PyCharm 2019.2 Help

Find and replace a string using regular expressions

When you want to search and replace specific patterns of text, use regular expressions. They can help you in pattern matching, parsing, filtering of results, and so on. Once you learn the regex syntax, you can use it for almost any language.

  1. Press Ctrl+R to open the search and replace pane.

  2. Select the Regex checkbox to enable the regex syntax. If you need to check the regex syntax reference, click the question mark next to the Regex.

  3. Enter a search string in the top field and a replace string in the bottom field.

    Regex search and replace fields
  4. When you search for metacharacters such as .[{()\^$|?*+, you need to escape them with backslash \, so they can be recognized.

    For example, if you need to find ., type \. in the search field.

  5. PyCharm can also match a letter case when you enter a range of characters in your search field.

    For example, if you want to search for only uppercase characters, type the following in the search field:

    \b[A-Z]
  6. If the Match Case checkbox is cleared, PyCharm searches for both lower and upper cases. Select the Match Case checkbox to match the case of the specified range.

    The result of the Match Case selection

  7. When you browse the occurrences, PyCharm displays the replacement hints, so you can view the potential results before clicking the Replace button.

    Replacement hints

Use regex capturing groups and backreferences

You can put the regular expressions inside brackets in order to group them. Each group has a number starting with 1, so you can refer to (backreference) them in your replace pattern. Note that the group 0 refers to the entire regular expression.

Let's consider the following code:

<form action="" class="form-inline" method="post"> <input type="text" class="form-control" name="username" value="Username"> <input type="password" class="form-control" name="password" value="Password"> <input class="btn btn-default" type="submit" value="Login"> </form>
  1. Open the search and replace pane Ctrl+R.

  2. In the search field, enter parentheses () that would indicate a capturing group, for example: \svalue="(.*)?"\s*(>*)

  3. In the replace field, backreference such groups by numbers starting with 1, for example: placeholder="$1"

  4. PyCharm highlights the found occurrences based on your search specifications and displays hints with the replace string.

    Replace with regex result

Switch the character case

You can use regular expressions to change the case of characters that matches some criteria.

  1. Open the search and replace pane Ctrl+R. Make sure that the Regex checkbox is selected.

  2. In the search field enter the search pattern.

  3. In the replace field, depending on what you want to achieve, enter one of the following syntax:

    • \l changes a character to lowercase until the next character in the string.
      For example, Bar becomes bar.

    • \u changes a character to uppercase until the next character in the string.
      For example, bar becomes Bar.

    • \L changes characters to lowercase until the end of the literal string \E.
      For example, BAR becomes bar.

    • \U changes characters to uppercase until the end of the literal string \E.
      For example, bar becomes BAR.

    Switch to the uppercase character example

Refer to the RegEx syntax reference table for more details.

Last modified: 14 October 2019