = string.Format(stuStr, stuno, gainclassID(cbxStuCls.Text, txtStuYear.Text), cbxStuSemestre.Text);
                DataSet dataset3 = new DataSet();
                dataset3 = showStuScore(strsql);
                dataGridView1.DataSource = dataset3.Tables["show"];

Answer 1

 

关于索引和长度必须引用该字符串内的位置。参数名: length  问题
                stuno = cbxstudent.Text.Substring(cbxstudent.Text.IndexOf("(", 0) + 1, 8);

这条代码报的那个错，初学者，不知道怎么改。。

Answer 2

 stuno = cbxstudent.Text.Substring(cbxstudent.Text.IndexOf("(", 0) + 1, 8);

这条报错的。

Answer 3

你出现的异常应该是ArgumentOutOfRangeException异常，你指示的SubString的length长度过大了，已经超过了cbxstudent.Text的长度了， 你应该试试改成下面：

stuno = cbxstudent.Text.Substring(cbxstudent.Text.IndexOf("(", 0) + 1, cbxstudent.Text.Length-1);

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Answer 4

换成你说的这，还是报一样的错误。

Answer 5

你能截图看看嘛？看到具体什么错误的了

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Answer 6

尝试这样的看看：

string s = "asasa(asasasa";
s.Substring(s.IndexOf("(", 0) + 1);

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Answer 7

可能先檢查 cbxstudent.Text 內容會比較好，

如果內容值是 string.Empty 這段程式就會有問題，

另外需要保證 "(" 是存在的，

不然會從字串開頭開始取值，

除非這是你的本意，否則將會是錯誤的結果，

最後建議 sql 不要這樣串字串，

會有 SQL Injection 問題。

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Frank