Regular Expressions 101

Explanation

Pro

^start of line

Positive Lookahead(?=[^@]*@[^@]*$)

Negated Character Class[^@]*

*matches any number of characters outside the set below:

@the literal @ (64₁₀ / 100₈ / 40₁₆)

Negated Character Class[^@]*

*matches any number of characters outside the set below:

@the literal @ (64₁₀ / 100₈ / 40₁₆)

$end of line

Character Class[A-Za-z@]*

*matches any number of characters from the set below:

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

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

@the literal @ (64₁₀ / 100₈ / 40₁₆)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Character Class[A-Za-z@.]*

*matches any number of characters from the set below:

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

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

@the literal @ (64₁₀ / 100₈ / 40₁₆)

.the literal . (46₁₀ / 56₈ / 2E₁₆)

$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

Detailed match information will be displayed here automatically.

25 tokens

^(?=[^@]*@[^@]*$)[A-Za-z@]*\.[A-Za-z@.]*$

New

abcd@.
@ab.cd
a@cd@.
abcd@
@ab.cd.

abcd@.
@ab.cd
a@cd@.
abcd@
@ab.cd.