Develop Reference

Serialize arithmetic expression-tree

I'm doing a simple task for investigation purposes. The problem is as follows:
Create an arithmetic expression with variables.
Build an AST for the expression.
Send it to the server (using Sockets)
Calculate an result of the server side and return the results.
Now I can to build a tree. This method doing it:
private readonly Stack<Expression> expressionStack = new Stack<Expression>();
private readonly Stack<Symbol> operatorStack = new Stack<Symbol>();
private readonly List<string> parameters = new List<string>();
public Expression<Func<decimal[], decimal>> Parse(string expression)
{
if (string.IsNullOrWhiteSpace(expression))
{
return s => 0;
}
var arrayParameter = Expression.Parameter(typeof(decimal[]), "args");
parameters.Clear();
operatorStack.Clear();
expressionStack.Clear();
using (var reader = new StringReader(expression))
{
int peek;
while ((peek = reader.Peek()) > -1)
{
var next = (char)peek;
if (char.IsDigit(next))
{
expressionStack.Push(ReadOperand(reader));
continue;
}
if (char.IsLetter(next))
{
expressionStack.Push(ReadParameter(reader, arrayParameter));
continue;
}
if (Operation.IsDefined(next))
{
if (next == '-' && expressionStack.Count == 0)
{
reader.Read();
operatorStack.Push(Operation.UnaryMinus);
continue;
}
var currentOperation = ReadOperation(reader);
EvaluateWhile(() => operatorStack.Count > 0 && operatorStack.Peek() != Parentheses.Left &&
currentOperation.Precedence <= ((Operation)operatorStack.Peek()).Precedence);
operatorStack.Push(currentOperation);
continue;
}
if (next == '(')
{
reader.Read();
operatorStack.Push(Parentheses.Left);
if (reader.Peek() == '-')
{
reader.Read();
operatorStack.Push(Operation.UnaryMinus);
}
continue;
}
if (next == ')')
{
reader.Read();
EvaluateWhile(() => operatorStack.Count > 0 && operatorStack.Peek() != Parentheses.Left);
operatorStack.Pop();
continue;
}
if (next == ' ')
{
reader.Read();
}
else
{
throw new ArgumentException(string.Format("Encountered invalid character {0}", next),
"expression");
}
}
}
EvaluateWhile(() => operatorStack.Count > 0);
return Expression.Lambda<Func<decimal[], decimal>>(expressionStack.Pop(), arrayParameter);
}
This method works, and returns the expected result.
Before being sent to the server I want to serialize a tree to binary type. My question is as follows. Which is the simplest way I can apply for this?
I found a lot of solutions for LINQ serialization, but they are too big. I don't need the full functionality of these solutions. In addition, usually, they provide the JSON or XML-serialization, but I need a binary serialization.
Can somebody suggest a simple and easy solution for this problem?

Multithread, Linq to Sql, ConcurrentDictonary Fails Remove

I have a ConcurrentDictionary of Attributes for products. These attributes have the product ID and values for the names of the attribute and any options the attribute has. I have this ConcurrentDictionary because I have threads that are created to handle each attribute in the dictionary by attribute name.
if (knownAttribute.AttributeType.Value.Equals("Product Specification"))
{
Console.WriteLine("Started a thread for: " + knownAttribute.AttributeTypeId + ", " + knownAttribute.Value);
while (true)
{
/* if (AS400SpecificationAttributes.IsEmpty && knownSpecificationBag.IsEmpty && gatherRowsTasks.All(x => x.IsCompleted))
break;*/
AS400SpecificationAttribute AS400SpecificationAttributeWork = null;
AS400SpecificationAttributeWork = knownSpecificationBag.Keys.FirstOrDefault(x => x.AttributeName == knownAttribute.Value);
if (AS400SpecificationAttributeWork != null)
{
var product = ctx.Products.FirstOrDefault(x => x.ProductNumber == AS400SpecificationAttributeWork.ProductNumber);
if (product == null)
continue;
var productAttribute = new ProductAttribute();
productAttribute.Attribute = knownAttribute;
if (AS400SpecificationAttributeWork.AttributeValue != null)
{
var knownAttributeOption = ctx.AttributeOptions.FirstOrDefault(x => x.Attribute.Equals(knownAttribute) && x.Value.Equals(AS400SpecificationAttributeWork.AttributeValue));
if (knownAttributeOption == null)
{
knownAttributeOption = new AttributeOption();
knownAttributeOption.Value = AS400SpecificationAttributeWork.AttributeValue;
knownAttributeOption.Attribute = knownAttribute;
ctx.AttributeOptions.InsertOnSubmit(knownAttributeOption);
ctx.SubmitChanges();
}
productAttribute.AttributeOption = knownAttributeOption;
productAttribute.AttributeOptionId = knownAttributeOption.Id;
}
product.ProductAttributes.Add(productAttribute);
ctx.SubmitChanges();
string tmpstr = null;
if (!knownSpecificationBag.TryRemove(AS400SpecificationAttributeWork, out tmpstr))
Thread.Sleep(50);
}
else
{
if (tryCounter < 5)
{
tryCounter++;
Thread.Sleep(1000);
Console.WriteLine("Thread waiting for work: Product Specification:" + knownAttribute.Value);
continue;
}
else
{
int outVal;
threadTracker.TryRemove("Product Specification:" + knownAttribute.Value, out outVal);
Console.WriteLine("Closing Thread: Product Specification:" + knownAttribute.Value);
break;
}
}
Thread.Sleep(50);
}
It seems like the following Attribute element refuses to be removed.
I don't understand why. If i put it in a while(!dic.tryRemove(ele)) it will forever be stuck and never move from there.
There may be an error somewhere within the thread but I have no idea why.

This statement
if (!knownSpecificationBag.TryRemove(AS400SpecificationAttributeWork, out tmpstr))
will always return true or false. It won't block. That's the behavior of ConcurrentDictionary. It will return false if the key is not in the dictionary.
If you're looping while that method returns false and it's stuck, that means that the item isn't in the dictionary when the loop begins. Either it either was never in the dictionary or that another thread already removed it.
Is your intention to loop until the item is not in the dictionary?
You could try this:
if (!knownSpecificationBag.TryRemove(AS400SpecificationAttributeWork, out tmpstr)
&& !knownSpecificationBag.ContainsKey(AS400SpecificationAttributeWork))

Implement proper equals and gethashcode when using TryRemove
public override int GetHashCode()
{
return new { this.name, this.value, this.group, this.productNumber }.GetHashCode();
}
public bool Equals(AS400SpecificationAttribute other)
{
if (other == null)
return false;
return (this.ProductNumber.Equals(other.productNumber) && ((this.group != null && this.group.Equals(other.AttributeGroup)) || (this.group == null && other.AttributeGroup == null)) && ((this.name!= null && this.name.Equals(other.AttributeName)) || (this.name == null && other.AttributeName == null)) && ((this.value != null && this.value.ToUpper().Equals(other.AttributeValue.ToUpper())) || (this.value == null && other.AttributeValue == null)));
}

C# for case in string(easy)

so I have this code. I need to generate a for loop that checks all the characters in the string and checks if they are all valid(So numbers from 0->7). But I don't know how to write it, I tried something but it didn't work. Here are the examples:user enters: 77, code works, user enters 99, code doesn't work, user enters 5., code doesn't work, etc..
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace NALOGA1
{
class Program
{
static string decToOct(int stevilo)//v mojon primere 7
{
string izhod = "";
//7>0 DRŽI
while (stevilo > 0)
{
//izhodi se dodeli ostanek deljenja z 8 keri se spremeni v string
izhod = (stevilo % 8) + izhod;
//7/8;
stevilo /= 8;
}
return izhod;
}
static int Octtodesetisko(string stevilo)
{
double vsota = 0;
for (int i = stevilo.Length - 1; i >= 0; i--)
{
int stevka = stevilo[i] - '0';
vsota += (stevka * Math.Pow(8, i));
}
return (int)vsota;
}
static void Main(string[] args)
{
//3 podprogram-in progress
string prvastevilka = Console.ReadLine();
int prvasprememba = Int32.Parse(prvastevilka);
if (prvasprememba > 0)
{
Console.WriteLine(decToOct(prvasprememba));
}
else
{
Console.WriteLine("Napaka");
}
string drugastevilka = Console.ReadLine();
int drugasprememba = Octtodesetisko(drugastevilka);
foreach (char znak in drugastevilka)
{
if(znak!=1 || znak!=2 || znak!=3 || znak!=4 || znak!=5 || znak!=6 || znak!=7)
{
Console.WriteLine("Napaka");
}
else
{
Console.WriteLine("dela :D");
}
}
Console.ReadKey();
}
}
}

Personally, I would take advantage of the LINQ Enumerable.All method to express this in a very concise and readable way:
if (str.Any() && str.All(c => c >= '0' && c <= '7'))
{
Console.WriteLine("good");
}
else
{
Console.WriteLine("bad");
}
EDIT: No LINQ
It's not hard to translate what the LINQ Enumerable.All method does to a normal loop. It's just more verbose:
bool isValid = true;
foreach (char c in str)
{
if (c < '0' || c > '7')
{
isValid = false;
break;
}
}
if (str.Length != 0 && isValid)
{
Console.WriteLine("good");
}
else
{
Console.WriteLine("bad");
}

Firstly, there seems to be a mistake in the line
if(znak!=1 || znak!=2 || znak!=3 || znak!=4 || znak!=5 || znak!=6 || znak!=7)
I guess it should read
if(znak!='1' || znak!='2' || znak!='3' || znak!='4' || znak!='5' || znak!='6' || znak!='7')
which should be compressed to
if (znak >= '0' && znak <= '7')
You can use linq instead of the for loop here like this:
if (drugastevilka.All(c => c >= '0' && c <= '7')
Console.WriteLine("dela :D");
else
Console.WriteLine("Napaka");
But the best solution is probably to use a regular expression:
Regex regex = new Regex("^[0-7]+$");
if (regex.IsMatch(drugastevilka))
Console.WriteLine("dela :D");
else
Console.WriteLine("Napaka");
Edit: the linq solution shown accepts empty strings, the regex (as shown) needs at least 1 character. Exchange the + with a * and it will accept empty strings, too. But I don't think you want to accept empty strings.

You are messing up with the datatype
Can you try with below code
static string decToOct(int stevilo)//v mojon primere 7
{
int izhod = 0;
//7>0 DRŽI
while (stevilo > 0)
{
//izhodi se dodeli ostanek deljenja z 8 keri se spremeni v string
izhod = (stevilo % 8) + izhod;
//7/8;
stevilo /= 8;
}
return (izhod.ToString());
}

What about something like this?
class Program
{
static void Main(string[] args)
{
string someString = "1234567";
string someOtherString = "1287631";
string anotherString = "123A6F2";
Console.WriteLine(IsValidString(someString));
Console.WriteLine(IsValidString(someOtherString));
Console.WriteLine(IsValidString(anotherString));
Console.ReadLine();
}
public static bool IsValidString(string str)
{
bool isValid = true;
char[] splitString = str.ToCharArray(); //get an array of each character
for (int i = 0; i < splitString.Length; i++)
{
try
{
double number = Char.GetNumericValue(splitString[i]); //try to convert the character to a double (GetNumericValue returns a double)
if (number < 0 || number > 7) //we get here if the character is an int, then we check for 0-7
{
isValid = false; //if the character is invalid, we're done.
break;
}
}
catch (Exception) //this will hit if we try to convert a non-integer character.
{
isValid = false;
break;
}
}
return isValid;
}
}
IsValidString() takes a string, converts it to a Char array, then checks each value as such:
Get the numeric value
Check if the value is between 0-7
GetNumericValue will fail on a non-integer character, so we wrap it in a try/catch - if we hit an exception we know that isValid = false, so we break.
If we get a valid number, and it's not between 0-7 we also know that isValid = false, so we break.
If we make it all the way through the list, the string is valid.
The sample given above returns:
IsValidString(someString) == true
IsValidString(someOtherString) == false
IsValidString(anotherString) == false

If statement not working C#

I'm not sure if I'm just really tired and missing something obvious or there is something wrong with my program. Basically my if statement condition is not working.
public bool check(string nextvaluebinary)
{
bool test = true;
for (int i = -1; i < 8; ++i)
{
i++;
System.Console.WriteLine(nextvaluebinary[i] + " " + nextvaluebinary[i + 1]);
if (nextvaluebinary[i] == 1)
{
System.Console.WriteLine("Activated");
if (nextvaluebinary[i + 1] == 0)
{
test = false;
System.Console.WriteLine("false");
}
}
else
{
test = true;
}
if (test == false)
{
break;
}
}
return test;
}
I'm passing in the string 0001010110 and im getting an output of:
0 0
0 1
0 1
0 1
1 0
but no "activated" or "false" even though the last one is "1 0". Again sorry if this is a dumb question and any insight or help would be greatly appreciated.

You're comparing a char against an int. The check you're attempting carries a completely different meaning than what you're trying to accomplish. You need to either check if its equal to '1' or cast the char to an int first so you can do a numeric comparison.
if (nextvaluebinary[i] == '1')

Since nextvaluebinary is a String, this comparison will succeed only if that string has a null character, i.e. '\0':
if (nextvaluebinary[i + 1] == 0)
It looks like you are looking for a zero digit character, instead, so you should write
if (nextvaluebinary[i + 1] == '0')

Equals is used with char to int. So that will use char code.
Use this
public static bool check(string nextvaluebinary)
{
bool test = true;
for (int i = -1; i < 8; ++i)
{
i++;
System.Console.WriteLine(nextvaluebinary[i] + " " + nextvaluebinary[i + 1]);
if (nextvaluebinary[i] == '1')
{
System.Console.WriteLine("Activated");
if (nextvaluebinary[i + 1] == '0')
{
test = false;
System.Console.WriteLine("false");
}
}
else
{
test = true;
}
if (test == false)
{
break;
}
}
return test;
}

Convert String To Int in LINQ

I have a LINQ query that queries a DataTable. In the DataTable, the field is a string and I need to compare that to an integer, basically:
if ((electrical >= 100 && electrical <= 135) || electrical == 19)
{
// The device passes
}
the problem is, I am trying to do this in LINQ like this:
var eGoodCountQuery =
from row in singulationOne.Table.AsEnumerable()
where (Int32.Parse(row.Field<String>("electrical")) >= 100 &&
Int32.Parse(row.Field<String>("electrical")) <= 135) &&
Int32.Parse(row.Field<String>("electrical")) != 19 &&
row.Field<String>("print") == printName
select row;
I keep getting the exception:
Input string was not in a correct format
The main problem occurs when electrical == ""

Unfortunately, the framework doesn't provide a nice clean way to handle parsing scenarios where it fails. Of what's provided, they only throw exceptions or use out parameters, both of which does not work well with linq queries. If any one value you're parsing fails, the entire query fails and you just can't really use out parameters. You need to provide a method to handle the parsing without that does not throw and does not require using out parameters.
You can handle this in many ways. Implement it where upon failure, you return some default sentinel value.
public static int ParseInt32(string str, int defaultValue = 0)
{
int result;
return Int32.TryParse(str, out result) ? result : defaultValue;
}
Or what I would recommend, return a nullable value (null indicating it failed).
public static int? ParseInt32(string str)
{
int result;
return Int32.TryParse(str, out result) ? result : null;
}
This simplifies your query dramatically while still leaving it readable.
public bool GetElectricalStatus(string printName)
{
var query =
from row in singulationOne.Table.AsEnumerable()
where row.Field<string>("print") == printName
// using the nullable implementation
let electrical = ParseInt32(row.Field<string>("electrical"))
where electrical != null
where electrical == 19 || electrical >= 100 && electrical <= 135
select row;
return !query.Any();
}
p.s., your use of the Convert.ToInt32() method is incorrect. It is the same as calling Int32.Parse() and does not return a nullable, it will throw on failure.

I would check if the data in the column does not contain leading/trailing whitespaces - i.e. "15 " rather than "15" and if it does (or might do) trim it before trying to convert:
Int32.Parse(row.Field<String>("electrical").Trim())
BTW: not related to the error but I'd use let statement to introduce a local variable and do the conversion once:
let x = Int32.Parse(row.Field<String>("electrical").Trim())
where x >= 100...

I could not get anything to work, so I re-did the whole method:
public bool GetElectricalStatus(string printName)
{
List<object> eGoodList = new List<object>();
var eGoodCountQuery =
from row in singulationOne.Table.AsEnumerable()
where row.Field<String>("print") == printName
select row.Field<String>("electrical");
foreach (var eCode in eGoodCountQuery)
{
if (!string.IsNullOrEmpty(eCode.ToString()))
{
int? eCodeInt = Convert.ToInt32(eCode);
if (eCodeInt != null &&
(eCodeInt >= 100 && eCodeInt <= 135) || eCodeInt == 19)
{
eGoodList.Add(eCode);
}
}
}
if (eGoodList.Count() > 0)
{
return false;
}
else
{
return true;
}
}
The main problem occurs when electrical == ""

Why not make a function that does your evaluation, and call it in your Linq query. Put logic in to check the validity of the data contained within (so if you can't parse the data, it should return false)...
The function:
bool IsInRange(string text, int lower, int upper, params int[] diqualifiers)
{
int value = int.MinValue;
if (!int.TryParse(text, out value)) {
return false;
}
if (!(value >= lower && value <= upper)) {
return false;
}
if (disqualifiers != null && disqualifiers.Any(d => d == value)) {
return false;
}
return true;
}
The Linq query...
var eGoodCountQuery =
from row in singulationOne.Table.AsEnumerable()
where
IsInRange(row.Field<String>("electrical"), 100, 135, 19)
&& row.Field<String>("print") == printName
select row;