#### Overview of this book

The number of popular technical practices has grown exponentially in the last few years. Learning the common fundamental software development practices can help you become a better programmer. This book uses the term Agile as a wide umbrella and covers Agile principles and practices, as well as most methodologies associated with it. You’ll begin by discovering how driver-navigator, chess clock, and other techniques used in the pair programming approach introduce discipline while writing code. You’ll then learn to safely change the design of your code using refactoring. While learning these techniques, you’ll also explore various best practices to write efficient tests. The concluding chapters of the book delve deep into the SOLID principles - the five design principles that you can use to make your software more understandable, flexible and maintainable. By the end of the book, you will have discovered new ideas for improving your software design skills, the relationship within your team, and the way your business works.
Preface
Free Chapter
Section 1
Chapter 1
Chapter 2
Chapter 4
Chapter 5
Section 2
Chapter 6
Chapter 7
Chapter 8
Chapter 9
Chapter 10
Section 3
Chapter 11
Chapter 13
Chapter 14
Chapter 15
Section 4
Chapter 16
Chapter 17
Chapter 19
Chapter 20
Chapter 21
Chapter 22
Chapter 23
Sample Solutions
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# Connascence of Algorithm

Connascence of Algorithm (CoA) occurs when two or more components must agree on using a particular algorithm.

Perhaps the most popular example of this kind of connascence is `checksum` for file verification; applying the algorithm remotely allows for a mathematical proof that the file has not been changed.

Unfortunately, if we have this kind of connascence in our code, the result is not useful. Let's see an example of a dumb `checksum` implementation that assumes we want to build it with a simple logic consisting of adding a character at the end of an integer so that the sum of the single numbers could be divided by 10:

```AddChecksum("32143")    =>   "321437"
Check("321437")         =>   true
Check("321432")         =>   false```

Let's see this snippet implementing it:

```public string AddChecksum(string inputData){
var sum = SumCharsOf(inputData);
...```