# Binary in Elixir

#### Convert a binary number, represented as a string (e.g. '101010'), to its decimal equivalent using first principles

1 | ```
exercism fetch elixir binary
``` |

# Binary

Convert a binary number, represented as a string (e.g. '101010'), to its decimal equivalent using first principles.

Implement binary to decimal conversion. Given a binary input string, your program should produce a decimal output. The program should handle invalid inputs.

## Note

- Implement the conversion yourself. Do not use something else to perform the conversion for you.

## About Binary (Base-2)

Decimal is a base-10 system.

A number 23 in base 10 notation can be understood as a linear combination of powers of 10:

- The rightmost digit gets multiplied by 10
^{0}= 1 - The next number gets multiplied by 10
^{1}= 10 - ...
- The
*n*th number gets multiplied by 10^*(n-1)*. - All these values are summed.

So: `23 => 2*10^1 + 3*10^0 => 2*10 + 3*1 = 23 base 10`

Binary is similar, but uses powers of 2 rather than powers of 10.

So: `101 => 1*2^2 + 0*2^1 + 1*2^0 => 1*4 + 0*2 + 1*1 => 4 + 1 => 5 base 10`

.

## Running tests

Execute the tests with:

1 |
```
$ elixir bob_test.exs
``` |

(Replace `bob_test.exs`

with the name of the test file.)

### Pending tests

In the test suites, all but the first test have been skipped.

Once you get a test passing, you can unskip the next one by
commenting out the relevant `@tag :pending`

with a `#`

symbol.

For example:

Or, you can enable all the tests by commenting out the
`ExUnit.configure`

line in the test suite.

1 |
```
# ExUnit.configure exclude: :pending, trace: true
``` |

For more detailed information about the Elixir track, please see the help page.

## Source

All of Computer Science http://www.wolframalpha.com/input/?i=binary&a=*C.binary-_*MathWorld-

## Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.