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25 lines
1.1 KiB
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25 lines
1.1 KiB
Markdown
# Pycalc
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**Pycalc** is a simple expression calculator. It can evaluate mathematical expressions, and output the result of the evaluation.
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## How it works
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1. Scan the expression
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- Check for malformed expression and invalid characters
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- Tokenize the expression (I wrote a custom parser to do this)
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2. If there are any parantheses, replace the parantheses with the result of the sub-expression.
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3. Evaluate the overall expression (which should no longer have any parantheses)
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Rather than building a tree from the expression (which is the recommended approach), I have opted to perform the substitutions in-place. This means that the result of an operation replaces the operation itself.
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The reason I chose to do this, is that my parsing algorithm considers everything inside parantheses as a single token. Therefore, it is fairly easy to replace this token with the result of the expression within the parantheses.
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## Features
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- Order of operations
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- Arbitrary whitespace
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- Parantheses
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- Simple error checking
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## To-do
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- ~~Simple algebraic parsing (assign values to variables, etc.)~~
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- More robust error-checking
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