Rust Arithmetic Expression Evaluator

This is a simple program that takes as input an arithmetic expression and outputs its evaluation

How to use

You must provide an arithmetic expression to the program.

Operators

Here are the operations handled:

• PLUS (+)
• MINUS (-)
• MULTIPLY (x) or (*) in standard input
• DIVIDE (/)
• POWER (^)

All numbers and operators must be separated by a space, except for unary operators, in which case they must be attached to the number.

Here are the unary operators handled:

• MINUS (-)

You can only use one unary operator for one number (e.g --2 is invalid input)

Variables

You can also define variables, and use them in the computation. For that, you need to start the program without any arguments. Here is the syntax to define a variable:

variable=expression

where variable is the name of the variable and expression an arithmetic expression. You can only define one variable by line. When defining new variables, you can use the previous ones that defined before

Examples

$ means that this is a terminal command

> means that this is the standard input

the output is the last line

$ ./main 1 + 3 x 2
7

$ ./main 1 + 3 x -2
-5

$ ./main
> a=3 + 2
> b= a + 1
> a + b
11

$ ./main
> a = 3 + 2
> b=a * 2
> a + b
15

$ ./main < computation.txt
15

where computation.txt is a file whose content is last example's standard input