Re:索引和长度必须引用string.Parameter中的位置:length [英] Re: Index and length must refer to a location within the string.Parameter name: length
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问题描述
代码:
code:
protected void Page_Load(object sender, EventArgs e)
{
string markers = GetMarkers();
Literal1.Text = @"
<script type='text/javascript'>
function initialize() {
var mapOptions = {
center: new google.maps.LatLng(28.3213, 77.5435),
zoom: 2,
mapTypeId: google.maps.MapTypeId.ROADMAP
};
var myMap = new google.maps.Map(document.getElementById('mapArea'),
mapOptions);"
+ markers +
@"}
</script>";
}
public double ConvertDegree(string input)
{
double sd = 0.0;
double min = 0.0;
double sec = 0.0;
double deg = 0.0;
string direction = input.Substring(0, 1); // Error: Index and length must refer to a location within the string.Parameter name: length
string sign = "";
if ((direction.ToUpper() == "S") || (direction.ToUpper() == "W"))
{
sign = "-";
}
string[] arr = input.Split(new char[] { ' ' });
min = Convert.ToDouble(arr[2]);
string[] arr1 = arr[3].Split(new char[] { '.' });
sec = Convert.ToDouble(arr1[0]);
deg = Convert.ToDouble(arr[1]);
min = min / ((double)60);
sec = sec / ((double)3600);
sd = deg + min + sec;
if (!(string.IsNullOrEmpty(sign)))
{
sd = sd * (-1);
}
sd = Math.Round(sd, 6);
string sdnew = Convert.ToString(sd);
string sdnew1 = "";
sdnew1 = string.Format("{0:0.000000}", sd);
double manu = Convert.ToDouble(sdnew1.ToString());
return manu;
}
protected string GetMarkers()
{
string markers = "";
using (SqlConnection con = new
SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["HostelConnectionString"].ConnectionString))
{
SqlCommand cmd = new SqlCommand("select hi.Hostelcd, hi.Lattitude,hi.Longitude,h.HostelName from HostelDetails h left outer join Hostelinformation hi on h.Hostelcd = hi.Hostelcd order by hi.Hostelcd desc", con);
con.Open();
SqlDataReader reader = cmd.ExecuteReader();
int i = 0;
while (reader.Read())
{
i++;
markers +=
@"var marker" + i.ToString() + @" = new google.maps.Marker({
position: new google.maps.LatLng(" + ConvertDegree(reader["Lattitude"].ToString()) + ", " +
ConvertDegree(reader["Longitude"].ToString()) + ")," +
@"map: myMap,
title:'" + reader["HostelName"].ToString() + "'});";
}
}
return markers;
}
在我的数据库中,纬度和经度存储为例如:N 16 53 55 E 77 14 27
请为此运行时错误提供解决方案。
In my database lattitude and longitude are stored as Eg: N 16 53 55 E 77 14 27
Pls give the solution for this runtime error.
推荐答案
使用..
i认为输入的参数值为空或空字符串..
试试这个..
Use..
i think your parameter value for input gets null or empty string..
try this..
if(String.IsNullOrEmpty(input))
{
input="hello";
}
string direction = input.Substring(0, 1);
检查您的数据。
由于错误发生在尝试从字符串开头提取单个字符的substring命令,似乎至少有一个从数据库返回的值是空字符串:或数据库列中的NULL,在经度中或纬度 - 我们无法分辨哪一个。
但是你为什么要将它存储为字符串数据呢?要做任何有用的事情你需要它作为一个双 - 所以为什么不在你进行数据输入时将其转换为,然后只是读出来?在您真正需要时节省大量时间和精力......
Check your data.
Since the error is occurring on a substring command which tried to extract a single character starting at the beginning of the string, it would appear that at least one of the values returned from your DB is an empty string: "" or a NULL in your DB column, either in the Longitude or Latitude - we can't tell which.
But why are you storing this as string data anyway? To do anything useful with it you need it as a double - so why not convert it to that when you do the data entry, and then just read it out? Saves a lot of time and effort when you actually need it...
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