regex101: calculator expressions

^start of line

Group 1([A-z]+)

Character Class[A-z]+

+matches at least one character from the set below:

A-zone character from A (65₁₀) to z (122₁₀) (case sensitive)

Non-Capturing Group(?: *= *)

*the literal (32₁₀ / 40₈ / 20₁₆) , repeated any number of times

=the literal = (61₁₀ / 75₈ / 3D₁₆)

*the literal (32₁₀ / 40₈ / 20₁₆) , repeated any number of times

Group 2(\d+|[A-z]+)

1st Alternative\d+

\d+a digit, repeated at least once

2nd Alternative[A-z]+

Character Class[A-z]+

+matches at least one character from the set below:

A-zone character from A (65₁₀) to z (122₁₀) (case sensitive)

$end of line

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Search reference

Regular Expression

^([A-z]+)(?: *= *)(\d+|[A-z]+)$

New

Expression validator
^((?:[A-z]+)|((-|\+)?\d+))( +(\++|-+) +((?:-?\d+)|(?:[A-z]+)))*$

Assignment validator
^([A-z]+)(?: *= *)(\d+|[A-z]+)$

c=  a
8
8 + 4
-2 + 4 - 5 + 6

9 +++  - 10 -- 8
9 --- + 10
9 --- -10
9 +++  -10 -- 8
3 --- 5
14  -   12
-3 2
name = 44
a = 5
capName = 6 + 4
capName = 6
n = 3
m=4
a  =   5
b = a
v=   7
n =9
c= a
A variable can have a name consisting of more than one letter.

count = 10
To print the value of a variable you should just type its name.

N = 5
N
5
It should be possible to set a new value to an existing variable.

a = 1
a = 2
a = 3
a
3
If an identifier or value of a variable is invalid, the program must print a message like the one below.

a1 = 8
Invalid identifier
n = a2a
Invalid assignment
a = 7 = 8
Invalid assignment

Regular Expressions 101

Regular Expression

Substitution