C: nucleotide-count & rna-transcription

c/nucleotide-count/README.md

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+# Nucleotide Count
+
+Each of us inherits from our biological parents a set of chemical instructions known as DNA that influence how our bodies are constructed. All known life depends on DNA!
+
+> Note: You do not need to understand anything about nucleotides or DNA to complete this exercise.
+
+DNA is a long chain of other chemicals and the most important are the four nucleotides, adenine, cytosine, guanine and thymine. A single DNA chain can contain billions of these four nucleotides and the order in which they occur is important!
+We call the order of these nucleotides in a bit of DNA a "DNA sequence".
+
+We represent a DNA sequence as an ordered collection of these four nucleotides and a common way to do that is with a string of characters such as "ATTACG" for a DNA sequence of 6 nucleotides.
+'A' for adenine, 'C' for cytosine, 'G' for guanine, and 'T' for thymine.
+
+Given a string representing a DNA sequence, count how many of each nucleotide is present.
+If the string contains characters that aren't A, C, G, or T then it is invalid and you should signal an error.
+
+For example:
+
+```
+"GATTACA" -> 'A': 3, 'C': 1, 'G': 1, 'T': 2
+"INVALID" -> error
+```
+
+## Getting Started
+
+Make sure you have read the "Guides" section of the
+[C track][c-track] on the Exercism site. This covers
+the basic information on setting up the development environment expected
+by the exercises.
+
+## Passing the Tests
+
+Get the first test compiling, linking and passing by following the [three
+rules of test-driven development][3-tdd-rules].
+
+The included makefile can be used to create and run the tests using the `test`
+task.
+
+    make test
+
+Create just the functions you need to satisfy any compiler errors and get the
+test to fail. Then write just enough code to get the test to pass. Once you've
+done that, move onto the next test.
+
+As you progress through the tests, take the time to refactor your
+implementation for readability and expressiveness and then go on to the next
+test.
+
+Try to use standard C99 facilities in preference to writing your own
+low-level algorithms or facilities by hand.
+
+## Source
+
+The Calculating DNA Nucleotides_problem at Rosalind [http://rosalind.info/problems/dna/](http://rosalind.info/problems/dna/)
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.
+
+[c-track]: https://exercism.io/my/tracks/c
+[3-tdd-rules]: http://butunclebob.com/ArticleS.UncleBob.TheThreeRulesOfTdd