This is a simple Brainfuck (http://en.wikipedia.org/wiki/Brainfuck) interpreter written in C++.

The basics:
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Usage: [OPTION]... <source-file>

Options:
  -e, --evaluate=program    evaluate a one line program
  -i, --ignore-unknowns     ignore unknown commands within the program
  -s, --use-signed-cells    use a signed type for each cell
  -h, --help                print this message

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$ bf -e "++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>."
Hello World!
$