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Below is an example check list for Linux server hardening – All ports except SSH, http is blocked. On some of the servers, DNS and SMTP ports are open for name resolution and mail sending purposes. We have hardened the kernel to disable all the unnecessary services. This has been done at the kernel level…
C++ provides allocation and deallocation functions ‘new’ and ‘delete’ similar to the malloc() and free() function in C. The main advantage of dynamic allocation is that it allows us to automatically allocate enough memory to hold an object of the specified type and you don’t need to use the ‘sizeof’ operator. Also, you don’t need…
A reference is essentially an implicit pointer that acts as another name for an object. One important use for a reference is to allow you to create functions that automatically use call-by-reference parameter passing rather than C++’s default call-by-value method. When you create a reference parameter, that parameter automatically refers to (implicitly points to) the…
C++ supports implementation of array of objects. Below is a simple implementation of array of objects – Note that we polymorphic constructors that acts upon the array, and one of them acts upon the array index and assign it to the class member ‘i’. Notice that the class object prints 0 when the un-initialized array…
Static data members are used when only one copy of the variable exists and all the objects of that class share that variable. It is mostly used to synchronize various objects accessing a shared variable. Below is a simple C++ program representing this functionality – Static member functions could only access members of a class….
Inline functions are small functions defined with the inline keyword. The advantage of using inline functions are – They do not involve the usual stack operations as with ordinary function calls and returns, thus speeds up execution Usually used within classes which involves a lot of operations (small) on the private data It is professional…
When a function is declared as friend, it is not a member of any class. But it could access the private and protected parts of the class. freind2.cpp below shows a member function of one class declared as a friend of another class – Below are the advantages of using friend functions – in operator…
Structure is similar to Class except for the fact that in structure declaration, all the members are public otherwise specified as private. For example –
C++ provides a wide range of Keywords and much extensive than C programming offers. Below are the commonly used Keywords (reserved). alignas Used to precisely control the memory alignment of a user defined data/variable alignof returns in the alignment value in bytes of the specified type and bitwise AND operator and_eq equivalent to &= operator…
C++ also supports unions as in C. They are functionally similar to that of a class but has the following limitations: All members are public by default Cannot be a base class to inherit other classes Cannot have virtual functions Cannot include static variable An object using a constructor and destructor cannot be a member…
Constructor and Destructor functions are used in a class so as to automatically perform certain operations when an object of that class type is created and destroyed. For example, the constructor function named Stack() could be used to automatically initialize stktop = 0 when objects stack1 and stack2 are first executed. Similarly the destructor function…
Inheritance is the property of representing a base class and its derived classes as a hierarchy of classes with the most general functions of the class vested at the base or parent class and then specifying added qualities in each derived class. Below is an example of how we can represent a base class and…
C++ provides options to overload an operator with more than one function. For eg: C++ overloads the operators << and >> with functions of performing their original < and > operations and doing the console operations.
The principle of function overloading helps to implement polymorphism in C++ in which two or more functions share the same name (overloaded functions) and perform a general action but using different methods or approaches. The overloaded functions must differ in their function/method parameters/signatures and are defined and coded separately. They may or may not differ…
Classes are logical abstractions while Objects are instances of the classes that physical existence in the memory. Syntax for class declaration – We could use any number of access specifiers i.e, public, private, protected. But usually it is visually ordered if they are all grouped under only 3 headings. A class is instantiated as a…
C++ is/was and will be one of the classic and ever-green object oriented programming language built for the pure purpose of creating strongly typed, object oriented, secured and highly efficient programs. C++ was developed by Bjarne Stroustrup by blending C language (procedural) with the object oriented features of Simula67. The first draft of ANSI standard…
Ada, a descendent programming language mainly of Pascal, is a statically and strong typed, structured and imperative programming language that inherently supports pure object oriented programming, explicit concurrency and tasks, low level access to I/O and data representation, external interrupt handling, synchronous message passing, design by contract and non-deterministic programming techniques. Static Type checking checks…
Software metrics refers to measuring the software qualitatively and quantitatively so that we arrive at a perfect assessment of software quality and other attributes of the Software Product. McCall’s Qualitative metrics for assessing Software Quality The above diagram shows McCall’s software quality factors which may be used to assess software quality during product revision. Accordingly,…
The use of structured coding techniques and styles supports the primary goal of implementation to write quality source code and internal documentation that aid in easy verification with specification, debugging testing and modification. The source code thus generated will be simple, clear and elegant and less obscure, clever and complex. Structured coding techniques aids in…
Software Availability is defined as expected fraction of time for which a component or a system is functioning acceptably. If a program has a constant failure intensity ie. it is being operational without any changes or modifications or repairs, then Availability is calculated as the ratio – Availability = Uptime / Uptime + Downtime Here,…
Software Reliability Metrics relates to measurements made for assessing software reliability. Most of these software reliability metrics evolved from the earlier hardware reliability metrics. The following table gives the various Software Reliability metrics used, their definition and example system in which they can be applied. Software Reliability Metrics Definition Eg. Systems 1. POFOD – Probability…
Software Faults Software reliability depends heavily on defects in a software product and a repair activity undergone to correct them consequently as an entity to characterize these defects, Faults is used. Fault can be defined as defective, missing or extra instruction or set of relative instruction that is the cost of one or more actual…
The three of the most important Software product characteristics are – Quality, Cost and Schedule. Quantitative measures exist for cost and schedule. But quantification of Quality is difficult. The lack of quantitative measure for Quality is the main reason for quality problems in Software products. Reliability is the most important of characteristics inherent in the…
As you all know, Microsoft launched the latest version of its .NET platform by unifying all of its .NET flavors/platforms/frameworks. Its actually the 5.0 version of .NETCore 3.1. It will no longer be called .NETCore, but just .NET or with the version .NET 5.0. Microsoft took a huge leap with this release of .NET platform…
Fundamental concepts of Software design include Abstraction, Structure, Information hiding, Modularity, Concurrency and Verification. Abstraction – Abstraction is the intellectual tool which enables us to separate the conceptual aspects of the System. For eg: we may specify the FIFO property of a source or stack and functional characteristics of the routines (new, push, pop, top,…
Software Design is the process of creating the blueprint for the Software system being build. Generally, there are 3 major activities in Software Design – External Design Architectural Design Detailed Design The Architectural design and Detailed design are collectively known as Internal Design. External Design – External design involves conceiving, planning out and specifying the…
Estimating Software cost is an art. Software Sizing is important since the accuracy of the Software Project Estimation depends on – the extend to which the planner has properly estimated the size of the project to be built ability to translate the estimated product size (in terms of LOC or FP) into human effort, calendar…
.NETCore is the widely used cross-platform and open-source developer platform for building web/mobile/desktop/games/IoT/AI/ML apps. The future of .NET itself is set on one single flavor of .NETCore, specifically, the descendants of .NETCore 5.0. .NETCore 5.0 stable release is expected to be released November, 2020. This article is a handy reference to assist you with how…
As we all know, .NET is the widely used cross-platform and open-source developer platform for building web/mobile/desktop/games/IoT/AI/ML apps. As it evolved throughout the past few decades and present, it has mainly 3 flavors – Standard, Framework and Core. Out of these, majority of the apps are built using Framework flavor (4.x) and recent ones are…
We use ASP.NETCore UserIdentity a lot to implement and manage the User authentication mechanism for your website or application. Many times we don’t want the username field to be a valid email address and we don’t want to kick off the email confirmation process when we create user logins. This particularly makes sense when the logins…
Its useful for a Software Practitioner to understand the factors affecting Software Cost in order to arrive at close to perfect cost estimates. Most of these are classical factors and is true all the time as long as human write computer programmer in 0s and 1s. The various factors affecting Software cost estimation are as…
We have seen traditional and recently popular Software Development Team Structures. Now let us discuss on some specific team structures for the Programming or the Development team. Some of these are very traditional but still are very Generic in nature that will makes sense and could be extrapolated to various different variations. Selection of programming…
In this article we will start by reflecting upon some traditional software development team structures. This will help us appreciate where we came from. Some of these structures still exist in some of the traditional software development teams. Due to the intermingling nature of a Software Development Manager and a Software Project Manager, when you…
This article is written by wearing the traditional hat to appreciate where we came from. Water Fall or Phased approach to Software Development is the traditional approach in Software Engineering that has been proven for years to control and coordinate Software Development activities for a Scope fixed Software Product. Even though, presently we live in…
Software Engineering is the discipline that has historically studied, developed and is continuously improving methods, processes, techniques and frameworks to facilitate the analysis, design, development, implementation and enhancement and continuous evolution of Software Systems. The roots of first Software being written goes back to mid 1800’s when Ada Lovelace wrote the algorithm for the first…
If you take any Software Development environment, where a piece of code is written to automate a process, we can generalize the factors affecting Software Quality and developer productivity under 15 major heads – 1. Individual Ability – Since Software Development is a labor intensive activity, the individual ability of each of the project team member…
Computer Software or Software is an integral part of this Information Age which enables information collection, storage, processing and management of Information within machines or virtual machines or systems that assists humans. Software Engineering is a discipline which was conceptualized, developed and is constantly reviewed and evolved for planning , modelling, design, development, implementation and enhancement of this…
Given a weighted graph G, it is often desired to generate a spanning tree such that the sum of the weights of the tree edges is a minimum. Such a tree is called a Minimum Spanning Tree. Such a method is the cheapest way of connecting all nodes of G. Kurskal’s Algorithm Kurskal’s algorithm is a…
Depth first traversal of a Graph could be used to traverse a directed or un-directed graph and thus creating a spanning tree. Depth first traversal is a pre-order traversal of the given graph or spanning tree. The traversal starts from a node and traverses along the path until it reaches a node which has no…
Connected Graph A graph is said to be connected if there is a path between any two of its nodes. Cycle A Path from a node to itself is called a Cycle. A rgaph must require at least 3 nodes to form a cycle. Tree A Tree is a connected graph without cycles. Spanning Forests A…
There are many in-inadequacies in using the Adjacency Matrix representation of Graphs. Once such inadequacy is the difficulty in adding or deleting nodes while data is to be updated dynamically. Another inadequacy is that even if there exists no arc between two nodes, space must be reserved for the same in the array. Such inadequacies…
Flow Problem The main objective of a flow problem is to maximize the amount of an item being delivered from one point of a system to another. If we consider a water pipe system as shown below, our objective would be to maximize the amount of water flowing from source S to sink T. The…
Warshal’s Algorithm can be applied to find the Path Matrices and this the TRANSITIVE CLOSURE of a graph given its adj matrix. Warshal’s algorithm is based on the fact that the Pathk+1[i][j] is TRUE if and only if any one of the following conditions is true – 1) Pathk[i][j] == TRUE 2) Pathk[i][k+1] == TRUE…
A Graph is a data structure that consists of a set of nodes interconnected by directed or un-directed arcs. For a DIRECTED Graph, the ordered pair of nodes are written within angled brackets while for a UN-DIRECTED Graph, they are written within parenthesis. Consider a directed graph as depicted below – Below are the main point to note about the above…
Merge Sort Merge Sort is a process of combining more than one sorted files into a single sorted file. The procedure is to divide a file of size n into n sub files of size 1 each. Now combine each adjacent sub files to form a set of n/2 sub files. Sort each sub files….
Insertion Sort is a simple implementation of the general straight selection sort. A simple routine for insertion sort can be written as below – void insertionsort(int x[], int n){ int i, k, y; /*It is assumed that X[0] is already sorted*/ for(k = 1; k < n; k++){ y = x[k]; for(i = k-1; i> =0…
Heap is an almost complete Binary Tree implemented in a sequential format such that the value at any of the nodes (nd) is >= or <= value of the children. If nd >= children –> Maxheap ; If nd <= children –> Minheap ; Inserting an item to a Heap Join the item at the end of…
Binary Tree Sort uses a Binary search tree. The various steps involved in such a sort would be – Construct a binary tree with the given data (integers) such that all numbers to the left of a particular node say ‘nd’ is less than the number contained within the node and to the right, the numbers…
A Selection sorting technique uses a general algorithm which uses an ascending or descending priority queue. The idea would be to pre-process input array X[i] into the descending or ascending priority queues by the functions dpqinsert(dpq, x) or apqinsert(apq, x) respectively. Now, the next and final step would be to select data in appropriate order from…
The popular exchange sort mechanisms are Mean sort, Quick Sort and BSort and Quick sort is the most simple one. Quick sort is most applicable exchange sorting technique for practical applications since it uses relatively less time-space resources. Lets illustrate finding Order of a Quick sort algorithm in C. Lets start with the below list…
Lets explain Bubble sort by illustrating tow specific examples involving steps where smaller numbers bubbles to first and when larger numbers bubbles to last. Number list to sort: 2  5  3  0  6  1 Case 1: Smaller numbers bubbles to first Step 1:  0 5 3 2 6 1 Step 2:  0 3 5 2 …
Efficiency Considerations The following are the efficiency considerations while planning for a sorting program / algorithm – Time required to code the program and the type of sorting technique to be selected Execution time Amount of space required by program In cases where the type of data to be sorted is known, it is easier…
Towers of Hanoi problem consists of 3 pegs A, B and C. Let n denote number of disks in peg A. The objective is to transfer these disks from A to C using B as auxiliary so that at a time only one disk is transferred and a larger one cannot reside on a smaller…
In general cases, a non-recursive program runs more efficiently than a recursive program since a recursive program requires more execution time to enter and exit from a function. Recursive programs flows directly from the definitions and are easy to implement while a corresponding non-recursive program may involve expensive use of stacks which are difficult to…
Recursion Recursion and Iteration are two different concepts of achieving a result by a number of repeated operations. Iteration involves use of for, while and do-while loops for the repeated operation until specified condition. Recursion involves a recursive function calling itself several times until specified condition. A recursive function represents the most simpler form of…
Doubly Linked lists eliminates below drawbacks of circular lists – not able to traverse backward not able to delete and node given only points to that node. In a doubly linked list, every node has three fields – left, right and info. Each node has two pointers left and right which points to the left…
Josephus Problem Josephus problem is that some soldiers are being surrounded by their enemies and there is only one horse to escape i.e. only one soldier could escape and summon help. The remedy is to arrange soldiers’ names as a circular list. Now, any number say ‘n’ is inputed (selected) where n < number of…
Circular lists eliminates same drawbacks of linear lists. In as circular list it is assumed that items are inserted at the front and the list pointer points to the currently inserted node. Now, in this currently inserted circular list items, node or item is the last node of the list (and is this the rear…
Below are the advantages of Dynamic representation of Lists over its Array implementation –  No advanced knowledge of number of nodes is required  No memory space is wasted by bulk allocation as in the case of a large array since memory space is allocated only when a node is created  A reference to a pointer…
When Dynamic Linked Lists are represented as Queues, the first node represents front of queue given by q.front and last node represents the rear of the queue given by q.rear where q.front and q.rear are pointers. Thus Qinsert(q,x) and Qdelete(q) could be implemented as below – Qinsert(q,x){ p = getnode(); info(p) = x; next(p) =…