Next Available Filename

Returns the next unused file or folder name. The name is created by incrementing a numbered suffix.

NEXTNAME returns a file or folder name, incrementing a numbered suffix such that the returned name is not currently used by any file or folder.

On occasion it may be required to save files without knowing or requiring a particular number sequence, for example when saving interim results or backups during large calculations. Using an internal counter is one option, but this does not work when there are already existing files with those names, or when the code is stopped-and-started, or throws errors while calculating. This function offers one simple solution: call the function with the required file (or folder) name, the required suffix (including the starting integer) and the file extension (if any), and it will return the next unused name.

Note that unlike some other submissions on FEX, this function compares the number *values*, not the literal filenames! This means you will not get "x001" if e.g. "x1" or "x01" or "x00000001" already exist in the specified location.

Inputs

Three text inputs are required (may be string scalars or char vectors):

1. The basic file or folder name, without the file extension (if any). If the location to be checked for existing files is not the current directory then the basic name must use a relative or absolute path to that location.

2. The suffix, which must contain the starting number. Some examples of suffixes are: '0', '_1', '(5)', '-0001-backup', '_temp1', etc.. This suffix will be appended to the file/folder name (before the file extension), and the number will be incremented to identify the first unused name starting from the number provided in the suffix. Thus the suffix defines:

* the starting value (can be zero or any positive integer, i.e. 0, 1, 2, 3, etc.).

* the minimum length of the output number (use leading zeros as required).

* any literal characters.

3. The file extension, if required. For folders and files without extensions use '' or "".

Note the inputs 1 and 3 are easily obtained from a filename using FILEPARTS

Examples

%% Current directory contains files 'A1.txt', 'A2.txt', and 'A4.txt':
>> nextname("A","1",".txt")
ans = "A3.txt"
>> nextname("A","001",".txt")
ans = "A003.txt"
%% Subdirectory 'HTML' contains folders 'B(1)', 'B(2)', and 'B(4)':
>> nextname('HTML/B','(1)','')
ans = 'B(3)'
>> nextname('HTML/B','(001)','')
ans = 'B(003)'
>> nextname('HTML/B','(1)','',false) % default = name only.
ans = 'B(3)'
>> nextname('HTML/B','(1)','',true) % with the path from the input name.
ans = 'HTML/B(3)'