56 lines
2.3 KiB
Markdown
56 lines
2.3 KiB
Markdown
# Trinary
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Write a program that will convert a trinary number, represented as a string (e.g. '102012'), to its decimal equivalent using first principles.
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The program should consider strings specifying an invalid trinary as the
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value 0.
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Trinary numbers contain three symbols: 0, 1, and 2.
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The last place in a trinary number is the 1's place. The second to last
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is the 3's place, the third to last is the 9's place, etc.
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```bash
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# "102012"
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1 0 2 0 1 2 # the number
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1*3^5 + 0*3^4 + 2*3^3 + 0*3^2 + 1*3^1 + 2*3^0 # the value
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243 + 0 + 54 + 0 + 3 + 2 = 302
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```
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If your language provides a method in the standard library to perform the
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conversion, pretend it doesn't exist and implement it yourself.
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## Getting Started
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Make sure you have read [the C++ page](http://exercism.io/languages/cpp) on
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exercism.io. This covers the basic information on setting up the development
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environment expected by the exercises.
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## Passing the Tests
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Get the first test compiling, linking and passing by following the [three
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rules of test-driven development](http://butunclebob.com/ArticleS.UncleBob.TheThreeRulesOfTdd).
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Create just enough structure by declaring namespaces, functions, classes,
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etc., to satisfy any compiler errors and get the test to fail. Then write
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just enough code to get the test to pass. Once you've done that,
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uncomment the next test by moving the following line past the next test.
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```C++
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#if defined(EXERCISM_RUN_ALL_TESTS)
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```
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This may result in compile errors as new constructs may be invoked that
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you haven't yet declared or defined. Again, fix the compile errors minimally
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to get a failing test, then change the code minimally to pass the test,
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refactor your implementation for readability and expressiveness and then
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go on to the next test.
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Try to use standard C++11 facilities in preference to writing your own
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low-level algorithms or facilities by hand. [CppReference](http://en.cppreference.com/)
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is a wiki reference to the C++ language and standard library. If you
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are new to C++, but have programmed in C, beware of
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[C traps and pitfalls](http://www.slideshare.net/LegalizeAdulthood/c-traps-and-pitfalls-for-c-programmers).
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## Source
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All of Computer Science [view source](http://www.wolframalpha.com/input/?i=binary&a=*C.binary-_*MathWorld-)
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