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  • infix operation to postfix using stacks

    - by Chris De La O
    We are writing a program that needs to convert an infix operation (4 5/3) to postfix (4 5 3 / ) using stacks. however my convert to postfix does not work as it doesnt not output the postFix array that is supposed to store the conversion from infix notation to postfix notation. here is the code for the convertToPostix fuction. //converts infix expression to postfix expression void ArithmeticExpression::convertToPostfix(char *const inFix, char *const postFix) { //create a stack2 object named cow Stack2<char> cow; cout<<postFix; char thing = '('; //push a left parenthesis onto the stack cow.push(thing); //append a right parenthesis to the end of inFix array strcat(inFix, ")"); int i = 0;//declare an int that will control posFix position //if the stack is not empty if (!cow.isEmpty()) { //loop to run until the last character in inFix array for (int x = 0; inFix[x]!= '\0'; x++ ) { //if the inFix element is a digit if (isdigit(inFix[x])) { postFix[i]=inFix[x];//it is assigned to the next element in postFix array i++;//move on to next element in postFix } //if the inFix element is a left parenthesis else if (inFix[x]=='(') { cow.push(inFix[x]);//push it unto the stack } //if the inFix element is an operator else if (isOperator(inFix[x])) { char oper2 = inFix[x];//char variable holds inFix operator if (isOperator(cow.stackTop()))//if the top node in the stack is an operator { while (isOperator(cow.stackTop()))//and while the top node in the stack is an operator { char oper1 = cow.stackTop();//char variable holds node operator if(precedence( oper1, oper2))//if the node operator has higher presedence than node operator { postFix[i] = cow.pop();//we pop such operator and insert it in postFix array's next element cow.push(inFix[x]);//and push inFix operator unto the stack i++;//move to the next element in posFix } } } //if the top node is not an operator //we push the current inFix operator unto the top of the stack else cow.push(inFix[x]); } //if the inFix element is a right parenthesis else if (inFix[x]==')') { //we pop everything in the stack and insert it in postFix //until we arrive at a left paranthesis while (cow.stackTop()!='(') { postFix[i] = cow.pop(); i++; } //we then pop and discard left parenthesis cow.pop(); } } postFix[i]='\0'; //print !!postFix array!! (not stack) print();//code for this is just cout<<postFix; }

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  • Haskell: Gluing a char and a list together?

    - by Vincent
    So I have this code here: toWords :: String - [a] toWords "" = [] toWords (nr1 : rest) | nr1 == ' ' = toWords rest | otherwise = nr1 : toWords rest The "toWords" function should simply remove all spaces and return a list with all the words. But I keep getting this error: test.hs:5:18: Couldn't match expected type a' against inferred typeChar' `a' is a rigid type variable bound by the type signature for `toWords' at test.hs:1:22 In the first argument of `(:)', namely `nr1' In the expression: nr1 : toWords rest In the definition of `toWords': toWords (nr1 : rest) | nr1 == ' ' = toWords rest | otherwise = nr1 : toWords rest Failed, modules loaded: none.

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  • Using RegEx to Identify parts of a Database Connection String

    - by David_Jarrett
    I'm trying to get to grips with regular expressions: I have a database connection string and I'd like to use a regular expression to identify specific Keys and Values within it. For example server=foo;database=bar;uid=foo;pwd=bar I'd like something to return "database=bar;" using the 'database' key to identify it, ideally it would be case insensitive. I can do this using normal code, but I think that this is exactly the sort of thing for which regular expressions were designed.

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  • validation of special characters

    - by jpallavi
    I want to validate login name with special characters !@#S%^*()+_-?/<:"';. space using regular expression in ruby on rails. These special characters should not be acceptable. What is the code for that? Thanks, Pallavi

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  • Engineering techniques to diminish MVVM Driven Development time?

    - by Oscar Cabrero
    Hi Currently we just start releasing modules for a big project in MVVM but seems like the deliverables are starting to encounter a slowness with this model, such things as the learning curve effort and the fact that mvvm do requires a bit more code than other patterns, What Programming and software engineering techniques do you employ or thing could help us reduce the effort and speed up development? things like code generation with T4 templates, ligth MVVM frameworks, use Expression Blend, hire a designer to hanle UX. Thanks for any advice you could provide.

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  • Checking an empty Core Data relationship (SQLite)

    - by rwat
    I have a to-many relationship in my data model, and I'd like to get all the objects that have no corresponding objects in the relationship. For example: Customer - Purchases I want to get all Customers that have 0 Purchases. I've read somewhere that I could use "Purchases[SIZE] = 0", but this gives me an unsupported function expression error, which I think means it doesn't work with a SQLite backing store (which I don't want to switch from, due to some performance constraints). Any ideas?

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  • Big-O complexity of c^n + n*(logn)^2 + (10*n)^c

    - by zebraman
    I need to derive the Big-O complexity of this expression: c^n + n*(log(n))^2 + (10*n)^c where c is a constant and n is a variable. I'm pretty sure I understand how to derive the Big-O complexity of each term individually, I just don't know how the Big-O complexity changes when the terms are combined like this. Ideas? Any help would be great, thanks.

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  • Regex for Eclipse/Flash Builder File Search for comments?

    - by Brian Bishop
    In Eclipse (and Flash/Flex Builder) you get the option with Ctrl+Shift+F to do a file search and look for a regular expression. Would be a real handy thing to know. I want to find the word negate if it appears in a Flex/java comment like the following: // It was negated because or /* The negate option was.... */ or /** * We have to negate the value */ Any ideas? Will test them out at http://www.regexplanet.com/simple/index.html

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  • One-liner javascript to collect values from object graph?

    - by Kevin Pauli
    Given the following object graph: { "children": [ { "child": { "pets": [ { "pet": { "name": "fido" } }, { "pet": { "name": "fluffy" } } ] } }, { "child": { "pets": [ { "pet": { "name": "spike" } } ] } } ] } What would be a nice one-liner (or two) to collect the names of my grandchildren's pets? The result should be ["fido", "fluffy", "spike"] I don't want to write custom methods for this... I'm looking for something like the way jQuery works in selecting dom nodes, where you can just give it a CSS-like path and it collects them up for you. I would expect the expression path to look something like "children child pets pet name"

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  • eregi replace replacement

    - by apis17
    hi, since eregi replace was deprecated on version 5.3 i want to make my program compatible with new version of php http://php.net/manual/en/function.eregi-replace.php so, i'm trying to use preg_replace like this preg_replace(",",'','20,000.00'); but come with error i'm familiar with eregi_replace(',','','20,000.00'); i'm not familiar with regex expression. what is the best replacement for eregi_replace?

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  • How can I match a match a null byte (0x00) in the Visual Studio binary editor with a find using a re

    - by Paul K
    Open a file in the Visual Studio binary editor that contains a null byte (0x00), then use the Quick Find feature (Ctrl +F) to find null bytes. I would have thought I could use a regular expression such as \x00 to match null bytes but it doesn't work. Searching for any other hex value using this method works fine. Is this a VS bug, 'feature', or am I just missing something? Is there a work around?

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  • i tried to implement tde in sql2008...n got the error below.....plz help me to resolve...

    - by mahima
    while using USE mssqltips_tde; CREATE DATABASE ENCRYPTION KEY with ALGORITHM = AES_256 ENCRYPTION BY SERVER CERTIFICATE TDECert GO getting error Msg 156, Level 15, State 1, Line 2 Incorrect syntax near the keyword 'KEY'. Msg 319, Level 15, State 1, Line 3 Incorrect syntax near the keyword 'with'. If this statement is a common table expression or an xmlnamespaces clause, the previous statement must be terminated with a semicolon. please help in resolving the same as i need to implement Encryption on my DB

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  • RegEx to reverse order of list?

    - by quantomcat
    Is there a singular regular expression that can be used in, say, a text editor's search/replace dialog to reverse the order of the items in a list? For instance, take this list: First item Second item Third item Select it in a text editor like EditPad, bring up the search and replace box, apply a regex (run as a loop or not) and turn it into: Third item Second item First item Can this be done?

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  • DRY-ing very similar specs for ASP.NET MVC controller action with MSpec (BDD guidelines)

    - by spapaseit
    Hi all, I have two very similar specs for two very similar controller actions: VoteUp(int id) and VoteDown(int id). These methods allow a user to vote a post up or down; kinda like the vote up/down functionality for StackOverflow questions. The specs are: VoteDown: [Subject(typeof(SomeController))] public class When_user_clicks_the_vote_down_button_on_a_post : SomeControllerContext { Establish context = () => { post = PostFakes.VanillaPost(); post.Votes = 10; session.Setup(s => s.Single(Moq.It.IsAny<Expression<Func<Post, bool>>>())).Returns(post); session.Setup(s => s.CommitChanges()); }; Because of = () => result = controller.VoteDown(1); It should_decrement_the_votes_of_the_post_by_1 = () => suggestion.Votes.ShouldEqual(9); It should_not_let_the_user_vote_more_than_once; } VoteUp: [Subject(typeof(SomeController))] public class When_user_clicks_the_vote_down_button_on_a_post : SomeControllerContext { Establish context = () => { post = PostFakes.VanillaPost(); post.Votes = 0; session.Setup(s => s.Single(Moq.It.IsAny<Expression<Func<Post, bool>>>())).Returns(post); session.Setup(s => s.CommitChanges()); }; Because of = () => result = controller.VoteUp(1); It should_increment_the_votes_of_the_post_by_1 = () => suggestion.Votes.ShouldEqual(1); It should_not_let_the_user_vote_more_than_once; } So I have two questions: How should I go about DRY-ing these two specs? Is it even advisable or should I actually have one spec per controller action? I know I Normally should, but this feels like repeating myself a lot. Is there any way to implement the second It within the same spec? Note that the It should_not_let_the_user_vote_more_than_once; requires me the spec to call controller.VoteDown(1) twice. I know the easiest would be to create a separate spec for it too, but it'd be copying and pasting the same code yet again... I'm still getting the hang of BDD (and MSpec) and many times it is not clear which way I should go, or what the best practices or guidelines for BDD are. Any help would be appreciated.

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  • OGNL thread safety

    - by Dewfy
    I'm going to reuse OGNL library out of Struts2 scope. I have rather large set of formulas, that is why I would like to precompile all of them: Ognl.parseExpression(expressionString); But I'm not sure if precompiled expression can be used in multi-thread environment. Does anybody knows if it can be used?

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  • How to replace only part of the match with python re.sub

    - by Arty
    I need to match two cases by one reg expression and do replacement 'long.file.name.jpg' - 'long.file.name_suff.jpg' 'long.file.name_a.jpg' - 'long.file.name_suff.jpg' I'm trying to do the following re.sub('(\_a)?\.[^\.]*$' , '_suff.',"long.file.name.jpg") But this is cut the extension '.jpg' and I'm getting long.file.name_suff. instead of long.file.name_suff.jpg I understand that this is because of [^.]*$ part, but I can't exclude it, because I have to find last occurance of '_a' to replace or last '.' Is there a way to replace only part of the match?

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  • What's the best way to aggregate the boolean values of a Python dictionary?

    - by Thierry Lam
    For the following Python dictionary: dict = { 'stackoverflow': True, 'superuser': False, 'serverfault': False, 'meta': True, } I want to aggregate the boolean values above into the following boolean expression: dict['stackoverflow'] and dict['superuser'] and dict['serverfault'] and dict['meta'] The above should return me False. I'm using keys with known names above but I want it to work so that there can be an infinite number of unknown key names.

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  • Way to partialy match a Ruby string using Regexp

    - by Fabiano PS
    I'm working on 2 cases: assume I have those var: a = "hello" b = "hello-SP" b = "not_hello" 1 - Any partial matches I want to accept any string that has the var a inside, so b and c would match. 2 - Patterned match I want to match a string that has a inside, followed by '-', so b would match, c does not. I am having problem, because I always used the syntax /expression/ to define Regexp, so how dinamicaly define an RegExp on Ruby??

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