Mô đun:String/tài liệu

This module is intended to provide access to basic string functions.
Most of the functions provided here can be invoked with named parameters, unnamed parameters, or a mixture.  If named parameters are used, Mediawiki will automatically remove any leading or trailing whitespace from the parameter. Depending on the intended use, it may be advantageous to either preserve or remove such whitespace.

**Global options**
 ignore_errors
 If set to 'true' or 1, any error condition will result in an empty string being returned rather than an error message.
 error_category
 If an error occurs, specifies the name of a category to include with the error message.  The default category is Errors reported by Module String.
 no_category
 If set to 'true' or 1, no category will be added if an error is generated.
Unit tests for this module are available at Module:String/testcases.

**len**
This function returns the length of the target string.
Usage:
 String|len|target_string
OR
 String|len|s= target_string 
Parameters:
 s
 The string whose length to report
Examples:-  →  abcdefghi -  → s= abcdefghi 

**sub**
This function returns a substring of the target string at specified inclusive, one-indexed indices.
Usage:
 String|sub|target_string|start_index|end_index
OR
 String|sub|s= target_string |i= start_index |j= end_index 
Parameters:
 s
 The string to return a subset of
 i
 The first index of the substring to return, defaults to 1.
 j
 The last index of the string to return, defaults to the last character.
The first character of the string is assigned an index of 1.  If either i or j is a negative value, it is interpreted the same as selecting a character by counting from the end of the string.  Hence, a value of -1 is the same as selecting the last character of the string.
If the requested indices are out of range for the given string, an error is reported. To avoid error messages, use sub instead.
Examples:-  → " abcdefghi "-  → "s= abcdefghi "-  → " 3 "-  → "i= 3 "-  → " 4 "-  → "j= 4 "

**sublength**
This function implements the features of str sub old and is kept in order to maintain these older templates. It returns a substring of the target string starting at a specified index and of a specified length.
Usage:
 String|sublength|s= target_string |i= start_index |len= length 
Parameters:
 s
 The string
 i
 The starting index of the substring to return. The first character of the string is assigned an index of 0.
 len
 The length of the string to return, defaults to the last character.
Examples:-  → s= abcdefghi -  → i= 3 -  → len= 4 

**match**
This function returns a substring from the source string that matches a specified pattern.
Usage:
 String|match|source_string|pattern_string|start_index|match_number|plain_flag|nomatch_output
OR
 String|match|s= source_string |pattern= pattern_string |start= start_index |match= match_number |plain= plain_flag |nomatch= nomatch_output 
Parameters:
 s
 The string to search
 pattern
 The pattern or string to find within the string
 start
 The index within the source string to start the search.  The first character of the string has index 1.  Defaults to 1.
 match
 In some cases it may be possible to make multiple matches on a single string.  This specifies which match to return, where the first match is match= 1.  If a negative number is specified then a match is returned counting from the last match.  Hence match = -1 is the same as requesting the last match.  Defaults to 1.
 plain
 Boolean flag indicating that pattern should be understood as plain text and not as a Scribunto ustring pattern (a unicode-friendly Lua-style regular expression). Defaults to false (to change: plain=true)
 nomatch
 If no match is found, output the "nomatch" value rather than an error.
 ignore_errors
 If no match is found and ignore_errors=true, output an empty string rather than an error.
If the match_number or start_index are out of range for the string being queried, then this function generates an error.  An error is also generated if no match is found.
If one adds the parameter ignore_errors=true, then the error will be suppressed and an empty string will be returned on any failure.
For information on constructing Lua patterns, a form of regular expression, see:- Scribunto patterns- Scribunto Unicode string patterns
Examples:-  → %d+-  → pattern= %d+ -  → 6-  → start= 6 -  → match= 2 -  → pattern= %d+ -  → plain= true -  → no_category=true-  → nomatch= No numeric characters in string -  → ignore_errors= true -  → pattern= 0*(%d*) 

**pos**
This function returns a single character from the target string at position pos.
Usage:
 String|pos|target_string|index_value
OR
 String|pos|target= target_string |pos= index_value 
Parameters:
 target
 The string to search
 pos
 The index for the character to return
The first character has an index value of 1.
If one requests a negative value, this function will select a character by counting backwards
from the end of the string.  In other words pos = -1 is the same as asking for the last character.
A requested value of zero, or a value greater than the length of the string returns an error.
Examples:-  →  4 -  → pos= 4 

**str_find**
This function duplicates the behavior of str_find, including all of its quirks. This is provided in order to support existing templates, but is NOT RECOMMENDED for new code and templates.  New code is recommended to use the "find" function instead.
Returns the first index in "source" that is a match to "target".  Indexing is 1-based, and the function returns -1 if the "target" string is not present in "source".
Important Note: If the "target" string is empty / missing, this function returns a value of "1", which is generally unexpected behavior, and must be accounted for separately.
Usage:
 String|str_find|source_string|target_string
OR
 String|str_find|source= source_string |target= target_string 
Parameters:
 source
 The string to search
 target
 The string to find within source
Examples:-  →  abc123def -  → source= abc123def -  → 123-  → target= 123 -  → not

**find**
This function allows one to search for a target string or pattern within another string.
Usage:
 String|find|source_string|target_string|start_index|plain_flag
OR
 String|find|source= source_string |target= target_string |start= start_index |plain= plain_flag 
Parameters:
 source
 The string to search
 target
 The string or pattern to find within source
 start
 The index within the source string to start the search, defaults to 1
 plain
 Boolean flag indicating that target should be understood as plain text and not as a Scribunto ustring pattern (a unicode-friendly Lua-style regular expression); defaults to true
This function returns the first index >= "start" where "target" can be found within "source".  Indices are 1-based.  If "target" is not found, then this function returns 0.  If either "source" or "target" are missing / empty, this function also returns 0.
This function should be safe for UTF-8 strings.
Examples:-  → 12-  → target=12-  → target=pqr-  → 123-  → target= 123 -  → plain=false 
When using unnamed parameters, preceding and trailing spaces are kept and counted:-  → false-  → plain=false-  → plain=false

**replace (gsub)**
This function allows one to replace a target string or pattern within another string. To Lua programmers: this function works internally by calling string.gsub.
Usage:
 String|replace|source_str|pattern_string|replace_string|replacement_count|plain_flag
OR
 String|replace|source= source_string |pattern= pattern_string |replace= replace_string |count= replacement_count |plain= plain_flag 
Parameters:
 source
 The string to search
 pattern
 The string or pattern to find within source
 replace
 The replacement text
 count
 The number of occurrences to replace; defaults to all
 plain
 Boolean flag indicating that pattern should be understood as plain text and not as a Scribunto ustring pattern (a unicode-friendly Lua-style regular expression); defaults to true
Examples:-  → "N"-  → "replace= N "-  → "false"-  → "plain= false "-  → "plain= false "-  → plain= false 

**rep**
Repeats a string n times. A simple function to pipe string.rep to templates.
Usage:
 String|rep|source|count
Parameters:
 source
 The string to repeat
 count
 The number of repetitions.
Examples:-  → "3"-  → " 3 "

**escapePattern**
In a Lua pattern, changes a class character into a literal character. For example: in a pattern, character . catches "any character"; escapePattern will convert it to %., catching just the literal character ".".
Usage:- pattern_string
Parameters:
 pattern_string
 The pattern string to escape
Examples:-  → "A.D."-  → "10%"

**count == 
Counts the number of times a given pattern appears in the arguments that get passed on to this module. 
Usage:
 String|count|source_str|pattern_string|plain_flag
OR
 String|count|source= source_string |pattern= pattern_string|plain= plain_flag 
Parameters:
 source_string
 The string to count occurrences in
 pattern
 The string or pattern to count occurrences of within source
 plain
 Boolean flag indicating that pattern should be understood as plain text and not as a Scribunto ustring pattern (a unicode-friendly Lua-style regular expression); defaults to true
Examples:- Count of 'a':  → "a"- Count of "either 'a' or 'c' ": → "#invoke:String|count|aabbcc|ac|plain=false"- Count of "not 'a' ":  → "#invoke:String|count|aaabaaac|^a|plain=false"- Count of "starts with 'a' ":  → "plain=false"

**join**
Joins all strings passed as arguments into one string, treating the first argument as a separator
Usage:
 String|join|separator|string1|string2|...
Parameters:
 separator
 String that separates each string being joined together
 Note that leading and trailing spaces are not stripped from the separator.
 string1/string2/...
 Strings being joined together
Examples:-  → "baz"-  → "g"-  → "g"-  → "g"-  → "g"
The preceding example uses the html entity &ndash; but the unicode character also works.

**endswith**
Usage:
 String|endswith|source_str|search_string
OR
 String|endswith|source= source_string |pattern= search_string
Returns "yes" if the source string ends with the search string. Use named parameters to have the strings trimmed before use. Despite the parameter name, search_string is not a Lua pattern, it is interpreted literally.-  → "y"-  → "z"

**See also==