How can MATLAB find and replace a word in a text that contains multiple lines?

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E.g. if there is a text file with 57 lines and I want a small change of a word in line 54.
GEORGIOS BEKAS on 23 Dec 2017
can I cleverly point out these points beforehand by using a special character like ',,' and let MATLAB do the job at each iteration?

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Accepted Answer

Image Analyst
Image Analyst on 23 Dec 2017
You forgot to attach the file. So use fgetl() until you read line 57, then use strrep() on that line.
% Have user browse for a file, from a specified "starting folder."
% For convenience in browsing, set a starting folder from which to browse.
startingFolder = 'C:\Program Files\MATLAB';
if ~exist(startingFolder, 'dir')
% If that folder doesn't exist, just start in the current folder.
startingFolder = pwd;
% Get the name of the file that the user wants to use.
defaultFileName = fullfile(startingFolder, '*.*');
[baseFileName, folder] = uigetfile(defaultFileName, 'Select a file');
if baseFileName == 0
% User clicked the Cancel button.
fullFileName = fullfile(folder, baseFileName)
% Open the file.
fileID = fopen(fullFileName, 'rt');
% Read the first line of the file.
textLine = fgetl(fileID);
numLinesRead = 1;
while ischar(textLine)
% Read the remaining lines of the file.
fprintf('%s\n', textLine);
% Read the next line.
textLine = fgetl(fileID);
numLinesRead = numLinesRead + 1;
if numLinesRead == 57
% Use strrep() on textLine
changedLine = strrep(textLine, oldText, newText);
% Then do something with changedLine.
% All done reading all lines, so close the file.

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