Re: Read width & Height of jpeg file - C# Discussion Boards

Bojja Lakshmi30-Jun-07 21:40

30-Jun-07 21:40

Hi,

how i can validate a formula.

Formula contains columns of table and operators.

if suppose c1,c2,c3 are columns of table, c1 is of type string, cs is decimal and c3 is int.

formula may be a+(b*c),or a*(b/c)

lakshmi

Re: Formula validation

Christian Graus30-Jun-07 22:10

Christian Graus

30-Jun-07 22:10

c1 needs to be turned into a number, with int.TryParse or double.TryParse. Then it will just work. Otherwise, it's not possible.

Christian Graus - Microsoft MVP - C++

"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )

why DataView.RowFilter run more solwer then DataTable.Select

alonesword30-Jun-07 21:02

alonesword

30-Jun-07 21:02

why DataView.RowFilter is more solwer than DataTable.Select function?

using the following code to test.

class Program
{
const int ROWS_COUNT = 50; // 设置处理数据大小。单位：w 万
const int ROWS_COUNT_UNIT = 10000; // 数据行单位：万
const double ROWS_TOTAL_COUNT = ROWS_COUNT * ROWS_COUNT_UNIT; // 总循环次数
const double ROWS_SHOW_INFO_LINE = ROWS_TOTAL_COUNT / 10; // 显示进度
private static string SAVE_FILE_NAME = string.Format("{0}w_{1}", ROWS_COUNT.ToString(), DateTime.Now.ToString("yyyyMMddhhmmss"));
private static StringBuilder builder = new StringBuilder(string.Format("ROWS COUNT :{0}w\n", ROWS_COUNT));
private static DataTable mDataTable = null;
private static DataView dv = null;
private static string str = string.Empty;

static void Main(string[] args)
{
// 添加数据行
DateTime start = DateTime.Now;
AddData();
str = string.Format("cost [ {0} ms ] to add [ {1}w ] rows.\n{2}\n",
(DateTime.Now.Subtract(start).TotalMilliseconds.ToString()),
ROWS_COUNT.ToString(),
"----- AddData() END -----\n");
Console.WriteLine(str);
builder.AppendFormat(str);

// 添加 DataTable 的主键
start = DateTime.Now;
AddPrimaryKey(true);
str = string.Format("cost [ {0} ms ] to AddPrimaryKey().\n{1}\n",
(DateTime.Now.Subtract(start).TotalMilliseconds.ToString()),
"----- AddPrimaryKey() END -----\n");
Console.WriteLine(str);
builder.AppendFormat(str);

// 循环进行 10 次数据过滤测试
start = DateTime.Now;
int times = 0;
string enter = string.Empty;
while ((++times) < 11)
{
str = string.Format("running {0} times ...\n", times.ToString());
Console.BackgroundColor = ConsoleColor.Red;
Console.WriteLine(str);
Console.ResetColor();
builder.AppendFormat(str);
Test();
builder.Append("\n\n");
}
str = string.Format("\ncost [ {0} ms ] to WHILE loop.\n",
(DateTime.Now.Subtract(start).TotalMilliseconds.ToString()));
Console.WriteLine(str);
builder.AppendFormat(str);

// 测试结果输入到文件中
WriteToFile(builder.ToString());

// 提示用户操作
Console.WriteLine("Press any key to continue ...");
Console.ReadLine();
}

///

/// 创建dataTable
///

private static void AddData()
{
Console.WriteLine("Adding data ... ");

mDataTable = null;
mDataTable = new DataTable("test");

DataColumn dc = new DataColumn("index", typeof(double));
dc.DefaultValue = 3000;
mDataTable.Columns.Add(dc);
mDataTable.Columns.Add(new DataColumn("content", typeof(string)));

DateTime start = DateTime.Now;
TimeSpan end;

double rowsCount = ROWS_TOTAL_COUNT + 1;
DataRow row = null;
for (int i = 1; i < rowsCount; i++)
{
if (0 == (i % ROWS_SHOW_INFO_LINE))
{
end = DateTime.Now.Subtract(start);
str = string.Format("Readed {0} rows [ {1} ms]...\n\n", i.ToString(), end.TotalMilliseconds.ToString());
Console.WriteLine(str);
builder.AppendFormat(str);
start = DateTime.Now;
}
// 1000w 数据时，出现了 SystemOutOfMemory 的异常
row = mDataTable.NewRow();

//row["index"] = i;
row["content"] = i.ToString();

mDataTable.Rows.Add(row);
}

mDataTable.AcceptChanges();

Console.Clear();
}

///

/// 添加主键值
///

/// <param name="add" />
private static void AddPrimaryKey(bool add)
{
Console.WriteLine("Adding Primarykey ...");
DateTime start;

if (add)
{
// add PrimaryKey columns
int key = mDataTable.PrimaryKey.Length;
DataColumn[] dcs = new DataColumn[key + 2];
dcs[key + 0] = mDataTable.Columns["index"];
dcs[key + 1] = mDataTable.Columns["content"];

start = DateTime.Now;
mDataTable.PrimaryKey = dcs;
str = string.Format("cost [ {0} ms ] mDataTable.PrimaryKey...\n", (DateTime.Now.Subtract(start).TotalMilliseconds.ToString()));
Console.WriteLine(str);
builder.AppendFormat(str);
}

start = DateTime.Now;
dv = null;
dv = mDataTable.DefaultView;
str = string.Format("cost [ {0} ms ] mDataTable.DefaultView...\n", (DateTime.Now.Subtract(start).TotalMilliseconds.ToString()));
Console.WriteLine(str);
builder.AppendFormat(str);

builder.Append("PrimaryKey Columns Details;\n");
foreach (DataColumn dc in mDataTable.PrimaryKey)
{
builder.AppendFormat("Column Name: \t{0}\nColumn DataType: \t{1}\n", dc.ColumnName, dc.DataType.Name);
}
}

///

/// 数据筛选测试
///

private static void Test()
{
const string CONDITIONS_1 = "index < 80000";
const string CONDITIONS_2 = "index < 80000 or (content LIKE '%200%')";

SelectFromDatatable(CONDITIONS_1);
SelectFromDatatable(CONDITIONS_2);

FilterDataView(CONDITIONS_1);
FilterDataView(CONDITIONS_2);
}

///

/// 将结果记录到文件
///

/// <param name="content" /><文件内容/param>
private static void WriteToFile(string content)
{
try
{
System.IO.StreamWriter sw = new System.IO.StreamWriter(string.Format("{0}.txt", SAVE_FILE_NAME), false, Encoding.UTF8);
sw.Write(content);
sw.Close();
sw = null;
}
catch (Exception exp)
{
System.Diagnostics.Debug.WriteLine(exp.Message);
}
}

///

/// 通过DataTabl.Select 过滤数据
///

/// <param name="condtions" />
private static void SelectFromDatatable(string condtions)
{
DateTime start = DateTime.Now;
start = DateTime.Now;
mDataTable.Select(condtions);
builder.AppendFormat("mDataTable.Select(\"{0}\"):\n\t{1} ms\n", condtions, (DateTime.Now.Subtract(start).TotalMilliseconds.ToString()));
}

///

/// 通过 DataTable.DefaultView.RowFilter 过滤数据
///

/// <param name="conditions" />
private static void FilterDataView(string conditions)
{
DateTime start = DateTime.Now;
start = DateTime.Now;
dv.RowFilter = conditions;
builder.AppendFormat("dv.RowFilter = \"{0}\": \n\t{1} ms\n", conditions, (DateTime.Now.Subtract(start).TotalMilliseconds.ToString()));
}
}

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how to move in records?

s_nazari@yahoo.com30-Jun-07 20:52

s_nazari@yahoo.com

30-Jun-07 20:52

hi
i am new in c#.net.
i want to move among some records in database
for example go to the first record,last record,next record,previus record
please help me.

somi

Re: how to move in records?

Christian Graus30-Jun-07 21:22

Christian Graus

30-Jun-07 21:22

1 - don't use your email as a username, it will get you spam
2 - there are tons of articles on the web on this, you should also buy a book and work through it, if you're new to C++.

All you need to do is store a number to represent the index of the record you want to read, and use that to read a record when a button is pressed.

I answered this same question the other day, worded exactly the same. Was it you ? If so, the reason you didn't understand my answer, is that you need to learn some basics first.

Christian Graus - Microsoft MVP - C++

"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )

Re: how to move in records?

Robert Rohde1-Jul-07 2:49

Robert Rohde

1-Jul-07 2:49

Christian Graus wrote:
I answered this same question the other day, worded exactly the same.

Then its valid to just post the same response, but you should at least have replaced C++ with C# in this forum Wink | ;)

.

Robert

Read width & Height of jpeg file

Alaric_30-Jun-07 20:52

Alaric_

30-Jun-07 20:52

Hi Guys,
I'm trying to get into XNA v1.0 (..last time I touched it was Beta 1.) ...So, I'm building myself a terrain loader. Trying to get my Terrain class set up so that it can be given a heightmap file and it can initialize the size of the data array based upon the width & height of the file that is passed to it. Does anyone know of a way(preferrably a simple way) of accepting the path of a jpeg and getting the width and height out of the FileInfo?(I'm making an assumption that is where it is located, but I do not know for a fact)

Welcome my son...Welcome..to the Machine