MATLAB: How to get MATLAB to compare strings in the same way as the strcmp(str1,str2) method in the ANSI C API

comparecomparisonMATLABstrcmpstringstring compare

I would like to perform string comparisons between strings that possibly have differing lengths that is consistent with the C API call of the STRCMP method in C with this signature:

int strcmp ( const char * str1, const char * str2 );

I expect the function to perform as follows:

Return 0 if the strings are identical

Return 1 if the ASCII value of the first non-matching character of string 1 is greater than string 2.

Return -1 if the ASCII value of the first non-matching character of string 1 is less than string 2.

strcmp('ibm','ibn')
strcmp('orcl','ibm')

should return '-1' and '1' respectively.

Best Answer

STRCMP in MATLAB performs a character-wise comparison of strings, but does not provide more information regarding the match.

To work around this issue, there are useful third-party submissions at the MathWorks File Exchange that perform string-comparison in the same way as the C API. These files can be downloaded at the following location and saved to a MATLAB path directory:

https://www.mathworks.com/matlabcentral/fileexchange/3987-compare-strings-c-convention

https://www.mathworks.com/matlabcentral/fileexchange/23035-lexcmp

https://www.mathworks.com/matlabcentral/fileexchange/18347-c-style-string-comparisons

https://www.mathworks.com/matlabcentral/fileexchange/16894-strrel

https://www.mathworks.com/matlabcentral/fileexchange/23375-string-comparison

Note that MathWorks does not guarantee or warrant the use or content of these submissions. Any questions, issues, or complaints should be directed to the contributing author.

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Use the 'strsplit' function to split a string by specifying the '|' character as a delimiter. We can also use the 'cellfun' function to repeat the 'strsplit' function on each cell of a cell array. The code below demonstrates the use of the two functions to achieve the output you require (A is the initial one column cell array).

>> newA = cellfun(@(x) strsplit(x, '|'), A, 'UniformOutput', false);

>> newA = vertcat(newA{:}); % To remove nesting of cell array newA

For more information regarding the use of the above mentioned function, please refer to the documentation links below:

https://www.mathworks.com/help/matlab/ref/strsplit.html

https://www.mathworks.com/help/matlab/ref/cellfun.html

https://www.mathworks.com/help/matlab/matlab_prog/anonymous-functions.html

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Floating point variables do not have leading 0's physically stored in memory (not counting the denormalized numbers of course). So 0001 and 1 are stored exactly the same in memory. If you want to display the leading 0's then you need to use a format that specifies that on print out. E.g.,

>> day = '0001'
day =
0001
>> d = str2double(day)
d =
     1
>> fprintf('%04d\n',d)
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