Regular Expressions 101

Pro

Negative Lookahead(?!.+T.+)

.+any character (except for line terminators), repeated at least once

Tthe literal T (84₁₀ / 124₈ / 54₁₆) (case sensitive)

.+any character (except for line terminators), repeated at least once

Group 1(M)

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

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

Detailed match information will be displayed here automatically.

25 tokens

(?!.+T.+)(M)

New

P3Y6M4DT12H30M5S
PT12H30M5S
PT12H30M5.234523S

REPLACEMENT

P3Y6M4DT12H30M5S
PT12H30M5S
PT12H30M5.234523S