Regular Expressions 101

^start of line

Negative Lookahead(?![^'\-_\n]*['\-_][^'\-_\n]*['\-_])

Negated Character Class[^'\-_\n]*

*matches any number of characters outside the set below:

'the literal ' (39₁₀ / 47₈ / 27₁₆)

\-the literal - (45₁₀ / 55₈ / 2D₁₆)

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

\na line-feed (newline) character (ASCII 10)

Character Class['\-_]

'the literal ' (39₁₀ / 47₈ / 27₁₆)

\-the literal - (45₁₀ / 55₈ / 2D₁₆)

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

Negated Character Class[^'\-_\n]*

*matches any number of characters outside the set below:

'the literal ' (39₁₀ / 47₈ / 27₁₆)

\-the literal - (45₁₀ / 55₈ / 2D₁₆)

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

\na line-feed (newline) character (ASCII 10)

Character Class['\-_]

'the literal ' (39₁₀ / 47₈ / 27₁₆)

\-the literal - (45₁₀ / 55₈ / 2D₁₆)

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

Character Class[a-z .',-_]+

+matches at least one character from the set below:

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

the literal (32₁₀ / 40₈ / 20₁₆)

.the literal . (46₁₀ / 56₈ / 2E₁₆)

'the literal ' (39₁₀ / 47₈ / 27₁₆)

,-_one character from , (44₁₀) to _ (95₁₀)

$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

i modifier: insensitive. Matches without distinguishing uppercase and lowercase letters

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

^(?![^'\-_\n]*['\-_][^'\-_\n]*['\-_])[a-z .',-_]+$

New

It should be valid if a Surname is:
abcd
abcd'efg
abcd-efg
abcd, .efg
etc...

I also need to test if symbols do not repeat... so for example:

abcd''efg
abcd-',

Are invalid but the one:

abcd, .efg

Can be valid.

At the moment I just created this:

^[a-z .',-_]+$
And now I'm trying to check for all the double symbols but I cannot go ahead successfully.

Mc'Millan, .jr