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Since a string is a character array, comparisons between strings work element by element as the following example shows:

GNU = "GNU's Not UNIX"; spaces = (GNU == " ") ⇒ spaces = 0 0 0 0 0 1 0 0 0 1 0 0 0 0

To determine if two strings are identical it is necessary to use the
`strcmp`

function. It compares complete strings and is case
sensitive. `strncmp`

compares only the first `N`

characters (with
`N`

given as a parameter). `strcmpi`

and `strncmpi`

are the
corresponding functions for case-insensitive comparison.

- Built-in Function:
**strcmp***(*`s1`,`s2`) Return 1 if the character strings

`s1`and`s2`are the same, and 0 otherwise.If either

`s1`or`s2`is a cell array of strings, then an array of the same size is returned, containing the values described above for every member of the cell array. The other argument may also be a cell array of strings (of the same size or with only one element), char matrix or character string.**Caution:**For compatibility with MATLAB, Octave’s strcmp function returns 1 if the character strings are equal, and 0 otherwise. This is just the opposite of the corresponding C library function.

- Built-in Function:
**strncmp***(*`s1`,`s2`,`n`) Return 1 if the first

`n`characters of strings`s1`and`s2`are the same, and 0 otherwise.strncmp ("abce", "abcd", 3) ⇒ 1

If either

`s1`or`s2`is a cell array of strings, then an array of the same size is returned, containing the values described above for every member of the cell array. The other argument may also be a cell array of strings (of the same size or with only one element), char matrix or character string.strncmp ("abce", {"abcd", "bca", "abc"}, 3) ⇒ [1, 0, 1]

**Caution:**For compatibility with MATLAB, Octave’s strncmp function returns 1 if the character strings are equal, and 0 otherwise. This is just the opposite of the corresponding C library function.

- Built-in Function:
**strcmpi***(*`s1`,`s2`) Return 1 if the character strings

`s1`and`s2`are the same, disregarding case of alphabetic characters, and 0 otherwise.If either

`s1`or`s2`is a cell array of strings, then an array of the same size is returned, containing the values described above for every member of the cell array. The other argument may also be a cell array of strings (of the same size or with only one element), char matrix or character string.**Caution:**For compatibility with MATLAB, Octave’s strcmp function returns 1 if the character strings are equal, and 0 otherwise. This is just the opposite of the corresponding C library function.**Caution:**National alphabets are not supported.

- Built-in Function:
**strncmpi***(*`s1`,`s2`,`n`) Return 1 if the first

`n`character of`s1`and`s2`are the same, disregarding case of alphabetic characters, and 0 otherwise.`s1`or`s2`is a cell array of strings, then an array of the same size is returned, containing the values described above for every member of the cell array. The other argument may also be a cell array of strings (of the same size or with only one element), char matrix or character string.**Caution:**For compatibility with MATLAB, Octave’s strncmpi function returns 1 if the character strings are equal, and 0 otherwise. This is just the opposite of the corresponding C library function.**Caution:**National alphabets are not supported.

- Function File:
`validstr`=**validatestring***(*`str`,`strarray`) - Function File:
`validstr`=**validatestring***(*`str`,`strarray`,`funcname`) - Function File:
`validstr`=**validatestring***(*`str`,`strarray`,`funcname`,`varname`) - Function File:
`validstr`=**validatestring***(…,*`position`) Verify that

`str`is an element, or substring of an element, in`strarray`.When

`str`is a character string to be tested, and`strarray`is a cellstr of valid values, then`validstr`will be the validated form of`str`where validation is defined as`str`being a member or substring of`validstr`. This is useful for both verifying and expanding short options, such as`"r"`

, to their longer forms, such as`"red"`

. If`str`is a substring of`validstr`, and there are multiple matches, the shortest match will be returned if all matches are substrings of each other. Otherwise, an error will be raised because the expansion of`str`is ambiguous. All comparisons are case insensitive.The additional inputs

`funcname`,`varname`, and`position`are optional and will make any generated validation error message more specific.Examples:

validatestring ("r", {"red", "green", "blue"}) ⇒ "red" validatestring ("b", {"red", "green", "blue", "black"}) ⇒ error: validatestring: multiple unique matches were found for 'b': blue, black

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