String operations.
Search and Replace string(FIND <string> <substring> <out-var> [...]) string(REPLACE <match-string> <replace-string> <out-var> <input>...) 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 <string> <out-var>) string(TOUPPER <string> <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>) string(REPEAT <string> <count> <out-var>) Comparison string(COMPARE <op> <string1> <string2> <out-var>) Hashing string(<HASH> <out-var> <input>) Generation string(ASCII <number>... <out-var>) string(HEX <string> <out-var>) string(CONFIGURE <string> <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> ...)
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.
The string(FIND) subcommand treats all strings as ASCII-only characters.
The index stored in <output_variable> will also be counted in bytes,
so strings containing multi-byte characters may lead to unexpected results.
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_variable>.
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.
Regular expressions are specified in the subsection just below.
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.
string(REGEX REPLACE <regular_expression>
<replacement_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 <replacement_expression> may refer to parenthesis-delimited
subexpressions of the match using 1円, 2円, ..., 9円. Note that
two backslashes (\1円) are required in CMake code to get a backslash
through argument parsing.
The following characters have special meaning in regular expressions:
^$.\<char><char>. Use this to
match special regex characters, e.g. \. for a literal .
or \\ for a literal backslash \. Escaping a non-special
character is unnecessary but allowed, e.g. \a matches a.[ ][^ ]-[a-f] is [abcdef]
To match a literal - using brackets, make it the first
or the last character e.g. [+*/-] matches basic
mathematical operators.*+?||
()REGEX REPLACE operation. Additionally it is saved
by all regular expression-related commands, including
e.g. :command:`if(MATCHES)`, in the variables
:variable:`CMAKE_MATCH_<n>` for <n> 0..9.*, + and ? have higher precedence than concatenation. |
has lower precedence than concatenation. This means that the regular
expression ^ab+d$ 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:
"[ \t\r\n]" specifies a regex that matches
any single whitespace character."[/\\]" specifies a regex that matches
a single forward slash / or backslash \."[A-Za-z0-9_]" specifies a regex that matches
any single "word" character in the C locale."\\(\\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. [[\(\a\+\b\)]].
string(APPEND <string_variable> [<input>...])
Append all the <input> arguments to the string.
string(PREPEND <string_variable> [<input>...])
Prepend all the <input> arguments to the string.
string(CONCAT <output_variable> [<input>...])
Concatenate all the <input> arguments together and store
the result in the named <output_variable>.
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 a list's elements, prefer to use the JOIN operator
from the :command:`list` command. This allows for the elements to have
special characters like ; in them.
string(TOLOWER <string> <output_variable>)
Convert <string> to lower characters.
string(TOUPPER <string> <output_variable>)
Convert <string> to upper characters.
string(LENGTH <string> <output_variable>)
Store in an <output_variable> a given string's length in bytes.
Note that this means if <string> contains multi-byte characters, the
result stored in <output_variable> will not be the number of characters.
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 the
end of the string is used instead.
Both <begin> and <length> are counted in bytes, so care must
be exercised if <string> could contain multi-byte characters.
Note
CMake 3.1 and below reported an error if <length> pointed past
the end of <string>.
string(STRIP <string> <output_variable>)
Store in an <output_variable> a substring of a given <string> with
leading and trailing spaces removed.
string(GENEX_STRIP <string> <output_variable>)
Strip any :manual:`generator expressions <cmake-generator-expressions(7)>`
from the input <string> and store the result in the <output_variable>.
string(REPEAT <string> <count> <output_variable>)
Produce the output string as the input <string> repeated <count> times.
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>.
string(<HASH> <output_variable> <input>)
Compute a cryptographic hash of the <input> string.
The supported <HASH> algorithm names are:
MD5SHA1SHA224SHA256SHA384SHA512SHA3_224SHA3_256SHA3_384SHA3_512
string(ASCII <number> [<number> ...] <output_variable>)
Convert all numbers into corresponding ASCII characters.
string(HEX <string> <output_variable>)
Convert each byte in the input <string> to its hexadecimal representation
and store the concatenated hex digits in the <output_variable>. Letters in
the output (a through f) are in lowercase.
string(CONFIGURE <string> <output_variable>
[@ONLY] [ESCAPE_QUOTES])
Transform a <string> like :command:`configure_file` transforms a file.
string(MAKE_C_IDENTIFIER <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.
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.
string(TIMESTAMP <output_variable> [<format_string>] [UTC])
Write a string representation of the current date
and/or time to the <output_variable>.
If the command is 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 Create a universally unique identifier (aka GUID) as per RFC4122
based on the hash of the combined values of SOURCE_DATE_EPOCH environment variable is set,
its value will be used instead of the current time.
See
string(UUID <output_variable> NAMESPACE <namespace> NAME <name>
TYPE <MD5|SHA1> [UPPER])
<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.
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