Questions about data comparison and efficient ways to accomplish it.

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20
votes
7answers
590 views

Why do most mainstream languages not support “x < y < z” syntax for 3-way Boolean comparisons?

If I want to compare two numbers (or other well-ordered entities), I would do so with x < y. If I want to compare three of them, the high-school algebra student will suggest trying x < y < ...
0
votes
3answers
95 views

How to effectively compare the (almost) same code which has been auto-formatted?

I am trying to infer the differences between two projects, however so far it has been really painful, because one of the parties has done auto-formatting on the code. Basically, this makes a merging ...
18
votes
3answers
9k views

How is Node.js different from other server-side frameworks?

I've noticed that Node.js has become very popular, and I've seen several instances of people doing small-scale projects in it. I've also looked at pros and cons lists to get an idea of what Node.js ...
49
votes
3answers
7k views

What are the biggest differences between F# and Scala?

F# and Scala are both functional programming langugages that don't force the developer to only use immutable datatypes. They both have support for objects, can use libraries written in other languages ...
7
votes
2answers
304 views

Efficient algorithm to merge n successive sorted arrays in place

I am developing an in-place sorting algorithm that leaves the array into a state where it is basically a succession of sorted subsequences of any size (most are bigger than log2(size(array))); then it ...
0
votes
1answer
13 views

Comparing articles from various web-stores

Today I had the idea to write a program that compares the prizes between different web-stores. The key question I am asking myself is how to find (with a high probability) the same article on another ...
4
votes
4answers
188 views

Avoiding Division by Zero Using Float Comparison

Source code analyzers (like SonarQube) complain about float (or double) equality comparisons because equality is a tricky thing with floats; the values compared can be the results of computations ...
22
votes
2answers
11k views

Algorithm to merge two sorted arrays with minimum number of comparisons

Given are two sorted arrays a, b of type T with size n and m. I am looking for an algorithm that merges the two arrays into a new array (of maximum size n+m). If you have a cheap comparison ...
0
votes
1answer
115 views

Comparison Function Returns True or False

In my python CS class at school, we were given a true or false question as follows. A comparison function returns either True or False. When originally answering I thought about two things. ...
2
votes
3answers
193 views

Functional programming: Compare all items in an array

In functional programming, how do I do an equality comparison of all items in an array? I have an array of items that I want to compare, for example for equality. Is it possible to use a fold (also ...
25
votes
5answers
2k views

Could an instance be equal to some other instance of a more specific type?

I've read this article: How to Write an Equality Method in Java. Basically, it provides a solution for an equals() method that supports inheritance: Point2D twoD = new Point2D(10, 20); Point3D ...
1
vote
2answers
118 views

Multi-pattern matching

I have a given byte array in C and I need to match it against several byte arrays and return true if there is any match. I can make various memcmp's but I feel that it is very inefficient. Do you ...
1
vote
4answers
661 views

List comparing techniques for faster performance

I need to cross names from two lists, and find all occurrences of one name in the other. The lists are too big, one have 50k elements and the other 400k. For a small list I would use two foreach ...
0
votes
0answers
116 views

Algorithm to maximize pairwise comparisons using transitive property

I'm looking for some direction on building an algorithm that will maximize the number of pairwise comparisons of objects in a set using transitivity. To explain in detail: Suppose there are x ...
1
vote
3answers
4k views

Java Web Frameworks (JSF vs Wicket) Third-party component suites in Wicket?

A presentation linked in an answer here demonstrated a comparison of several web development frameworks. It was a good comparison but caused me a little worry based on the technology stack that I ...
3
votes
3answers
142 views

Determine frequency-range that matches closest to input list of frequencies

Since this question is not about "code not working", I'm asking my first question here instead of StackOverflow. Inform me if any required information is missing from the question. Setup: I ...
4
votes
4answers
472 views

Why are return values from compare functions in many languages defined loosely?

Many languages define that compare functions should return ANY negative value, zero, or ANY positive value. Is there some reason that it shouldn't be clearly defined as -1 0 and 1? Does a wide range ...
2
votes
4answers
3k views

How do you find the first common element in two arrays

How do you find the first common element in two arrays? My attempt: I looped through each at the same time and add the current value to a separate set for each of the lists. Also, check if the ...
0
votes
2answers
311 views

Comparing doubles [duplicate]

I need to compare to double variables like this if (distance <= radius) both distance and radius are doubles and I remember in class how to use epsilon comparisons for checking equality but how ...
0
votes
1answer
145 views

Should a comparison method ever return the same type back as it's comparing?

First, this is homework, but no, I'm not asking for anyone to do any code for me. My course start date isn't for another month (it's online), so I can't ask for clarification. I thought I'd see if ...
4
votes
4answers
385 views

Legitimate cases of having .equals() behaving inconsistently with .compareTo()?

Java documentation says it's "strongly recommended" to have them behaving consistently. But are there legitimate cases of java/c#/python/etc Object.equals() method behaving inconsistently with the ...
0
votes
0answers
146 views

Compare names and the use of Levenshtein's algorithm

I need to cross names from two lists. What is the best away to compare the names? As you may expect, in one list we can have the complete name, on the other just the first and last. Besides that, ...
0
votes
3answers
365 views

Is JavaScript fail-safe?

I was compiling a list of comparison of top 10 programming languages (JavaScript included). I was doing it from this Wikipedia page. However, in the third table (Failsafe I/O), there is no row for ...
37
votes
10answers
26k views

What's the difference between a “developer” and a “programmer”? [duplicate]

Possible Duplicate: What are the key differences between software engineers and programmers? What is the difference between software engineer and software developer? What's the difference ...
2
votes
1answer
42 views

Comparing path strings against list of rules

I am trying to find a way to enhance a filtering algorithm. I am developing a backup software that enables users to specify custom filters to exclude unwanted files/directories. Currently when trying ...
102
votes
5answers
49k views

How can Swift be so much faster than Objective-C in these comparisons?

Apple launched its new programming language Swift at WWDC14. In the presentation, they made some performance comparisons between Objective-C and Python. The following is a picture of one of their ...
52
votes
6answers
5k views

Dynamically vs Statically typed languages studies

Do there exist studies done on the effectiveness of statically vs dynamically typed languages? In particular: Measurements of programmer productivity Defect Rate Also including the effects of ...
-2
votes
1answer
195 views

Why are mostly 9999, 99999… are used for making comparisons [closed]

I (I am sure everyone else also) have always seen comparisons of some value to 999 or 9999 .... etc. for e.g.: in CSS z-index: 9999 or some times str.length < 99999 I wonder if there is some ...
6
votes
5answers
321 views

Algorithm to test file equivalence

I'm writing a program that needs to test if a file is equivalent to one or more other files. To accomplish this, every time we see a new file we stat the file and get the size. We use the size as a ...
23
votes
1answer
11k views

What are the main advantages and disadvantages of LL and LR parsing?

When building a parser to a programming language what I earn and what I lost choosing one or the other?
1
vote
4answers
2k views

When to use identity comparison instead of equals?

I wonder why would anybody want to use identity comparison for fields in equals, like here (Java syntax): class C { private A a; public boolean equals(Object other) { // standard ...
5
votes
2answers
434 views

Is there any language-agnostic specification for “String Natural Sorting Order”

As I painfully try to find a good natural sorting algorithm written in JavaScript I then stumble upon a bunch of different implementations, & interesting blog posts & answers on Stack ...
0
votes
2answers
191 views

Finding metrics for development time in different languages [closed]

I'm trying to determine if a language I'm investigating (Groovy) is better for developing enterprise applications than our current language (Java). Specifically I'm trying to figure out if it will ...
0
votes
1answer
127 views

comparison of an unsigned variable to 0

When I execute the following loop : unsigned m; for( m = 10; m >= 0; --m ){ printf("%d\n",m); } the loop doesn't stop at m==0, it keeps executing interminably, so I thought that ...
0
votes
2answers
446 views

Comparing two software versions in C#

I´m working on a mod update checker for minecraft, but there is a big problem: The modders and online database that I´m using for update checks has no standard software versions e.g.: Local: ...
0
votes
1answer
55 views

How to develop a product compare page

I want to develop a product comparison page, where a user can compare 2 or 3 products. I was thinking about a 3 column list displaying every specification. But I want to highlight the differences. I ...
3
votes
2answers
320 views

Comparison of languages by usage type? [closed]

Does anyone know of a good place to go find comparisons of programming languages by the intended platform/usage? Basically, what I want to know, is of the more popular languages, which ones are meant ...
2
votes
2answers
322 views

How to (or should I) have one assert per test with object comparisons? [duplicate]

I've recently read The Art of Unit Testing by Roy Osherove which I found very useful for helping me establish how to define a good unit test. One key aspect of the guidelines Roy puts forward are to ...
0
votes
2answers
166 views

How to choose between different open-source libraries? [closed]

Recently, I found multiple GitHub repositories that would allow me to perform the same task. (In my case, assess the readability of text strings.) It made me wonder, what are the best practices for ...
3
votes
6answers
987 views

Why is PHP's method of comparing different types bad?

I'm working on designing a new programming language and trying to decide how I will do variable comparisons. Along with many different types of languages, I've used PHP for years and personally had ...
3
votes
4answers
2k views

Shallow or deep equal, which one is idiomatic in Java?

I have a domain model in which I use a few aggregation relations, i.e. an object of class A contains zero or more objects of class B. I use Java for the implementation and I represent such an ...
34
votes
7answers
23k views

What ASP.NET MVC can do and Ruby on Rails can't? [closed]

ASP.NET MVC and Rails have similar area of use, are built around same architecture, both frameworks are relatively new and open source. So as a Rails programmer I'd like to know, what ASP.NET MVC can ...
13
votes
1answer
1k views

Scala as a language for Generic Programming

In the paper “An Extended Comparative Study of Language Support for Generic Programming” by Garcia et al. an interesting comparison of programming languages features for generic programming is given: ...
26
votes
10answers
3k views

Is there any reason why most programming languages don't have '!>' (not greater than) and '!<' (not less than) operators?

I wonder if there is any reason - or if it is just an accident of history - that there are no !> and !< operators in most programming languages? a >= b (a greater OR equals b) could be ...
7
votes
2answers
506 views

Is Free Pascal just an open source, multi-platform clone of Turbo Pascal & Delphi?

Does Free Pascal introduce any significant language features over Turbo Pascal & then Delphi, or does it just introduce the Turbo Pascal & Delphi flavors of Pascal to more platforms?
3
votes
3answers
486 views

Which is the better: a <= b or a < b+1 [closed]

For loops are usually inclusice, exclusive, meaning that you start at the bottom, and stops when you reach, but don't to the top. In Python: for i in range(0,a): print(i) would print 0 through ...
5
votes
3answers
202 views

Importance of diffing and merging for design specifications documentation

The context of this question is choosing tools for writing design specifications for software projects. These documents will be written and maintained by architects and developers, I'm not talking ...
13
votes
2answers
594 views

Trying to understand the 2N lnN compares for quicksort

I was going through the analysis of quicksort in Sedgewick's Algorithms book. He creates the following recurrence relation for number of compares in quicksort while sorting an array of N distinct ...
4
votes
4answers
327 views

What security practices should you be aware of when writing software? [closed]

What different types of security do there exist? Why and when should they be implemented? Example: SQL Injection Prevention
2
votes
5answers
262 views

Best practice to sort then reverse, or write “backwards” comparator?

I wrote a comparator for a custom class of mine and when I ran my code I realised the output of my list of these objects was in the reverse order as to what I wanted. It was "ascending" as opposed to ...