Regular Expressions 101

Negative Lookbehind(?<![a-zA-Z])

Character Class[a-zA-Z]

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

Character Class[0-9]

0-9one character from 0 (48₁₀) to 9 (57₁₀)

Character Class[\.0-9]*

*matches any number of characters from the set below:

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

0-9one character from 0 (48₁₀) to 9 (57₁₀)

Negative Lookahead(?![a-zA-Z])

Character Class[a-zA-Z]

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

Global pattern flags

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

Detailed match information will be displayed here automatically.

25 tokens

Regular Expression

(?<![a-zA-Z])[0-9][\.0-9]*(?![a-zA-Z])

New

Theses are some of the fail cases that I am looking to 
avoid variable123 or variable_123name or _123_,
where some of the acceptable cases are |123| or +123+ $123 123% #124523 ext... 11 2123  123% 0.12 1.1.3.4.4 12 1 23452 23423| ext...[