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Testing is the process of executing a program with the intent of finding errors.We should test the program´s responses to every possible input. It means, we should test for all valid and invalid inputs. Suppose a program requires two 8 bit integers as inputs. Total possible combinations are 28x28. If only one second it required to execute one set of inputs, it may take 18 hours to test all combinations. Practically, inputs are more than two and size is also more than 8 bits. We have also not considered invalid inputs where so many combinations are possible. Hence, complete testing is just not possible, although, we may wish to do so.

There are three phases in the life of any hardware component i.e., burn-in, useful life & wear-out. In burn-in phase, failure rate is quite high initially, and it starts decreasing gradually as the time progresses. During useful life period, failure rate is approximately constant. Failure rate increase in wear-out phase due to wearing out/aging of components. The best period is useful life period. The shape of this curve is like a "bath tub" and that is why it is known as bath tub curve.

Software metrics can be defined as "The continuous application of measurement based techniques to the software development process and its products to supply meaningful and timely management information, together with the use of those techniques to improve that process and its products". The most established area of software metrics is cost and size estimation techniques. The prediction of quality levels for software, often in terms of reliability, is another area where software metrics have an important role to play. The use of software metrics to provide quantitative checks on software design is also a well established area.

Modularity is the single attribute of software that allows a program to be intellectually manageable. It enhances design clarity, which in turn eases implementation, debugging, testing, documenting, and maintenance of software product.

After the finalisation of SRS, we would like to estimate size, cost and development time of the project. Also, in many cases, customer may like to know the cost and development time even prior to finalisation of the SRS. Software planning begins before technical work starts, continues as the software evolves from concept to reality, and culminates only when the software is retired.

Requirements describe What not How: Produces one large document written in natural language contains a description of what the system will do without describing how it will do it. Requirement Engineering is the disciplined application of proven principles, methods, tools, and notations to describe a proposed system?s intended behavior and its associated constraints.

The goal of Software Engineering is to provide models and processes that lead to the production of well documented maintainable software in a manner that is predictable. The period of time that starts when a software product is conceived and ends when the product is no longer available for use. The software life cycle typically includes a requirement phase, design phase, implementation phase, test phase, installation and check out phase, operation and maintenance phase, and sometimes retirement phase.

As per the IBM report, "31%of the project get cancelled before they are completed, 53% over-run their cost estimates by an average of 189% and for every 100 projects, there are 94 restarts".

This pdf file contains about 180 question based on C programming concepts. Each question has it's correct answer and explanation i.e. how it's correct. Which version do you prefer of the following two, 1) printf(?%s?,str); // or the more curt one 2) printf(str); Answer & Explanation: Prefer the first one. If the str contains any format characters like %d then it will result in a subtle bug.

Top-level issues: 1. Safety, security and privacy 2. Security policy 2.1 threats, both external and internal 2.2 economic gains 2.3 cost of securing resources 2.4 cryptographic methods vs. physical security 3. Information security: 3.1 nature of resources (HW, SW, information) 3.2 during storage, access and communication 3.3 limited to a single computer vs. network security 3.4 various layers (physical through application layers)