What is the cause? The error message is pretty clear: you’re trying to access a file, and it’s not accessible because another process (or even the same process) is doing something with it (and it didn’t allow any sharing). Debugging It may be pretty easy to solve (or pretty hard to understand), depending on your … Read more
The maximum number of days in a year is 366, this gives us 52 full weeks. In those 52 weeks there are at least 52 * 5 = 260 weekdays. We are left with 2 days (52 * 7 = 364), it is possible that these 2 days are weekdays. So maximum number of weekdays … Read more
The Abstact data type Wikipedia article has a lot to say. In computer science, an abstract data type (ADT) is a mathematical model for a certain class of data structures that have similar behavior; or for certain data types of one or more programming languages that have similar semantics. An abstract data type is defined indirectly, only … Read more
Developers are often confused by what a callback is because of the name of the damned thing. A callback function is a function which is: accessible by another function, and is invoked after the first function if that first function completes A nice way of imagining how a callback function works is that it is … Read more
First and foremost, the “pass by value vs. pass by reference” distinction as defined in the CS theory is now obsolete because the technique originally defined as “pass by reference” has since fallen out of favor and is seldom used now.1 Newer languages2 tend to use a different (but similar) pair of techniques to achieve the same effects (see below) which … Read more
Consider a simple function that adds the first N natural numbers. (e.g. sum(5) = 0 + 1 + 2 + 3 + 4 + 5 = 15). Here is a simple JavaScript implementation that uses recursion: If you called recsum(5), this is what the JavaScript interpreter would evaluate: Note how every recursive call has to complete before … Read more
The stack is the memory set aside as scratch space for a thread of execution. When a function is called, a block is reserved on the top of the stack for local variables and some bookkeeping data. When that function returns, the block becomes unused and can be used the next time a function is … Read more
Dependency Injection is passing dependency to other objects or framework( dependency injector). Dependency injection makes testing easier. The injection can be done through constructor. SomeClass() has its constructor as following: Problem: If myObject involves complex tasks such as disk access or network access, it is hard to do unit test on SomeClass(). Programmers have to … Read more
In computing, an idempotent operation is one that has no additional effect if it is called more than once with the same input parameters. For example, removing an item from a set can be considered an idempotent operation on the set. In mathematics, an idempotent operation is one where f(f(x)) = f(x). For example, the … Read more
Introduction Object-Relational Mapping (ORM) is a technique that lets you query and manipulate data from a database using an object-oriented paradigm. When talking about ORM, most people are referring to a library that implements the Object-Relational Mapping technique, hence the phrase “an ORM”. An ORM library is a completely ordinary library written in your language … Read more