MATLAB Function Reference

regexprep

Replace string using regular expression

Syntax

• s = regexprep(str,expr,replace)
  

s = regexprep(str,expr,replace,options)

Description

s = regexprep(str,expr,replace) replaces all occurrences of the regular expression, expr, in string, str, with the string, replace. The new string is returned. If no matches are found regexprep returns str unchanged.

When any of str, expr, or replace are cell arrays of strings, regexprep returns an m-by-n-by-p cell array of strings, where m is the number of strings in str, n is the number of regular expressions in expr, and p is the number of strings in replace.

s = regexprep(str,expr,replace,options) By default, regexprep replaces all matches, is case sensitive, and does not use tokens. You can use one or more of the following options with regexprep.

Option	Description
ignorecase	Ignore the case of characters when matching expr to str.
preservecase	Ignore case when matching (as with 'ignorecase'), but override the case of replace characters with the case of corresponding characters in str when replacing.
tokenize	Modify replace to use the tokens delimited by parenthesis in expr such that $1 is the first token, $2 is the second token, ..., and $N is the Nth token.
once	Replace only the first occurrence of expr in str.
N	Replace only the Nth occurrence of expr in str.

Remarks

See Regular Expressions, in the MATLAB documentation, for a listing of all regular expression metacharacters supported by MATLAB.

regexprep does not support international character sets.

Examples

Example 1

Perform a case-sensitive replacement on words starting with m and ending with y:

• str = 'My flowers may bloom in May';
  pat = 'm(\w*)y';
  regexprep(str, pat, 'April')
  ans =
     My flowers April bloom in May
  

Replace all words starting with m and ending with y, regardless of case, but maintain the original case in the replacement strings:

• regexprep(str, pat, 'April', 'preservecase')
  ans =
     April flowers april bloom in April
  

Example 2

Replace all variations of the words 'walk up' using the letters following walk as a token.

• str = 'I walk up, they walked up, we are walking up, she walks.';
  pat = 'walk(\w*) up';
  regexprep(str, pat, 'ascend$1', 'tokenize')
  ans =
     I ascend, they ascended, we are ascending, she walks.
  

See Also

regexp, regexpi, strfind, findstr, strmatch, strcmp, strcmpi, strncmp, strncmpi

regexpi

registerevent (COM)