simple-calc is a command line calculator that consumes input expressions and outputs their evaluated results. It served as a nice sandbox project for:
- Setting up a command line interface
- Parsing and validating arbitrary input
- Learning more about parsing terminology, like postfix notation, and algorithms, like the shunting-yard algorithm
- Getting comfortable with error handling using
Results instead of exceptions
It can be used for scripting or as an interactive tool. Below is an example of the tool in action.
$ simple-calc "128 - (8 * 16 / ((3 + 1) / 2))"
64
$ simple-calc "7 + 2 ~ 3"
Error: "encountered invalid character ~ in expression at position 6"
$ simple-calc "4 * 9 + ("
Error: "input expression contains mismatched parentheses"
$ simple-calc
Using simple-calc in interactive mode.
Use '$?' to access the previous result.
Use '${N}' to go further back in history.
Enter 'exit' to quit.
>> 0 + 1
The result is 1.
>> $? + 1
The result is 2.
>> $0 + $1
The result is 3.
>> exit
Thanks for using simple-calc. Peace.The following commands are used most frequently during development:
cargo build # build (development)
cargo test # execute tests
cargo run # run (will build as well)
cargo install # install to local machine