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Extended String Module

Extended String Module - string​

Functions marked with 🔤 process the input string type as UTF-8 text.

Convert to Hexadecimal Text (string.to_hex)​

Declaration​

hexadecimal_text = string.to_hex(data_content)

Parameters and Return Values​

  • data_content string
  • hexadecimal_text text

Description​

Converts data_content into printable hexadecimal text.

Example 1​

string.to_hex
sys.alert(string.to_hex('some data'))
-- Output: "e4b880e4ba9be695b0e68dae"

Example 2​

string.to_hex
sys.alert((string.to_hex('some data'):gsub('(..)', '\\x%1')))
-- Output: "\xe4\xb8\x80\xe4\xba\x9b\xe6\x95\xb0\xe6\x8d\xae"

Convert Hexadecimal Text Back (string.from_hex)​

Declaration​

data_content = string.from_hex(hexadecimal_text)

Parameters and Return Values​

  • hexadecimal_text text
  • data_content
    • string, returns nil if the input parameter is not hexadecimal text.

Description​

The inverse function of string.to_hex, converts printable hexadecimal text back to data_content.

Example​

string.from_hex
sys.alert(string.from_hex('e4b880e4ba9be695b0e68dae'))
-- Output: "some data"

Convert GBK Encoded Text to UTF-8 Encoded Text (string.from_gbk)​

Declaration​

usable_text = string.from_gbk(gbk_encoded_string)

Parameters and Return Values​

  • gbk_encoded_string string
  • usable_text
    • text, returns UTF-8 encoded text. If encoding errors prevent conversion, returns nil.

Description​

Converts GBK/GB2312 encoded text to UTF-8 encoded text.

caution

Conversion returning garbled text may be due to incorrect encoding, but the function is not at fault if the conversion completes.

Example​

string.from_gbk
-- Chinese encoding Chinese standard encoding National standard extended encoding GB2312
gbkstr = '\x58\x58\x54\x6f\x75\x63\x68\x20\xba\xdc\xc7\xbf'
--
sys.alert(gbkstr)                  -- GBK encoded string cannot be displayed
sys.alert(string.from_gbk(gbkstr)) -- Output: "XXTouch is strong"

Calculate String Hash Value (string.md5,sha1,sha256,sha512)​

Declaration​

hash_value = string.md5(data_content)     -- Calculate MD5
hash_value = string.sha1(data_content)    -- Calculate SHA-1
hash_value = string.sha256(data_content)  -- Calculate SHA-256
hash_value = string.sha512(data_content)  -- Calculate SHA-512

Parameters and Return Values​

  • data_content string
  • hash_value
    • text, returns the hexadecimal text of the specified type hash value of data_content

Example​

string.md5
sys.alert(string.md5('XXTouch is awesome'))   -- Output: "4921dbf380df452fa959dc47cef30e4b"
string.sha1
sys.alert(string.sha1('XXTouch is awesome'))  -- Output: "a959c48d904c1075c7ddfdb1fda49effb2142493"
string.hash
local str = "sozereal"
sys.alert('The hexadecimal encoding of "'..str..'" is: <'..str:to_hex()..'>')
sys.alert('The plaintext of <'..str:to_hex()..'> is: "'..str:to_hex():from_hex()..'"')
sys.alert('The MD5 value of "'..str..'" is: '..str:md5())
sys.alert('The SHA1 value of "'..str..'" is: '..str:sha1())
local binstr = "\0\1\2\3\4\5"
sys.alert('The MD5 value of <'..binstr:to_hex()..'> is: '..binstr:md5())
sys.alert('The SHA1 value of <'..binstr:to_hex()..'> is: '..binstr:sha1())

Base64 Encode and Decode Strings (string.base64_encode,decode)​

Declaration​

b64_text = string.base64_encode(data_content)  -- Encode
data_content = string.base64_decode(b64_text)  -- Decode

Parameters and Return Values​

  • data_content string
  • b64_text
    • text, the base64 encoded text of data_content

Example​

string.base64_encode
-- Base64 encode the png format data of a screen area
b64s = screen.image(0, 0, 100, 100):png_data():base64_encode()

-- Read file data and base64 encode it
b64s = file.reads('/var/mobile/1.png'):base64_encode()

Encrypt and Decrypt Strings (string.aes128_encrypt,decrypt)​

Declaration​

encrypted_data = string.aes128_encrypt(data_content, key)  -- Encrypt
data_content = string.aes128_decrypt(encrypted_data, key)  -- Decrypt

Parameters and Return Values​

  • data_content string
  • key string
  • encrypted_data string

Description​

  • string.aes128_encrypt uses the AES128 algorithm in ECB mode to encrypt the original data_content into encrypted_data.
  • string.aes128_decrypt uses the AES128 algorithm in ECB mode to decrypt encrypted_data back to the original data_content.
note

The AES128 algorithm in ECB mode does not have an iv (initialization vector) parameter. If it is required in development, it should be 0.

Example​

string.crypto
local msg = "\5\4\3\2\1\0"
local key = "sozereal"
local emsg = msg:aes128_encrypt(key)
local emsgb64 = emsg:base64_encode()
sys.alert('Binary data <'..msg:to_hex()..'> \n Encrypted using AES128 algorithm with key "'..key..'" is: <'..emsg:to_hex()..'> \n Base64 string is "'..emsgb64..'"')
local tmp = emsgb64:base64_decode()
msg = tmp:aes128_decrypt(key)
sys.alert('The data after base64 decoding "'..emsgb64..'" is <'..tmp:to_hex()..'> \n Decrypted using AES128 algorithm with key "'..key..'" is: <'..msg:to_hex()..'>')

🔤 Split a Text Using a Delimiter (string.split)​

Declaration​

split_text_array = string.split(text_to_split, delimiter[, max_return_count])

Parameters and Return Values​

  • text_to_split text
  • delimiter text
  • max_return_count
    • integer, optional, split results exceeding this count will be discarded
  • split_text_array
    • list of texts, the split text fragments are arranged in order in this table

Example 1​

string.split
t = string.split('lfue6841214----123456', '----')
sys.alert('Account is: '..t[1])

Example 2​

string.split
t = string.split('Hello, the verification code is #4937#, valid for 15 minutes. [Explosive Technology]', '#')
sys.alert('Verification code is: '..t[2])

Example 3​

string.split
t = string.split('Hello, the verification code is 4937, valid for 15 minutes. [Explosive Technology]', 'Verification code is')
t = string.split(t[2], ', valid for 15 minutes')
sys.alert('Verification code is: '..t[1])

Example 4​

string.split
assert(#string.split(multi_line, "\n") == 8)
assert(#string.split(multi_line, "hello") == 9)
assert(#string.split(multi_line, "\n", 4) == 4)
assert(string.split(multi_line, "HELLO", 4)[1] == multi_line)
assert(string.split(multi_line, "\n", 1)[1] == "hello001")
assert(string.split("", "\n")[1] == "")

Encapsulation Example 1​

string.split
-- Encapsulation to get the middle part of the text (returns nil if no match is found)
function str_middle(str, sep1, sep2)
  assert(type(str) == 'string', '`str_middle` parameter #1 must be a string')
  assert(type(sep1) == 'string', '`str_middle` parameter #2 must be a string')
  assert(type(sep2) == 'nil' or type(sep2) == 'string', '`str_middle` parameter #3 is optional but must be a string')
  local t = string.split(str, sep1)
  if not sep2 or sep1 == sep2 then
    return t[2]
  else
    if t[2] == nil then
      return nil
    else
      t = string.split(t[2], sep2)
      if t[2] == nil then
        return nil
      else
        return t[1]
      end
    end
  end
end
-- The above encapsulation can be copied to the script for use
--
r = str_middle('Hello, the verification code is 4937, valid for 15 minutes. [Explosive Technology]', 'code is', ', valid for 15 minutes')
sys.alert('Verification code is: '..r)
-- Output: "Verification code is: 4937"
--
r = str_middle('Hello, the verification code is #8346#, valid for 15 minutes. [Explosive Technology]', '#')
sys.alert('Verification code is: '..r)
-- Output: "Verification code is: 8346"

Encapsulation Example 2​

string.split
-- Get the file name from the absolute path
function str_strip_dirname(path)
  local d = string.split(path, '/')
  return d[#d]
end
-- Get the directory from the absolute path
function str_strip_filename(path)
  local d = string.split(path, '/')
  d[#d] = nil
  return table.concat(d, '/')
end
-- Remove the extension (suffix) from the last part of the path
function str_strip_extension(path)
  local d = string.split(path, '/')
  local fnt = string.split(d[#d], '.')
  d[#d] = fnt[1]
  return table.concat(d, '/')
end
-- Get the extension (suffix) from the last part of the path
function str_get_extension(path)
  local d = string.split(path, '/')
  local fnt = string.split(d[#d], '.')
  table.remove(fnt, 1)
  return table.concat(fnt, '.')
end
--
sys.alert(str_strip_dirname("/private/var/mobile/Media/1ferver/lua/scripts/1.lua.xxt"))
-- Output: "1.lua.xxt"
sys.alert(str_strip_filename("/private/var/mobile/Media/1ferver/lua/scripts/1.lua.xxt"))
-- Output: "/private/var/mobile/Media/1ferver/lua/scripts"
sys.alert(str_strip_extension("/private/var/mobile/Media/1ferver/lua/scripts/1.lua.xxt"))
-- Output: "/private/var/mobile/Media/1ferver/lua/scripts/1"
sys.alert(str_get_extension("/private/var/mobile/Media/1ferver/lua/scripts/1.lua.xxt"))
-- Output: "lua.xxt"
sys.alert(str_strip_extension(str_strip_dirname("/private/var/mobile/Media/1ferver/lua/scripts/1.lua.xxt")))
-- Output: "1"

Related Example: Split Text Character by Character​

string.explode
-- This is not an example using string.split
-- Explode mixed Chinese and English text into individual characters, only supports UTF-8 encoded text
function string.explode(text)
  local ret = {}
  for p, c in utf8.codes(text) do
    ret[#ret + 1] = utf8.char(c)
  end
  return ret
end
--
local t = string.explode('Hello, XXTouch')
sys.alert(table.concat(t, '/'))
-- Output: "H/e/l/l/o/,/ /X/X/T/o/u/c/h"

🔤 Remove Whitespace Characters from Text (string.ltrim,rtrim,trim,atrim)​

Declaration​

processed_text = string.ltrim(original_text)  -- Remove whitespace characters from the left side of the text
processed_text = string.rtrim(original_text)  -- Remove whitespace characters from the right side of the text
processed_text = string.trim(original_text)   -- Remove whitespace characters from both sides of the text
processed_text = string.atrim(original_text)  -- Remove all whitespace characters from the text

Parameters and Return Values​

  • original_text text
  • processed_text text
note

Whitespace characters include "\r" "\n" "\t" etc.

Example​

string.trim
assert(string.trim("  sp a ces  ") == "sp a ces")
assert(string.ltrim("  sp a ces  ") == "sp a ces  ")
assert(string.rtrim("  sp a ces  ") == "  sp a ces")
assert(string.atrim("  sp a ces  ") == "spaces")
string.utils
str = "  Haha,he he,1,3,6  "
new = str:split(",")    -- Split the string str by `,` and return a table
sys.alert(new[2])
sys.alert(str:rtrim())  -- Result: "  Haha,he he,1,3,6", remove whitespace characters from the end of the string
sys.alert(str:ltrim())  -- Result: "Haha,he he,1,3,6  ", remove whitespace characters from the beginning of the string
sys.alert(str:trim())   -- Result: "Haha,he he,1,3,6", remove whitespace characters from both ends of the string
sys.alert(str:atrim())  -- Result: "Haha,hehe,1,3,6", remove all whitespace characters from the string

🔤 Left and Right Padding (string.lpad,rpad)​

Declaration​

processed_text = string.lpad(original_text, pad_length, [pad_text = " "])  -- Left padding
processed_text = string.rpad(original_text, pad_length, [pad_text = " "])  -- Right padding

Parameters and Return Values​

  • original_text text
  • pad_length integer
  • pad_text
    • text, optional, the text used to pad original_text to pad_length
  • processed_text text

Description​

  • Repeatedly pad original_text with pad_text on the left or right until the text length reaches or exceeds pad_length.
  • If the last padding exceeds pad_length, the pad_text used for padding will be truncated to make the final text length exactly equal to pad_length.
  • If pad_length is less than original_text, nothing will happen. The length of processed_text is always greater than or equal to the length of original_text.

Example​

string.lpad
assert(string.lpad("text_message", 16) == "    text_message")
assert(string.lpad("text_message", 8) == "text_message")
assert(string.lpad("text_message", 20, "0") == "00000000text_message")
assert(string.lpad("text_message", 20, "0ab") == "0ab0ab0atext_message")  -- Exceeds pad length, truncates pad text
assert(string.lpad("text", 6, "longmessage") == "lotext")

local _, err = pcall(function ()
  string.lpad("text_message", -7)
end)
assert(err)
string.rpad
assert(string.rpad("text_message", 16) == "text_message    ")
assert(string.rpad("text_message", 8) == "text_message")
assert(string.rpad("text_message", 20, "0") == "text_message00000000")
assert(string.rpad("text_message", 20, "0ab") == "text_message0ab0ab0a")  -- Exceeds pad length, truncates pad text
assert(string.rpad("text", 6, "longmessage") == "textlo")

local _, err = pcall(function ()
  string.rpad("text_message", -7)
end)
assert(err)

🔤 Remove UTF8-BOM from Text (string.strip_utf8_bom)​

Declaration​

processed_text = string.strip_utf8_bom(original_text)

Parameters and Return Values​

  • original_text text
  • processed_text text
note

The UTF-8-BOM appears as three invisible characters "\xEF\xBB\xBF" at the beginning of the document.
BOM (Byte Order Mark) is prepared for UTF-16 and UTF-32 to mark the byte order. Microsoft uses BOM in UTF-8 to clearly distinguish UTF-8 from ASCII and other encodings, but such files can cause problems on non-Windows operating systems.
UTF-8 does not need BOM, although the Unicode standard allows BOM in UTF-8. Placing BOM in UTF-8 files is a Microsoft habit (calling little-endian UTF-16 with BOM "Unicode" without further explanation is also a Microsoft habit).

Example​

string.strip_utf8_bom
txt = "\xEF\xBB\xBFXXTouch"
sys.alert(txt..', '..#txt) -- Output: "XXTouch, 10"
--
txt = string.strip_utf8_bom(txt)
sys.alert(txt..', '..#txt) -- Output: "XXTouch, 7"

🔤 Generate Random Text (string.random)​

Declaration​

random_text = string.random(character_pool[, character_count])

Parameters and Return Values​

  • character_pool
    • text, the dictionary for generating text
  • character_count
    • integer, optional, the number of characters to generate in the random text, default is 6
  • random_text
    • text, returns the generated random text

Example​

string.random
rs = string.random("qwertyuiopasdfghjklzxcvbnm", 20)
rs = string.random("一二三四五六七八九十", 20)

🔤 Text Comparison (string.compare/string.localized_compare)​

Declaration​

comparison_result = string.compare(text1, text2[, case_sensitive])  -- Dictionary order comparison
comparison_result = string.localized_compare(text1, text2)        -- Comparison based on the standard sorting rules set by the operating system and locale

Parameters and Return Values​

  • text1, text2
    • text, the two texts to compare
  • case_sensitive
    • boolean, optional, whether to distinguish between uppercase and lowercase, default is false
  • comparison_result
    • integer, text1 greater than text2 returns 1, text1 less than text2 returns -1, texts are equal returns 0

Description​

  • string.compare compares in dictionary order
  • string.localized_compare compares based on the standard sorting rules set by the operating system and locale

Example​

string.compare
assert(string.compare("test1.luaBB", "test2.luaAA") == -1)
assert(string.compare("test3.luaDD", "test2.luaGG") == 1)
assert(string.compare("1.2-2", "1.2-10") == 1)
assert(string.compare("AaBbCcDd", "AAbbCCdd", true) == 0)
assert(string.compare("AaBbCcDd", "AAbbCCdd", false) == 1)
assert(string.compare("test.lua", "test.lua") == 0)
assert(string.compare("", "") == 0)

🔤 Compare Two Version Numbers (string.compare_version)​

Declaration​

comparison_result = string.compare_version(version1, version2)

Parameters and Return Values​

  • version1, version2
    • text, the two version numbers to compare
  • comparison_result
    • integer, version1 greater than version2 returns 1, version1 less than version2 returns -1, version numbers are equal returns 0

Description​

Compares the size of two version number strings, following the comparison rules below:

  • Pure numeric values separated by dots . or hyphens - or spaces
  • Different separators have the same effect, multiple separators together are considered as one separator
  • The weight decreases gradually from left to right
  • Any illegal characters encountered will truncate and not compare the following content
  • If the number of segments is not equal, the missing segments are compared with 0
  • Empty strings or illegal strings are considered as version number "0"
note
  • '1.1' and '1.1.0' are equal version numbers
  • '1.1' and '1.1-0' are equal version numbers
  • '1.1' and '1-1' are equal version numbers
  • '1.0' and '1 0' are equal version numbers
  • '1.0' is greater than '0.99999'

Example​

string.compare_version
assert(string.compare_version("", "") == 0)
assert(string.compare_version("1", "") == 1)
assert(string.compare_version("", "1") == -1)
assert(string.compare_version("1", "1") == 0)
assert(string.compare_version("1.0", "1") == 0)
assert(string.compare_version("1", "1.0") == 0)
assert(string.compare_version("1.", "1") == 0)
assert(string.compare_version("1", "1.") == 0)
assert(string.compare_version("1.", "1.0") == 0)
assert(string.compare_version("1.0", "1.") == 0)
assert(string.compare_version("1.0", "1.0") == 0)
assert(string.compare_version("1.0.0", "1.0.0") == 0)
assert(string.compare_version("1.1", "1.0") == 1)
assert(string.compare_version("1.0", "1.1") == -1)
assert(string.compare_version("1.1", "1.10") == -1)
assert(string.compare_version("1.2", "1.11") == -1)
assert(string.compare_version("1.1", "1.1.1") == -1)
assert(string.compare_version("1.2", "1.1.1") == 1)
assert(string.compare_version("1.0", "0.99999") == 1)
assert(string.compare_version("1.10.1", "1.10") == 1)
assert(string.compare_version("1.2-4", "1.2-3") == 1)
assert(string.compare_version("1.2-3", "1.2.3") == 0)
assert(string.compare_version("1.2-4", "1.2.3.0") == 1)
assert(string.compare_version("1.2-4", "1.2.3.10") == 1)
assert(string.compare_version("1.2-4", "1.2.30.10") == -1)
assert(string.compare_version("1.2-3", "1.2.4") == -1)
assert(string.compare_version("2.2", "1.2") == 1)
assert(string.compare_version("2.2", "10.2") == -1)
assert(string.compare_version("2..2", "2.2") == 0)
assert(string.compare_version("2.2.x.3", "2.2") == 0)
assert(string.compare_version("x", "") == 0)

🔤 URL Encoding (string.encode_uri/string.encode_uri_component)​

Declaration​

encoded_text = string.encode_uri(text_to_encode)            -- Encode the entire URL/URI
encoded_text = string.encode_uri_component(text_to_encode)  -- Encode the components of the URL/URI

Parameters and Return Values​

  • text_to_encode text
  • encoded_text text

Description​

Encodes certain characters in the URL/URI as % prefixed text.

  • string.encode_uri encodes the character range including
    • ;,/?:@&=+$# Reserved Characters
    • -_.!~*'() Unreserved Marks
  • string.encode_uri_component encodes the character range including
    • -_.!~*'() Unreserved Marks

🔤 URL Decoding (string.decode_uri)​

Declaration​

decoded_text = string.decode_uri(text_to_decode)

Parameters and Return Values​

  • text_to_decode text
  • decoded_text text

Description​

Removes % prefixed text and converts it back to its pre-encoded text.

note

🔤 Convert Halfwidth to Fullwidth (string.to_fullwidth)​

Declaration​

fullwidth_text = string.to_fullwidth(halfwidth_text)

Parameters and Return Values​

  • halfwidth_text text
  • fullwidth_text text

Description​

Converts halfwidth text to fullwidth text, e.g., "a" to "ａ", "1" to "１", etc.

note

This function is the inverse of string.to_halfwidth.

Example​

string.to_fullwidth
assert(string.to_fullwidth(",.?123abc") == "，．？１２３ａｂｃ")
assert(string.to_fullwidth(",.?123abc汉字") == "，．？１２３ａｂｃ汉字")
assert(string.to_fullwidth("") == "")

🔤 Convert Fullwidth to Halfwidth (string.to_halfwidth)​

Declaration​

halfwidth_text = string.to_halfwidth(fullwidth_text)

Parameters and Return Values​

  • fullwidth_text text
  • halfwidth_text text

Description​

Converts fullwidth text to halfwidth text, e.g., "ａ" to "a", "１" to "1", etc.

note

This function is the inverse of string.to_fullwidth.

Example​

string.to_halfwidth
assert(string.to_halfwidth("，．？１２３ａｂｃ") == ",.?123abc")
assert(string.to_halfwidth("，．？１２３ａｂｃ汉字") == ",.?123abc汉字")
assert(string.to_halfwidth("") == "")

🔤 Capitalize First Letter (string.to_capitalized)​

Declaration​

capitalized_text = string.to_capitalized(text)

Parameters and Return Values​

  • text text
  • capitalized_text text

Description​

Converts the first letter of the text to uppercase, while keeping the rest of the letters unchanged. For example, "hello" becomes "Hello", "HELLO" remains "HELLO", "123" remains "123", etc.

Example​

string.to_capitalized
assert(string.to_capitalized("good night my baby boy") == "Good Night My Baby Boy")
assert(string.to_capitalized("Do you like 中文 2333?") == "Do You Like 中文 2333?")
assert(string.to_capitalized("") == "")

🔤 Convert to Pinyin Text (string.to_pinyin)​

Declaration​

pinyin_text = string.to_pinyin(text, [remove_tone])

Parameters and Return Values​

  • text text
  • remove_tone boolean
  • pinyin_text text

Description​

Converts text to pinyin text. For example, 你好 becomes "nǐ hǎo".
If remove_tone is true, the tone is removed. For example, 你好 becomes "ni hao".

Example​

string.to_pinyin
assert(string.to_pinyin("你好, zhe shi 中文！") == "nǐ hǎo, zhe shi zhōng wén！")
assert(string.to_pinyin("你好, zhe shi 中文！", true) == "ni hao, zhe shi zhong wen！")
assert(string.to_pinyin("") == "")

🔤 Is Numeric Form (string.is_number)​

Declaration​

result = string.is_number(text)

Parameters and Return Values​

  • text text
  • result boolean

Description​

Determines whether the text is in numeric form, such as "123", "123.456", "1.2e3", etc.

note

string.is_numeric only determines whether the text consists solely of digits 0 ~ 9, while this function string.is_number determines whether the text is in numeric form.

Example​

string.is_number
assert(string.is_number('1234567890'))
assert(string.is_number('12345678.90'))
assert(string.is_number('1.2e3'))
assert(string.is_number('') == false)
assert(string.is_number('123abc') == false)
assert(string.is_number('123abc7890') == false)

🔤 Is Integer Form (string.is_integer)​

Declaration​

result = string.is_integer(text)

Parameters and Return Values​

  • text text
  • result boolean

Description​

Determines whether the text is in integer form, such as "123", "-123", etc.

note

string.is_numeric only determines whether the text consists solely of digits 0 ~ 9, while this function string.is_integer determines whether the text is in integer form.

Example​

string.is_integer
assert(string.is_integer('1234567890'))
assert(string.is_integer('-1234567890'))
assert(string.is_integer('') == false)
assert(string.is_integer('123abc') == false)
assert(string.is_integer('123abc7890') == false)

🔤 Is Email Address (string.is_email)​

Declaration​

result = string.is_email(text)

Parameters and Return Values​

  • text text
  • result boolean

Description​

Determines whether the text is an email address using the regular expression "[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}".
Empty text returns false.

Example​

string.is_email
assert(string.is_email('123abc7890') == false)
assert(string.is_email('') == false)
assert(string.is_email('http://www.baidu.com') == false)
assert(string.is_email('bug@xxtou.ch'))
assert(string.is_email('i.82@me.com'))
assert(string.is_email('darwindev@mail.me.com'))

🔤 Is Link Address (string.is_link)​

Declaration​

result = string.is_link(text)

Parameters and Return Values​

  • text text
  • result boolean

Description​

Determines whether the text is a link address using the regular expression "https?://[%w%.%-/:]+".
Empty text returns false.

Example​

string.is_link
assert(string.is_link('123abc7890') == false)
assert(string.is_link('') == false)
assert(string.is_link('http://www.baidu.com'))
assert(string.is_link('bug@xxtou.ch') == false)
assert(string.is_link('http://iphonedevwiki.net/index.php/Preferences_specifier_plist#PSEditTextCell_.26_PSSecureEditTextCell'))
assert(string.is_link('https://www.baidu.com/link?url=x_ZHKOUxi0VTwAXF4CFR8t2zW2qtph1p6SM1LsAgjcRyHFXnCQaCnYqmstyTWpBhRzs_00TZLwVrju24jGMEG_&wd=&eqid=8a23ea0b0003da8f000000045b1bae78'))
assert(string.is_link('https://82flex.com/2018/04/12/difference-between-UTF8String-and-fileSystemRepresentation.html'))

🔤 Is Alphabetic or Numeric (string.is_letter,upper,lower,numeric,alphanumeric)​

Declaration​

result = string.is_letter(text)        -- Is it all letters
result = string.is_upper(text)         -- Is it all uppercase letters
result = string.is_lower(text)         -- Is it all lowercase letters
result = string.is_numeric(text)       -- Is it all digits
result = string.is_alphanumeric(text)  -- Is it all letters or digits

Parameters and Return Values​

  • text text
  • result boolean

Description​

Determines whether the text contains only uppercase and lowercase letters [A-Za-z] or digits [0-9], or a combination of both.
Empty text returns false.

Example​

string.is_letter
assert(string.is_letter('abcDEFGHijk'))
assert(string.is_letter('') == false)
assert(string.is_letter('123aBc') == false)
assert(string.is_letter('123aBc7890') == false)
string.is_upper
assert(string.is_upper('ABCDEFGHIJK'))
assert(string.is_upper('') == false)
assert(string.is_upper('abcdefghijk') == false)
assert(string.is_upper('123ABC') == false)
assert(string.is_upper('123abc7890') == false)
string.is_lower
assert(string.is_lower('ABCDEFGHIJK') == false)
assert(string.is_lower('') == false)
assert(string.is_lower('abcdefghijk'))
assert(string.is_lower('123ABC') == false)
assert(string.is_lower('123abc7890') == false)
string.is_numeric
assert(string.is_numeric('1234567890'))
assert(string.is_numeric('12345.67890') == false)
assert(string.is_numeric('') == false)
assert(string.is_numeric('123abc') == false)
assert(string.is_numeric('123abc7890') == false)

🔤 Is Chinese (string.is_chinese)​

Declaration​

result = string.is_chinese(text)

Parameters and Return Values​

  • text text
  • result boolean

Description​

Determines whether the first character of the UTF-8 text is Chinese.
Empty text returns false.

Example​

string.is_chinese
assert(string.is_chinese("是汉字吗"))
assert(string.is_chinese("是 Chinese Character 吗"))
assert(string.is_chinese("is 汉字吗") == false)
assert(string.is_chinese("Chinese Character") == false)
assert(string.is_chinese("") == false)