regex101: PCRE (Legacy) Substitution Workspace

^start of line

Group 1(((\r?\n|\s)*[A-Za-z0-9+\/]){4})*

*repeats the group contents below any number of times:

Group 2((\r?\n|\s)*[A-Za-z0-9+\/]){4}

{4}repeats the group contents below exactly 4 times:

Group 3(\r?\n|\s)*

*repeats the group contents below any number of times:

1st Alternative\r?\n

\r?optionally matches a carriage return (ASCII 13)

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

2nd Alternative\s

\sany whitespace character

Character Class[A-Za-z0-9+\/]

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

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

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

+the literal + (43₁₀ / 53₈ / 2B₁₆)

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

Group 4(((\r?\n|\s)*[A-Za-z0-9+\/]){2}(=(\r?\n|\s)*){2}|((\r?\n|\s)*[A-Za-z0-9+\/]){3}(=(\r?\n|\s)*))?

?repeats the group contents below at most once:

1st Alternative((\r?\n|\s)*[A-Za-z0-9+\/]){2}(=(\r?\n|\s)*){2}

Group 5((\r?\n|\s)*[A-Za-z0-9+\/]){2}

{2}repeats the group contents below exactly 2 times:

Group 6(\r?\n|\s)*

*repeats the group contents below any number of times:

1st Alternative\r?\n

\r?optionally matches a carriage return (ASCII 13)

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

2nd Alternative\s

\sany whitespace character

Character Class[A-Za-z0-9+\/]

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

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

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

+the literal + (43₁₀ / 53₈ / 2B₁₆)

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

Group 7(=(\r?\n|\s)*){2}

{2}repeats the group contents below exactly 2 times:

=the literal = (61₁₀ / 75₈ / 3D₁₆)

Group 8(\r?\n|\s)*

*repeats the group contents below any number of times:

1st Alternative\r?\n

\r?optionally matches a carriage return (ASCII 13)

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

2nd Alternative\s

\sany whitespace character

2nd Alternative((\r?\n|\s)*[A-Za-z0-9+\/]){3}(=(\r?\n|\s)*)

Group 9((\r?\n|\s)*[A-Za-z0-9+\/]){3}

{3}repeats the group contents below exactly 3 times:

Group 10(\r?\n|\s)*

*repeats the group contents below any number of times:

1st Alternative\r?\n

\r?optionally matches a carriage return (ASCII 13)

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

2nd Alternative\s

\sany whitespace character

Character Class[A-Za-z0-9+\/]

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

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

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

+the literal + (43₁₀ / 53₈ / 2B₁₆)

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

Group 11(=(\r?\n|\s)*)

=the literal = (61₁₀ / 75₈ / 3D₁₆)

Group 12(\r?\n|\s)*

*repeats the group contents below any number of times:

1st Alternative\r?\n

2nd Alternative\s

$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

^(((\r?\n|\s)*[A-Za-z0-9+\/]){4})*(((\r?\n|\s)*[A-Za-z0-9+\/]){2}(=(\r?\n|\s)*){2}|((\r?\n|\s)*[A-Za-z0-9+\/]){3}(=(\r?\n|\s)*))?$

Unit Tests

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