After a search you might want to perform a replace operation within the matches, for example to rename a function or add a missing package prefix throughout your source code.
To do this, press 
or choose
Query Replace...
from the context menu in the results area to raise the
Query replace in matched lines
dialog.
Figure 16.5 The Query replace in matched lines dialog
Enter a regular expression to replace in the Regexp to replace: box. Enter the replacment text in the Replace by: box, and press OK .
For each of the matched lines that also matches the regular expression, an Editor tool displays the file with a prompt in the Echo Area. Type 'y' or 'n' to make the replacement or not, for each match in turn.
Save the modified the editor buffers (see Opening, saving and printing files) to commit your replacements to disk.