regex101: Date checker for X values

^start of line

Group 1((?! xxxx-xx-xx)((19|20|x)[0-9x][0-9x])\-((02\-(-[1-9]|[1-2]\d|xx))|((04|06|09|11)\-(0[1-9]|[1-2]\d|30|xx))|((01|03|05|07|08|10|12|xx)\-(0[1-9]|[1-2]\d|30|31|xx)))((?! xx:xx:xx) ([0-1]\d|2[0-3]|xx):([0-5]\d|xx)(:([0-5]\d|xx)|))?)

Negative Lookahead(?! xxxx-xx-xx)

xxxx-xx-xxthe literal text xxxx-xx-xx (case sensitive)

Group 2((19|20|x)[0-9x][0-9x])

Group 3(19|20|x)

1st Alternative19

19the literal text 19

2nd Alternative20

20the literal text 20

3rd Alternativex

xthe literal x (120₁₀ / 170₈ / 78₁₆) (case sensitive)

Character Class[0-9x]

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

xthe literal x (120₁₀ / 170₈ / 78₁₆) (case sensitive)

Character Class[0-9x]

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

xthe literal x (120₁₀ / 170₈ / 78₁₆) (case sensitive)

\-the literal - (45₁₀ / 55₈ / 2D₁₆)

Group 4((02\-(-[1-9]|[1-2]\d|xx))|((04|06|09|11)\-(0[1-9]|[1-2]\d|30|xx))|((01|03|05|07|08|10|12|xx)\-(0[1-9]|[1-2]\d|30|31|xx)))

1st Alternative(02\-(-[1-9]|[1-2]\d|xx))

Group 5(02\-(-[1-9]|[1-2]\d|xx))

02the literal text 02

\-the literal - (45₁₀ / 55₈ / 2D₁₆)

Group 6(-[1-9]|[1-2]\d|xx)

1st Alternative-[1-9]

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Character Class[1-9]

1-9one character from 1 (49₁₀) to 9 (57₁₀)

2nd Alternative[1-2]\d

Character Class[1-2]

1-2one character from 1 (49₁₀) to 2 (50₁₀)

\da digit

3rd Alternativexx

xxthe literal text xx (case sensitive)

2nd Alternative((04|06|09|11)\-(0[1-9]|[1-2]\d|30|xx))

Group 7((04|06|09|11)\-(0[1-9]|[1-2]\d|30|xx))

Group 8(04|06|09|11)

1st Alternative04

04the literal text 04

2nd Alternative06

06the literal text 06

3rd Alternative09

09the literal text 09

4th Alternative11

11the literal text 11

\-the literal - (45₁₀ / 55₈ / 2D₁₆)

Group 9(0[1-9]|[1-2]\d|30|xx)

3rd Alternative((01|03|05|07|08|10|12|xx)\-(0[1-9]|[1-2]\d|30|31|xx))

Group 13((?! xx:xx:xx) ([0-1]\d|2[0-3]|xx):([0-5]\d|xx)(:([0-5]\d|xx)|))?

$end of line

Global pattern flags

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

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

Search reference

Regular Expression

^((?! xxxx-xx-xx)((19|20|x)[0-9x][0-9x])\-((02\-(-[1-9]|[1-2]\d|xx))|((04|06|09|11)\-(0[1-9]|[1-2]\d|30|xx))|((01|03|05|07|08|10|12|xx)\-(0[1-9]|[1-2]\d|30|31|xx)))((?! xx:xx:xx) ([0-1]\d|2[0-3]|xx):([0-5]\d|xx)(:([0-5]\d|xx)|))?)$

Unit Tests

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