replace

Find and replace one or more substrings

Syntax

newStr = replace(str,old,new)

Description

newStr = replace(str,old,new) replaces all occurrences of the substring old with new. If old contains multiple substrings, then new either must be the same size as old, or must be a single substring.

Examples

Replace Substring in String Array

Replace placeholder text in a list of file names.

Starting in R2017a, you can create strings using double quotes.

str = ["<ROOT_DIR>\MyData\data.tar.gz";
       "<ROOT_DIR>\MyScripts\cleandata.m";
       "<ROOT_DIR>\MyScripts\preprocess.m";
       "<ROOT_DIR>\MyScripts\publishResults.m"]

str = 4x1 string
    "<ROOT_DIR>\MyData\data.tar.gz"
    "<ROOT_DIR>\MyScripts\cleandata.m"
    "<ROOT_DIR>\MyScripts\preprocess.m"
    "<ROOT_DIR>\MyScripts\publishResults.m"

If you are using R2016b, create string arrays using the string function instead of double quotes.

Replace <ROOT_DIR> with a string that is the name of a file path.

old = "<ROOT_DIR>";
new = "C:\MyProject";
newStr = replace(str,old,new)

newStr = 4x1 string
    "C:\MyProject\MyData\data.tar.gz"
    "C:\MyProject\MyScripts\cleandata.m"
    "C:\MyProject\MyScripts\preprocess.m"
    "C:\MyProject\MyScripts\publishResults.m"

Replace Substrings That Match Pattern

Since R2020b

Create a string that includes a phone number.

str = "Hide the numbers in: [phone]"

str = 
"Hide the numbers in: [phone]"

Create a pattern that matches a digit using the digitsPattern function.

pat = digitsPattern(1)

pat = pattern
  Matching:

    digitsPattern(1)

Replace all digits with a "#" character.

newStr = replace(str,pat,"#")

newStr = 
"Hide the numbers in: (###) ###-####"

Create another pattern that matches only phone numbers.

pat = "(" + digitsPattern(3) + ") " + digitsPattern(3)  + "-" + digitsPattern(4)

pat = pattern
  Matching:

    "(" + digitsPattern(3) + ") " + digitsPattern(3) + "-" + digitsPattern(4)

Replace a phone number in a string that also has another number.

str = "12 calls made to: [phone]";
newStr = replace(str,pat,"(###) ###-####")

newStr = 
"12 calls made to: (###) ###-####"

For a list of functions that create pattern objects, see pattern.

Replace Multiple Substrings

Replace carriage returns with newline characters.

Starting in R2017a, you can create strings using double quotes.

str = ["Submission Date: 11/29/15\r";
       "Acceptance Date: 1/20/16\r";
       "Contact: [e-mail]\r\n"]

str = 3x1 string
    "Submission Date: 11/29/15\r"
    "Acceptance Date: 1/20/16\r"
    "Contact: [e-mail]\r\n"

Replace the carriage returns.

old = {'\r\n','\r'};
new = '\n';
newStr = replace(str,old,new)

newStr = 3x1 string
    "Submission Date: 11/29/15\n"
    "Acceptance Date: 1/20/16\n"
    "Contact: [e-mail]\n"

Input Arguments

str — Input text

string array | character vector | cell array of character vectors

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

old — Substring to replace

string array | character vector | cell array of character vectors | pattern array (since R2020b)

Substring to replace, specified as one of the following:

• String array

• Character vector

• Cell array of character vectors

• pattern array (since R2020b)

new — New substring

string array | character vector | cell array of character vectors

New substring, specified as a string array, character vector, or cell array of character vectors.

Tips

• To perform multiple replacements for overlapping patterns, use the strrep function.

Extended Capabilities

Tall Arrays

Calculate with arrays that have more rows than fit in memory.

Usage notes and limitations:

• Pattern objects are not supported.

For more information, see Tall Arrays.

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations:

• str, old, and new must be a string scalar, a character vector, or a cell array containing not more than one character vector.

Distributed Arrays

Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.

Usage notes and limitations:

• old must be a string array, character vector, or a cell array of character vectors.

For more information, see Run MATLAB Functions with Distributed Arrays (Parallel Computing Toolbox).