How to Add property _value pairs to a txt file and sort them alphabetically

Question

I want to add property-values pair in a txt file which contains property-values pairs and the properties should be sorted alphabetically, where a property is between square brackets and its value in the line below. This is an example file: On top of that i want to ignore the comment lines started with '#'.

#
[system]
# 
programming 
#
[information] 
#
application

Like:-

function [] = updateFile( fileName,property,propertyValue )

% all inputs in strings
%
rfh = fopen( fileName, 'r' ); % read handle
tname = tempname(); % temporary file name
wfh = fopen( tname, 'w' )

In this example, ´system´ is a property and ´programming´ its value. The same way, ´information´ is another property and ´application´ its value.

I want to call my function with a property-value pair and update the txt file with the new property-value pairs.

Answer 1

Since you are updating a file you should open it in "append" mode. You use the sort function to sort your data. Assuming the variables property and propertyValue are cell arrays, your code would look something like this

function [] = updateFile( fileName,property,propertyValue )

% all inputs in strings

fid = fopen(fileName, 'a' ); % file handle
[property_sorted,sort_index] = sort(property); % sort file
for count = 1:length(sort_index)
    fprintf(fid,'%s\n%s\n',property_sorted(count),propertyValue(sort_index(count)));
end

fclose(fid);

See the documentation for sort (doc sort) for more information.