Construction of a UK Postcode Regular Expression

gistfile1.mkd

First Half

Character sets for positions

1. [A-PR-UWYZ]
2. [A-HK-Y]
3. [A-HJKS-UW]
4. [ABEHMNPRV-Y]

Formats

1. AN [A-PR-UWYZ][0-9]
2. ANN [A-PR-UWYZ][0-9]{2}
3. AAN [A-PR-UWYZ][A-HK-Y][0-9]
4. AANN [A-PR-UWYZ][A-HK-Y][0-9]{2}
5. ANA [A-PR-UWYZ][0-9][A-HJKS-UW]
6. AANA [A-PR-UWYZ][A-HK-Y][0-9][ABEHMNPRV-Y]

Reordered Formats

1. AN [A-PR-UWYZ][0-9]
2. ANN [A-PR-UWYZ][0-9][0-9]
3. ANA [A-PR-UWYZ][0-9][A-HJKS-UW]
4. AAN [A-PR-UWYZ][A-HK-Y][0-9]
5. AANN [A-PR-UWYZ][A-HK-Y][0-9][0-9]
6. AANA [A-PR-UWYZ][A-HK-Y][0-9][ABEHMNPRV-Y]

Combined Formats

1,2,3.

[A-PR-UWYZ][0-9]([0-9]|[A-HJKS-UW])?

4,5,6.

[A-PR-UWYZ][A-HK-Y][0-9]([0-9]|[ABEHMNPRV-Y])?

Combined

[A-PR-UWYZ]([0-9]([0-9]|[A-HJKS-UW])?|[A-HK-Y][0-9]([0-9]|[ABEHMNPRV-Y])?)

Second Half

1. [0-9]
2. [ABD-HJLNP-UW-Z]
3. [ABD-HJLNP-UW-Z]

Combined

\s[0-9][ABD-HJLNP-UW-Z]{2}

First and Second Combined

[A-PR-UWYZ]([0-9]([0-9]|[A-HJKS-UW])?|[A-HK-Y][0-9]([0-9]|[ABEHMNPRV-Y])?)\s[0-9][ABD-HJLNP-UW-Z]{2}

Historical Exceptions

1. GIR 0AA

Full Combined

(GIR 0AA|[A-PR-UWYZ](?:[0-9](?:[0-9]|[A-HJKS-UW])?|[A-HK-Y][0-9](?:[0-9]|[ABEHMNPRV-Y])?)\s[0-9][ABD-HJLNP-UW-Z]{2})