string ------ String operations. Synopsis ^^^^^^^^ .. parsed-literal:: `Search and Replace`_ string(`FIND`_ <string> <substring> <out-var> [...]) string(`REPLACE`_ <match-string> <replace-string> <out-var> <input>...) `Regular Expressions`_ string(`REGEX MATCH`_ <match-regex> <out-var> <input>...) string(`REGEX MATCHALL`_ <match-regex> <out-var> <input>...) string(`REGEX REPLACE`_ <match-regex> <replace-expr> <out-var> <input>...) `Manipulation`_ string(`APPEND`_ <string-var> [<input>...]) string(`PREPEND`_ <string-var> [<input>...]) string(`CONCAT`_ <out-var> [<input>...]) string(`JOIN`_ <glue> <out-var> [<input>...]) string(`TOLOWER`_ <string1> <out-var>) string(`TOUPPER`_ <string1> <out-var>) string(`LENGTH`_ <string> <out-var>) string(`SUBSTRING`_ <string> <begin> <length> <out-var>) string(`STRIP`_ <string> <out-var>) string(`GENEX_STRIP`_ <string> <out-var>) `Comparison`_ string(`COMPARE`_ <op> <string1> <string2> <out-var>) `Hashing`_ string(`\<HASH\> <HASH_>`_ <out-var> <input>) `Generation`_ string(`ASCII`_ <number>... <out-var>) string(`CONFIGURE`_ <string1> <out-var> [...]) string(`MAKE_C_IDENTIFIER`_ <string> <out-var>) string(`RANDOM`_ [<option>...] <out-var>) string(`TIMESTAMP`_ <out-var> [<format string>] [UTC]) string(`UUID`_ <out-var> ...) Search and Replace ^^^^^^^^^^^^^^^^^^ .. _FIND: .. code-block:: cmake string(FIND <string> <substring> <output variable> [REVERSE]) Return the position where the given substring was found in the supplied string. If the ``REVERSE`` flag was used, the command will search for the position of the last occurrence of the specified substring. If the substring is not found, a position of -1 is returned. .. _REPLACE: .. code-block:: cmake string(REPLACE <match_string> <replace_string> <output variable> <input> [<input>...]) Replace all occurrences of ``match_string`` in the input with ``replace_string`` and store the result in the output. Regular Expressions ^^^^^^^^^^^^^^^^^^^ .. _`REGEX MATCH`: .. code-block:: cmake string(REGEX MATCH <regular_expression> <output variable> <input> [<input>...]) Match the regular expression once and store the match in the output variable. All ``<input>`` arguments are concatenated before matching. .. _`REGEX MATCHALL`: .. code-block:: cmake string(REGEX MATCHALL <regular_expression> <output variable> <input> [<input>...]) Match the regular expression as many times as possible and store the matches in the output variable as a list. All ``<input>`` arguments are concatenated before matching. .. _`REGEX REPLACE`: .. code-block:: cmake string(REGEX REPLACE <regular_expression> <replace_expression> <output variable> <input> [<input>...]) Match the regular expression as many times as possible and substitute the replacement expression for the match in the output. All ``<input>`` arguments are concatenated before matching. The replace expression may refer to paren-delimited subexpressions of the match using ``\1``, ``\2``, ..., ``\9``. Note that two backslashes (``\\1``) are required in CMake code to get a backslash through argument parsing. .. _`Regex Specification`: Regex Specification """"""""""""""""""" The following characters have special meaning in regular expressions: ``^`` Matches at beginning of input ``$`` Matches at end of input ``.`` Matches any single character ``\<char>`` Matches the single character specified by ``<char>``. Use this to match special regex characters, e.g. ``\.`` for a literal ``.`` or ``\\`` for a literal backslash ``\``. Escaping a non-special character is unnecessary but allowed, e.g. ``\a`` matches ``a``. ``[ ]`` Matches any character(s) inside the brackets ``[^ ]`` Matches any character(s) not inside the brackets ``-`` Inside brackets, specifies an inclusive range between characters on either side e.g. ``[a-f]`` is ``[abcdef]`` To match a literal ``-`` using brackets, make it the first or the last character e.g. ``[+*/-]`` matches basic mathematical operators. ``*`` Matches preceding pattern zero or more times ``+`` Matches preceding pattern one or more times ``?`` Matches preceding pattern zero or once only ``|`` Matches a pattern on either side of the ``|`` ``()`` Saves a matched subexpression, which can be referenced in the ``REGEX REPLACE`` operation. Additionally it is saved by all regular expression-related commands, including e.g. :command:`if(MATCHES)`, in the variables :variable:`CMAKE_MATCH_<n>` for ``<n>`` 0..9. ``*``, ``+`` and ``?`` have higher precedence than concatenation. ``|`` has lower precedence than concatenation. This means that the regular expression ``^ab+d$`` matches ``abbd`` but not ``ababd``, and the regular expression ``^(ab|cd)$`` matches ``ab`` but not ``abd``. CMake language :ref:`Escape Sequences` such as ``\t``, ``\r``, ``\n``, and ``\\`` may be used to construct literal tabs, carriage returns, newlines, and backslashes (respectively) to pass in a regex. For example: * The quoted argument ``"[ \t\r\n]"`` specifies a regex that matches any single whitespace character. * The quoted argument ``"[/\\]"`` specifies a regex that matches a single forward slash ``/`` or backslash ``\``. * The quoted argument ``"[A-Za-z0-9_]"`` specifies a regex that matches any single "word" character in the C locale. * The quoted argument ``"\\(\\a\\+b\\)"`` specifies a regex that matches the exact string ``(a+b)``. Each ``\\`` is parsed in a quoted argument as just ``\``, so the regex itself is actually ``\(\a\+\b\)``. This can alternatively be specified in a :ref:`bracket argument` without having to escape the backslashes, e.g. ``[[\(\a\+\b\)]]``. Manipulation ^^^^^^^^^^^^ .. _APPEND: .. code-block:: cmake string(APPEND <string variable> [<input>...]) Append all the input arguments to the string. .. _PREPEND: .. code-block:: cmake string(PREPEND <string variable> [<input>...]) Prepend all the input arguments to the string. .. _CONCAT: .. code-block:: cmake string(CONCAT <output variable> [<input>...]) Concatenate all the input arguments together and store the result in the named output variable. .. _JOIN: .. code-block:: cmake string(JOIN <glue> <output variable> [<input>...]) Join all the input arguments together using the glue string and store the result in the named output variable. To join list's elements, use preferably the ``JOIN`` operator from :command:`list` command. This allows for the elements to have special characters like ``;`` in them. .. _TOLOWER: .. code-block:: cmake string(TOLOWER <string1> <output variable>) Convert string to lower characters. .. _TOUPPER: .. code-block:: cmake string(TOUPPER <string1> <output variable>) Convert string to upper characters. .. _LENGTH: .. code-block:: cmake string(LENGTH <string> <output variable>) Store in an output variable a given string's length. .. _SUBSTRING: .. code-block:: cmake string(SUBSTRING <string> <begin> <length> <output variable>) Store in an output variable a substring of a given string. If length is ``-1`` the remainder of the string starting at begin will be returned. If string is shorter than length then end of string is used instead. .. note:: CMake 3.1 and below reported an error if length pointed past the end of string. .. _STRIP: .. code-block:: cmake string(STRIP <string> <output variable>) Store in an output variable a substring of a given string with leading and trailing spaces removed. .. _GENEX_STRIP: .. code-block:: cmake string(GENEX_STRIP <input string> <output variable>) Strip any :manual:`generator expressions <cmake-generator-expressions(7)>` from the ``input string`` and store the result in the ``output variable``. Comparison ^^^^^^^^^^ .. _COMPARE: .. code-block:: cmake string(COMPARE LESS <string1> <string2> <output variable>) string(COMPARE GREATER <string1> <string2> <output variable>) string(COMPARE EQUAL <string1> <string2> <output variable>) string(COMPARE NOTEQUAL <string1> <string2> <output variable>) string(COMPARE LESS_EQUAL <string1> <string2> <output variable>) string(COMPARE GREATER_EQUAL <string1> <string2> <output variable>) Compare the strings and store true or false in the output variable. .. _`Supported Hash Algorithms`: Hashing ^^^^^^^ .. _`HASH`: .. code-block:: cmake string(<HASH> <output variable> <input>) Compute a cryptographic hash of the input string. The supported ``<HASH>`` algorithm names are: ``MD5`` Message-Digest Algorithm 5, RFC 1321. ``SHA1`` US Secure Hash Algorithm 1, RFC 3174. ``SHA224`` US Secure Hash Algorithms, RFC 4634. ``SHA256`` US Secure Hash Algorithms, RFC 4634. ``SHA384`` US Secure Hash Algorithms, RFC 4634. ``SHA512`` US Secure Hash Algorithms, RFC 4634. ``SHA3_224`` Keccak SHA-3. ``SHA3_256`` Keccak SHA-3. ``SHA3_384`` Keccak SHA-3. ``SHA3_512`` Keccak SHA-3. Generation ^^^^^^^^^^ .. _ASCII: .. code-block:: cmake string(ASCII <number> [<number> ...] <output variable>) Convert all numbers into corresponding ASCII characters. .. _CONFIGURE: .. code-block:: cmake string(CONFIGURE <string1> <output variable> [@ONLY] [ESCAPE_QUOTES]) Transform a string like :command:`configure_file` transforms a file. .. _MAKE_C_IDENTIFIER: .. code-block:: cmake string(MAKE_C_IDENTIFIER <input string> <output variable>) Convert each non-alphanumeric character in the ``<input string>`` to an underscore and store the result in the ``<output variable>``. If the first character of the string is a digit, an underscore will also be prepended to the result. .. _RANDOM: .. code-block:: cmake string(RANDOM [LENGTH <length>] [ALPHABET <alphabet>] [RANDOM_SEED <seed>] <output variable>) Return a random string of given length consisting of characters from the given alphabet. Default length is 5 characters and default alphabet is all numbers and upper and lower case letters. If an integer ``RANDOM_SEED`` is given, its value will be used to seed the random number generator. .. _TIMESTAMP: .. code-block:: cmake string(TIMESTAMP <output variable> [<format string>] [UTC]) Write a string representation of the current date and/or time to the output variable. Should the command be unable to obtain a timestamp the output variable will be set to the empty string "". The optional ``UTC`` flag requests the current date/time representation to be in Coordinated Universal Time (UTC) rather than local time. The optional ``<format string>`` may contain the following format specifiers: :: %% A literal percent sign (%). %d The day of the current month (01-31). %H The hour on a 24-hour clock (00-23). %I The hour on a 12-hour clock (01-12). %j The day of the current year (001-366). %m The month of the current year (01-12). %b Abbreviated month name (e.g. Oct). %B Full month name (e.g. October). %M The minute of the current hour (00-59). %s Seconds since midnight (UTC) 1-Jan-1970 (UNIX time). %S The second of the current minute. 60 represents a leap second. (00-60) %U The week number of the current year (00-53). %w The day of the current week. 0 is Sunday. (0-6) %a Abbreviated weekday name (e.g. Fri). %A Full weekday name (e.g. Friday). %y The last two digits of the current year (00-99) %Y The current year. Unknown format specifiers will be ignored and copied to the output as-is. If no explicit ``<format string>`` is given it will default to: :: %Y-%m-%dT%H:%M:%S for local time. %Y-%m-%dT%H:%M:%SZ for UTC. .. note:: If the ``SOURCE_DATE_EPOCH`` environment variable is set, its value will be used instead of the current time. See https://reproducible-builds.org/specs/source-date-epoch/ for details. .. _UUID: .. code-block:: cmake string(UUID <output variable> NAMESPACE <namespace> NAME <name> TYPE <MD5|SHA1> [UPPER]) Create a universally unique identifier (aka GUID) as per RFC4122 based on the hash of the combined values of ``<namespace>`` (which itself has to be a valid UUID) and ``<name>``. The hash algorithm can be either ``MD5`` (Version 3 UUID) or ``SHA1`` (Version 5 UUID). A UUID has the format ``xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx`` where each `x` represents a lower case hexadecimal character. Where required an uppercase representation can be requested with the optional ``UPPER`` flag.