regex101: FORMAT DATE WITH NO SEPARATOR

Explanation

Pro

^start of line

Group 1((([D]{1,4}|[M]{1,4}|[Y]{2}|[Y]{4})([D]{1,4}|[M]{1,4}|[Y]{2}|[Y]{4}))([D]{1,4}|[M]{1,4}|[Y]{2}|[Y]{4}))

Group 2(([D]{1,4}|[M]{1,4}|[Y]{2}|[Y]{4})([D]{1,4}|[M]{1,4}|[Y]{2}|[Y]{4}))

Group 3([D]{1,4}|[M]{1,4}|[Y]{2}|[Y]{4})

1st Alternative[D]{1,4}

Character Class[D]{1,4}

{1,4}matches between 1 and 4 characters from the set below:

Dthe literal D (68₁₀ / 104₈ / 44₁₆) (case sensitive)

2nd Alternative[M]{1,4}

Character Class[M]{1,4}

{1,4}matches between 1 and 4 characters from the set below:

Mthe literal M (77₁₀ / 115₈ / 4D₁₆) (case sensitive)

3rd Alternative[Y]{2}

Character Class[Y]{2}

{2}matches exactly 2 characters from the set below:

Ythe literal Y (89₁₀ / 131₈ / 59₁₆) (case sensitive)

4th Alternative[Y]{4}

Character Class[Y]{4}

{4}matches exactly 4 characters from the set below:

Ythe literal Y (89₁₀ / 131₈ / 59₁₆) (case sensitive)

Group 4([D]{1,4}|[M]{1,4}|[Y]{2}|[Y]{4})

1st Alternative[D]{1,4}

Character Class[D]{1,4}

{1,4}matches between 1 and 4 characters from the set below:

Dthe literal D (68₁₀ / 104₈ / 44₁₆) (case sensitive)

2nd Alternative[M]{1,4}

Character Class[M]{1,4}

{1,4}matches between 1 and 4 characters from the set below:

Mthe literal M (77₁₀ / 115₈ / 4D₁₆) (case sensitive)

3rd Alternative[Y]{2}

Character Class[Y]{2}

{2}matches exactly 2 characters from the set below:

Ythe literal Y (89₁₀ / 131₈ / 59₁₆) (case sensitive)

4th Alternative[Y]{4}

Character Class[Y]{4}

{4}matches exactly 4 characters from the set below:

Ythe literal Y (89₁₀ / 131₈ / 59₁₆) (case sensitive)

Group 5([D]{1,4}|[M]{1,4}|[Y]{2}|[Y]{4})

1st Alternative[D]{1,4}

Character Class[D]{1,4}

{1,4}matches between 1 and 4 characters from the set below:

Dthe literal D (68₁₀ / 104₈ / 44₁₆) (case sensitive)

2nd Alternative[M]{1,4}

Character Class[M]{1,4}

{1,4}matches between 1 and 4 characters from the set below:

Mthe literal M (77₁₀ / 115₈ / 4D₁₆) (case sensitive)

3rd Alternative[Y]{2}

4th Alternative[Y]{4}

$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

Quick Reference

25 tokens

Regular Expression

^((([D]{1,4}|[M]{1,4}|[Y]{2}|[Y]{4})([D]{1,4}|[M]{1,4}|[Y]{2}|[Y]{4}))([D]{1,4}|[M]{1,4}|[Y]{2}|[Y]{4}))$

MMMMDDYY
MDYY
YYYYDDMM
MDYY
DDDDDYYYMM
OODDYYMM
YYDDMMPPPP