Develop Reference

Check the difference

Hi I'm building a program that will look at files at have been placed into SVN and show what files have been changed in each commit.
As i'm only wanting to show the file path. if the path is that same I only want to show the difference.
example:
First file path is:
/GEM4/trunk/src/Tools/TaxMarkerUpdateTool/Tax Marker Ripper v1/DataModifier.cs
Second file path is:
/GEM4/trunk/src/Tools/TaxMarkerUpdateTool/Tax Marker Ripper v1/Tax Marker Ripper v1.csproj
What I'd like to do is substring at the point of difference.
So in this case:
/GEM4/trunk/src/Tools/TaxMarkerUpdateTool/Tax Marker Ripper v1/
would be substringed

I hope this helps:
public string GetString(string Path1, string Path2)
{
//Split and Put everything between / in the arrays
string[] Arr_String1 = Path1.Split('/');
string[] Arr_String2 = Path2.Split('/');
string Result = "";
for (int i = 0; i <= Arr_String1.Length; i++)
{
if (Arr_String1[i] == Arr_String2[i])
{
//Puts the Content that is the same in an Result string with /
Result += Arr_String1[i] + '/';
}
else
break;
}
// If Path is identical he would add a / which we dont want
if (Result.Contains('.'))
{
Result = Result.TrimEnd('/');
}
return Result;
}

You can do this pretty easily with a loop. Basically:
public String FindCommonStart(string a, string b)
{
int length = Math.Min(a.Length, b.Length);
var common = String.Empty;
for (int i = 0; i < length; i++)
{
if (a[i] == b[i])
{
common += a[i];
}
else
{
break;
}
}
return common;
}

Something like this:
public string GetCommonStart(string a, string b)
{
if ((a == null) || (b == null))
throw new ArgumentNullException();
int Delim = 0;
int I = 0;
while ((I < a.Length) && (I < b.Length) && (a[I] == b[I]))
{
if (a[I++] == Path.AltDirectorySeparatorChar) // or Path.DirectorySeparatorChar
Delim = I;
}
return a.Substring(0, Delim);
}
Keep in mind, that this code is case-sensitive (and paths in windows in general are not).

Convert ISpreadsheetName to CellRange

I am using Telerik controls to manipulate Excel workbook. Here I am accessing Workbook Named Ranges the following way:
ISpreadsheetName Name_Level2;
workbook.Names.TryGetSpreadsheetName("IP_Stredisko_Level2_End", out Name_Level2);
Afterwards the result I get from Name_Level2.RefersTo is a plain string such as following:"=Sheet1!$A$5"
I am trying to convert this reference to a proper CellRange object, which can be used when manipulating specific cell values.
Is there any built-in method how to do the conversion, or I have to write the method myself?

In the end, as I did not manage to find anything in the documentation, I have created my own converter. Hope it helps someone.
private static CellRange GetCellRange(string sReference, string sWorkbookName)
{
if (string.IsNullOrWhiteSpace(sReference))
return null;
sReference = sReference.Replace("=" + sWorkbookName + "!", string.Empty);
sReference = sReference.Replace("$", string.Empty);
string sColumn = string.Empty;
string sRow = string.Empty;
for (int i = 0; i < sReference.Length; i++)
{
if (char.IsDigit(sReference[i]))
sRow += sReference[i];
else
sColumn += sReference[i];
}
int iRow = Convert.ToInt16(sRow) -1;
int iCol = GetColIndex(sColumn);
if (iRow >= 0 && iCol >= 0)
return new CellRange(iRow, iCol,iRow,iCol);
else
return null;
}
//accepting up to AZ
private static int GetColIndex(string sReference)
{
if (sReference.Length > 1)
{
int x = (int)sReference[1];
return 25 + ((int)sReference[1] - 65);//25 as 26 letters in alphabet -1 (start from 0)
}
return (int)sReference[0] - 65;
}

Mixed managed C++ method does not always return the same result to the calling C# code

A C++ method returns the correct value when I use a conditional breakpoint, but an incorrect value without a breakpoint.
C# method which calls C++:
bool SetProperty(Element element, Node referencePoint, List<Materializer> materializers, List<ulong> properties)
{
// Loop over STLs
for (int i = 0; i < materializers.Count; i++)
{
Materializer materializer = materializers[i];
if (materializer.IsPointInside(referencePoint.X, referencePoint.Y, referencePoint.Z, pentalTreeDatasets[i].top))
{
element.PropertyId = properties[i];
return true;
};
}
return false;
}
C++ methods in the header file:
int CountIntersects(double x, double y, double z, PentalTreeNode ^root)
{
Math3d::M3d rayPoints[2], intersectionPoint;
rayPoints[0].set(x,y,z);
rayPoints[1].set(x,y,1.0e6);
if(!root)
return 0;
else
{
int special = CountIntersects(x,y,z,root->special);
if (x <= root->xMax && x >= root->xMin && y <= root->yMax && y >= root->yMin)
{
if( _stlMesh->IsRayIntersectsPoly(root->index, rayPoints, intersectionPoint))
{
return (1 + special);
}
else
return special;
}
else
{
if (y>root->yMax)
{
return (CountIntersects(x,y,z,root->top)+special);
}
else if(y<root->yMin)
{
return (CountIntersects(x,y,z,root->bottom)+special);
}
else if(x<root->xMin)
{
return (CountIntersects(x,y,z,root->left)+special);
}
else if(x>root->xMax)
{
return (CountIntersects(x,y,z,root->right)+special);
}
else
return special;
}
}
}
bool IsPointInside(double x, double y, double z, PentalTreeNode ^root)
{
int intersectionCount = 0;
Math3d::M3d rayPoints[2], intersectionPoint;
rayPoints[0].set(x,y,z);
rayPoints[1].set(x,y,1.0e6);
if(_box->IsContainingPoint(x,y,z))
{
intersectionCount=CountIntersects(x,y,z,root);
return (intersectionCount%2!=0);
}
}
C++ methods in other header files:
bool IsRayIntersectsPoly(int nPolygonIndex, Math3d::M3d RayPoints[2], CVector3D& IntersectionPoint)
{
CMeshPolygonBase& Poly = m_PolygonArray[nPolygonIndex];
CArrayResultI Result;
int* pPolygonPoints = GetPolygonPoints(Poly, Result);
Math3d::MPlane TrianglePlane;
double Atmp[3], A;
CVector3D* pPoints[3];
pPoints[0] = &m_PointArray[*pPolygonPoints].m_Position;
for(int i = 1; i < Result.GetSize() - 1; i++)
{
pPoints[1] = &m_PointArray[*(pPolygonPoints+i)].m_Position;
pPoints[2] = &m_PointArray[*(pPolygonPoints+i+1)].m_Position;
TrianglePlane.Init(*pPoints[0], *pPoints[1], *pPoints[2]);
TrianglePlane.IntersectLine(RayPoints[0], RayPoints[1], IntersectionPoint);
A = GetTriangleArea(*pPoints[0], *pPoints[1], *pPoints[2]);
for(int j = 0; j < 3; j++)
{
Atmp[j] = GetTriangleArea(*pPoints[j], *pPoints[(j+1)%3], IntersectionPoint);
}
if( fabs(A - Atmp[0] - Atmp[1] - Atmp[2]) < 1.0e-5 ) return true;
}
return false;
};
double GetTriangleArea(CVector3D& T1, CVector3D& T2, CVector3D& T3)
{
double a, b, c, s;
a = (T1 - T2).length();
b = (T2 - T3).length();
c = (T3 - T1).length();
s = 0.5 * (a + b + c);
return( sqrt(s * (s - a)* (s - b)* (s - c)) );
}
When I start the program which calls SetProperty() within the for-loop, the results for some iterator values are wrong. When I set conditional breakpoints for critical iterator values in the for-loop and step over it, then the result is OK for that item. What may be the problem?
This is method in which I post breakpoint. For example, for critical element.Id==2393.
private void StartButton_Click(object sender, EventArgs e)
{
DateTime startTime = DateTime.Now;
List<Materializer> materializers = new List<Materializer>();
List<ulong> properties = new List<ulong>();
// Load STLs
for (int i = 0; (int)i < (this.dataGridView.RowCount - 1); i++)
{
if (dataGridView.Rows[i].Cells[1].Value != null && (string)dataGridView.Rows[i].Cells[1].Value != "")
{
Materializer materializer = new Materializer();
materializer.LoadSTLMesh(dataGridView.Rows[i].Cells[0].Value.ToString());
materializers.Add(materializer);
properties.Add((ulong)dataGridView.Rows[i].Cells[1].Tag);
}
}
CreatePentalTrees(materializers);
int processedElementCount = 0;
int changedElementCount = 0;
// Loop over elements
foreach (Element element in model.ElementsList.Values)
if ((element.Topology == 7 || element.Topology == 8) && !lockedProperties.ContainsKey(element.PropertyId)) // 3D elements only
{
Node center = this.CenterPoint(element, model.NodesList);
if (element.Id == 2393)
{
//if breakpoints thats ok, else not ok
Console.WriteLine(element.Id);
Console.WriteLine(element.PropertyId);
}
if (SetProperty(element, center, materializers, properties)) // Check for center point
{
//changedElements.Add(element.Id, true);
changedElementCount++;
}
else
{
// Check for all nodes if center point does not belong to any STL
int[] nodeOrder;
switch (element.Topology)
{
case 7:
nodeOrder = wedgeNodeOrder;
break;
case 8:
nodeOrder = brickNodeOrder;
break;
default:
throw new Exception("Unknown topology " + element.Topology.ToString());
}
for (int i = 0; i < nodeOrder.Length; i++)
{
Node node = model.NodesList[element.NodeIds[nodeOrder[i]]];
if (SetProperty(element, node, materializers, properties))
{
//changedElements.Add(element.Id, true);
changedElementCount++;
break;
}
}
}
if (++processedElementCount % 100 == 0)
{
labelTime.Text = "Changed/processed elements: " + changedElementCount.ToString() + "/" + processedElementCount.ToString();
labelTime.Refresh();
Application.DoEvents();
}
}
DateTime endTime = DateTime.Now;
labelTime.Text = "Total time: " + (endTime - startTime).TotalSeconds.ToString() + " s";
MessageBox.Show("Completed.");
SaveFileDialog saveFileDlg = new SaveFileDialog();
saveFileDlg.Title = "Save FEMAP neutral file";
saveFileDlg.Filter = "(*.neu)|*.neu";
if (saveFileDlg.ShowDialog() == System.Windows.Forms.DialogResult.OK)
{
FemapNeutral.ExportNeu(saveFileDlg.FileName, model);
}
}

You seem to be calling a lot of methods you haven't listed, and/or the wall of code made me get lost. Adding that code won't help: reducing your problem to a simpler one that demonstrates the problem might.
However, the most likely cause of your problem, if you have unmanaged code reading managed data, is that you failed to marshal or pin the data prior to using the managed code.
Unpinned data can be moved around by the garbage collector in unexpected ways.

For Loop in C# not looping

I have an issue with a Loop that doesn't actually loop. I've posted a simplified version of my code below. Basically, using the NPOI excel library, I have an excel file with data on the first and second sheet, so I need to do a loop to get through both sheets.
Below is what I have done so far, however this only works through the first sheet and then exits. It fails to increment the variable w. As you can see, there are other loops implemented in this code which function fine so I don't get it.
It's been a very long day and perhaps I'm missing something very simple. I could have it placed wrong or something. If anyone else can spot what I might be doing wrong I'd be very grateful :)
public class SalesFileProcessor : ISalesProcessor
{
public List<FTPSalesRow> ProcessSalesFile(string filename)
{
try
{
using (FileStream fs = File.Open(filename, FileMode.Open, FileAccess.Read))
{
int numberOfSheets = 2;
//Loop through sheets - does not work
for (int w = 0; w <= numberOfSheets; w++)
{
HSSFWorkbook templateWorkbook = new HSSFWorkbook(fs);
HSSFSheet sheet = templateWorkbook.GetSheetAt(w);
HSSFRow row = null;
for (int i = 1; i <= sheet.LastRowNum; i++)
{
FTPSalesDetails t = null;
int currentColumn = 0;
try
{
ModelContainer ctn = new ModelContainer();
row = sheet.GetRow(i);
if (row == null)
{
continue;
}
t = new FTPSalesDetails
{
RowNumber = i,
InvoiceDate = GetCellValue(row.GetCell(0)),
CountrySoldIn = GetCellValue(row.GetCell(1)),
NetUnitsSold = GetCellValue(row.GetCell(2)),
Item = GetCellValue(row.GetCell(3)),
ProductCode = GetCellValue(row.GetCell(5)),
};
if (t.ProductCode == null && t.NetUnitsSold == null)
{
return null;
}
int Qty = int.Parse(t.NetUnitsSold);
for (int x = 0; x < Qty; x++)
{
ItemSale ts = new ItemSale
{
ItemID = GetItemID(t.ProductCode),
ManufacturerID = GetManufacturerID("Samsung"),
DateSold = DateTime.Now,
};
ctn.AddToItemSales(ts);
ctn.SaveChanges();
}
}
catch (IndexOutOfRangeException) { }
}
} //End Loop - the one that doesn't work
}
}
catch (IOException exp)
{
throw new FTPSalesFileProcessingException("Could not open the Sales data file", exp);
}
catch (Exception exp)
{
throw new FTPSalesFileProcessingException("An unknown eror occured during processing the file", exp);
}
return null;
}

if (t.ProductCode == null && t.NetUnitsSold == null)
{
return null;
}
I'm going to guess that this is being hit, causing your entire function to exit. If you are trying to exit out of that iteration of the for loop try a break; instead, or a continue as Mike M pointed out in the comments.

For what you say, assuming your variables are all ok that is the loop is not empty... have you checked you're not hiting this line in the first iteration?
if (t.ProductCode == null && t.NetUnitsSold == null)
{
return null;
}

Looking at the code, the only obvious thing sticking out to me is:
HSSFSheet sheet = templateWorkbook.GetSheetAt(w);
HSSFRow row = null;
for (int i = 1; i <= sheet.LastRowNum; i++)
I would guess that sheet.LastRowNum either equals 0 or 1.

Maybe the indexOutOfRangeException is thrown and thats beacuse you have only one iteration, or instead of <= you sholud use <. Does the sheet numbers start with zero ?

Evaluating string "3*(4+2)" yield int 18 [duplicate]

This question already has answers here:
Is it possible to compile and execute new code at runtime in .NET?
(15 answers)
Closed 9 years ago.
Is there a function the .NET framework that can evaluate a numeric expression contained in a string and return the result? F.e.:
string mystring = "3*(2+4)";
int result = EvaluateExpression(mystring);
Console.Writeln(result); // Outputs 18
Is there a standard framework function that you can replace my EvaluateExpression method with?

If you want to evaluate a string expression use the below code snippet.
using System.Data;
DataTable dt = new DataTable();
var v = dt.Compute("3 * (2+4)","");

Using the compiler to do implies memory leaks as the generated assemblies are loaded and never released. It's also less performant than using a real expression interpreter. For this purpose you can use Ncalc which is an open-source framework with this solely intent. You can also define your own variables and custom functions if the ones already included aren't enough.
Example:
Expression e = new Expression("2 + 3 * 5");
Debug.Assert(17 == e.Evaluate());

Try this:
static double Evaluate(string expression) {
var loDataTable = new DataTable();
var loDataColumn = new DataColumn("Eval", typeof (double), expression);
loDataTable.Columns.Add(loDataColumn);
loDataTable.Rows.Add(0);
return (double) (loDataTable.Rows[0]["Eval"]);
}

You could look at "XpathNavigator.Evaluate" I have used this to process mathematical expressions for my GridView and it works fine for me.
Here is the code I used for my program:
public static double Evaluate(string expression)
{
return (double)new System.Xml.XPath.XPathDocument
(new StringReader("<r/>")).CreateNavigator().Evaluate
(string.Format("number({0})", new
System.Text.RegularExpressions.Regex(#"([\+\-\*])")
.Replace(expression, " ${1} ")
.Replace("/", " div ")
.Replace("%", " mod ")));
}

This is a simple Expression Evaluator using Stacks
public class MathEvaluator
{
public static void Run()
{
Eval("(1+2)");
Eval("5*4/2");
Eval("((3+5)-6)");
}
public static void Eval(string input)
{
var ans = Evaluate(input);
Console.WriteLine(input + " = " + ans);
}
public static double Evaluate(String input)
{
String expr = "(" + input + ")";
Stack<String> ops = new Stack<String>();
Stack<Double> vals = new Stack<Double>();
for (int i = 0; i < expr.Length; i++)
{
String s = expr.Substring(i, 1);
if (s.Equals("(")){}
else if (s.Equals("+")) ops.Push(s);
else if (s.Equals("-")) ops.Push(s);
else if (s.Equals("*")) ops.Push(s);
else if (s.Equals("/")) ops.Push(s);
else if (s.Equals("sqrt")) ops.Push(s);
else if (s.Equals(")"))
{
int count = ops.Count;
while (count > 0)
{
String op = ops.Pop();
double v = vals.Pop();
if (op.Equals("+")) v = vals.Pop() + v;
else if (op.Equals("-")) v = vals.Pop() - v;
else if (op.Equals("*")) v = vals.Pop()*v;
else if (op.Equals("/")) v = vals.Pop()/v;
else if (op.Equals("sqrt")) v = Math.Sqrt(v);
vals.Push(v);
count--;
}
}
else vals.Push(Double.Parse(s));
}
return vals.Pop();
}
}

static double Evaluate(string expression) {
var loDataTable = new DataTable();
var loDataColumn = new DataColumn("Eval", typeof (double), expression);
loDataTable.Columns.Add(loDataColumn);
loDataTable.Rows.Add(0);
return (double) (loDataTable.Rows[0]["Eval"]);
}
Explanation of how it works:
First, we make a table in the part var loDataTable = new DataTable();, just like in a Data Base Engine (MS SQL for example).
Then, a column, with some specific parameters (var loDataColumn = new DataColumn("Eval", typeof (double), expression);).
The "Eval" parameter is the name of the column (ColumnName attribute).
typeof (double) is the type of data to be stored in the column, which is equal to put System.Type.GetType("System.Double"); instead.
expression is the string that the Evaluate method receives, and is stored in the attribute Expression of the column. This attribute is for a really specific purpose (obvious), which is that every row that's put on the column will be fullfilled with the "Expression", and it accepts practically wathever can be put in a SQL Query. Refer to http://msdn.microsoft.com/en-us/library/system.data.datacolumn.expression(v=vs.100).aspx to know what can be put in the Expression attribute, and how it's evaluated.
Then, loDataTable.Columns.Add(loDataColumn); adds the column loDataColumn to the loDataTable table.
Then, a row is added to the table with a personalized column with a Expression attribute, done via loDataTable.Rows.Add(0);. When we add this row, the cell of the column "Eval" of the table loDataTable is fullfilled automatically with its "Expression" attribute, and, if it has operators and SQL Queries, etc, it's evaluated and then stored to the cell, so, here happens the "magic", the string with operators is evaluated and stored to a cell...
Finally, just return the value stored to the cell of the column "Eval" in row 0 (it's an index, starts counting from zero), and making a conversion to a double with return (double) (loDataTable.Rows[0]["Eval"]);.
And that's all... job done!
And here a code eaiser to understand, which does the same... It's not inside a method, and it's explained too.
DataTable MyTable = new DataTable();
DataColumn MyColumn = new DataColumn();
MyColumn.ColumnName = "MyColumn";
MyColumn.Expression = "5+5/5"
MyColumn.DataType = typeof(double);
MyTable.Columns.Add(MyColumn);
DataRow MyRow = MyTable.NewRow();
MyTable.Rows.Add(MyRow);
return (double)(MyTable.Rows[0]["MyColumn"]);
First, create the table with DataTable MyTable = new DataTable();
Then, a column with DataColumn MyColumn = new DataColumn();
Next, we put a name to the column. This so we can search into it's contents when it's stored to the table. Done via MyColumn.ColumnName = "MyColumn";
Then, the Expression, here we can put a variable of type string, in this case there's a predefined string "5+5/5", which result is 6.
The type of data to be stored to the column MyColumn.DataType = typeof(double);
Add the column to the table... MyTable.Columns.Add(MyColumn);
Make a row to be inserted to the table, which copies the table structure DataRow MyRow = MyTable.NewRow();
Add the row to the table with MyTable.Rows.Add(MyRow);
And return the value of the cell in row 0 of the column MyColumn of the table MyTable with return (double)(MyTable.Rows[0]["MyColumn"]);
Lesson done!!!

This is right to left execution, so need to use proper parathesis to execute expression
// 2+(100/5)+10 = 32
//((2.5+10)/5)+2.5 = 5
// (2.5+10)/5+2.5 = 1.6666
public static double Evaluate(String expr)
{
Stack<String> stack = new Stack<String>();
string value = "";
for (int i = 0; i < expr.Length; i++)
{
String s = expr.Substring(i, 1);
char chr = s.ToCharArray()[0];
if (!char.IsDigit(chr) && chr != '.' && value != "")
{
stack.Push(value);
value = "";
}
if (s.Equals("(")) {
string innerExp = "";
i++; //Fetch Next Character
int bracketCount=0;
for (; i < expr.Length; i++)
{
s = expr.Substring(i, 1);
if (s.Equals("("))
bracketCount++;
if (s.Equals(")"))
if (bracketCount == 0)
break;
else
bracketCount--;
innerExp += s;
}
stack.Push(Evaluate(innerExp).ToString());
}
else if (s.Equals("+")) stack.Push(s);
else if (s.Equals("-")) stack.Push(s);
else if (s.Equals("*")) stack.Push(s);
else if (s.Equals("/")) stack.Push(s);
else if (s.Equals("sqrt")) stack.Push(s);
else if (s.Equals(")"))
{
}
else if (char.IsDigit(chr) || chr == '.')
{
value += s;
if (value.Split('.').Length > 2)
throw new Exception("Invalid decimal.");
if (i == (expr.Length - 1))
stack.Push(value);
}
else
throw new Exception("Invalid character.");
}
double result = 0;
while (stack.Count >= 3)
{
double right = Convert.ToDouble(stack.Pop());
string op = stack.Pop();
double left = Convert.ToDouble(stack.Pop());
if (op == "+") result = left + right;
else if (op == "+") result = left + right;
else if (op == "-") result = left - right;
else if (op == "*") result = left * right;
else if (op == "/") result = left / right;
stack.Push(result.ToString());
}
return Convert.ToDouble(stack.Pop());
}

You could fairly easily run this through the CSharpCodeProvider with suitable fluff wrapping it (a type and a method, basically). Likewise you could go through VB etc - or JavaScript, as another answer has suggested. I don't know of anything else built into the framework at this point.
I'd expect that .NET 4.0 with its support for dynamic languages may well have better capabilities on this front.

I recently needed to do this for a project and I ended up using IronPython to do it. You can declare an instance of the engine, and then pass any valid python expression and get the result. If you're just doing simple math expressions, then it would suffice. My code ended up looking similar to:
IronPython.Hosting.PythonEngine pythonEngine = new IronPython.Hosting.PythonEngine();
string expression = "3*(2+4)";
double result = pythonEngine.EvaluateAs<double>(expression);
You'd probably not want to create the engine for each expression. You also need a reference to IronPython.dll

EDIT: Realised i should really bring the addition and subtraction out seperately aswell to make it a little bit more BODMAS compliant.
Big thanks to Rajesh Jinaga for his Stack based approach. I found it really useful for my needs. The following code is a slight modification of Rajesh's method, which processes divisions first, then multiplications, then finishes up with addition and subtraction. It will also allow the use of booleans in the expressions, where true is treated as 1 and false 0. allowing the use of boolean logic in expressions.
public static double Evaluate(string expr)
{
expr = expr.ToLower();
expr = expr.Replace(" ", "");
expr = expr.Replace("true", "1");
expr = expr.Replace("false", "0");
Stack<String> stack = new Stack<String>();
string value = "";
for (int i = 0; i < expr.Length; i++)
{
String s = expr.Substring(i, 1);
// pick up any doublelogical operators first.
if (i < expr.Length - 1)
{
String op = expr.Substring(i, 2);
if (op == "<=" || op == ">=" || op == "==")
{
stack.Push(value);
value = "";
stack.Push(op);
i++;
continue;
}
}
char chr = s.ToCharArray()[0];
if (!char.IsDigit(chr) && chr != '.' && value != "")
{
stack.Push(value);
value = "";
}
if (s.Equals("("))
{
string innerExp = "";
i++; //Fetch Next Character
int bracketCount = 0;
for (; i < expr.Length; i++)
{
s = expr.Substring(i, 1);
if (s.Equals("(")) bracketCount++;
if (s.Equals(")"))
{
if (bracketCount == 0) break;
bracketCount--;
}
innerExp += s;
}
stack.Push(Evaluate(innerExp).ToString());
}
else if (s.Equals("+") ||
s.Equals("-") ||
s.Equals("*") ||
s.Equals("/") ||
s.Equals("<") ||
s.Equals(">"))
{
stack.Push(s);
}
else if (char.IsDigit(chr) || chr == '.')
{
value += s;
if (value.Split('.').Length > 2)
throw new Exception("Invalid decimal.");
if (i == (expr.Length - 1))
stack.Push(value);
}
else
{
throw new Exception("Invalid character.");
}
}
double result = 0;
List<String> list = stack.ToList<String>();
for (int i = list.Count - 2; i >= 0; i--)
{
if (list[i] == "/")
{
list[i] = (Convert.ToDouble(list[i - 1]) / Convert.ToDouble(list[i + 1])).ToString();
list.RemoveAt(i + 1);
list.RemoveAt(i - 1);
i -= 2;
}
}
for (int i = list.Count - 2; i >= 0; i--)
{
if (list[i] == "*")
{
list[i] = (Convert.ToDouble(list[i - 1]) * Convert.ToDouble(list[i + 1])).ToString();
list.RemoveAt(i + 1);
list.RemoveAt(i - 1);
i -= 2;
}
}
for (int i = list.Count - 2; i >= 0; i--)
{
if (list[i] == "+")
{
list[i] = (Convert.ToDouble(list[i - 1]) + Convert.ToDouble(list[i + 1])).ToString();
list.RemoveAt(i + 1);
list.RemoveAt(i - 1);
i -= 2;
}
}
for (int i = list.Count - 2; i >= 0; i--)
{
if (list[i] == "-")
{
list[i] = (Convert.ToDouble(list[i - 1]) - Convert.ToDouble(list[i + 1])).ToString();
list.RemoveAt(i + 1);
list.RemoveAt(i - 1);
i -= 2;
}
}
stack.Clear();
for (int i = 0; i < list.Count; i++)
{
stack.Push(list[i]);
}
while (stack.Count >= 3)
{
double right = Convert.ToDouble(stack.Pop());
string op = stack.Pop();
double left = Convert.ToDouble(stack.Pop());
if (op == "<") result = (left < right) ? 1 : 0;
else if (op == ">") result = (left > right) ? 1 : 0;
else if (op == "<=") result = (left <= right) ? 1 : 0;
else if (op == ">=") result = (left >= right) ? 1 : 0;
else if (op == "==") result = (left == right) ? 1 : 0;
stack.Push(result.ToString());
}
return Convert.ToDouble(stack.Pop());
}
I know there is likely to be a cleaner way of doing it, thought id just share the first look at it in case anyone finds it usefull.

Many thanks to Ramesh. I used a version of his simple code to pull a string out a database and use it to do boolean operations in my code.
x is a number like 1500 or 2100 or whatever.
function would be a stored evaluation like x > 1400 and x < 1600
function = relation[0].Replace("and","&&").Replace("x",x);
DataTable f_dt = new DataTable();
var f_var = f_dt.Compute(function,"");
if (bool.Parse(f_var.ToString()) { do stuff }

There is not. You will need to use some external library, or write your own parser. If you have the time to do so, I suggest to write your own parser as it is a quite interesting project. Otherwise you will need to use something like bcParser.

Short answer: I don't think so. C# .Net is compiled (to bytecode) and can't evaluate strings at runtime, as far as I know. JScript .Net can, however; but I would still advise you to code a parser and stack-based evaluator yourself.