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Match boundary before specified pattern



newpat = lookBehindBoundary(pat) creates a pattern that matches the end of pat. Text matched by pat is not included in the result. lookBehindBoundary can be negated using the ~ operator. When negated, ~lookBehindBoundary matches between any characters that are not at the end of pat.


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Create a pattern that matches behind "b" or "2".

txt = "abc 123";
pat = lookBehindBoundary("b"|"2");

Use replace to insert "|" characters at the matched boundaries.

ans = 
"ab|c 12|3"

Use the ~ operator to negate lookBehindBoundary.

Create a pattern that matches digits except for those that directly follow "b" or "2".

txt = "abc 123";
pat = ~lookBehindBoundary("b"|"2");

Use replace to insert "|" characters at the negated boundaries.

ans = 
"|a|bc| |1|23|"

Input Arguments

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Input pattern, specified as a pattern, string array, character vector, or cell array of character vectors.

Data Types: char | string | pattern | cell

Output Arguments

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Output pattern, returned as a pattern or an array of pattern objects.

Introduced in R2020b