String Manipulation Functions – library MetaTrader 5

A collection of useful string manipulation functions

Function	Description
StringAppendIfMissing()	Appends the suffix to the end of the string if the string does not already end with the suffix.
StringCharAt()	Returns the character at the specified index in a string.
StringCharCodeAt()	Returns a short integer between 0 and 65535 representing the UTF-16 code unit at the given index.
StringChunk()	Split a string into evenly sized chunks of the specified length.
StringChunkRight()	Split a string into evenly sized chunks of the specified length, starting the split at the end of the string.
StringContains()	Determines whether this string contains the specified substring.
StringCountMatches()	Counts the number of all occurrences of the specified string in the input string using case-sensitive search.
StringEndsWith()	Determines whether this string ends with the specified suffix.
StringGenerateRandom()	Generates a random string with a desired length from ascii characters.
StringIndexOf()	Returns the index within this string of the first occurrence of the specified substring, starting the search at the specified index.
StringInsert()	Returns a new string in which a specified substring is inserted at a specified index position in this string.
StringIsNullOrEmpty()	Indicates whether the specified string is NULL or an empty string (“”).
StringIsNumeric()	Determines whether the input string consists only of decimal digits.
StringJoin()	Returns the result string, formed by joining of string parameters using a specified separator.
StringLastIndexOf()	Returns the index within this string of the last occurrence of the specified substring, searching backward starting at the specified index.
StringLeft()	Extracts the leftmost ‘length’ characters of a string.
StringPad()	Returns a new string of a specified length in which the input string is centered by padding with a specified character.
StringPadEnd()	Returns a new string of a specified length in which the end of the input string is padded with a specified character.
StringPadStart()	Returns a new string of a specified length in which the beginning of the input string is padded with a specified character.
StringPrependIfMissing()	Prepends the prefix to the start of the string if the string does not already start with the prefix.
StringRemove()	Returns a new string in which all occurrences of a specified string in the input string are removed.
StringRemoveEnd()	Removes the specified suffix from the end of the string if the string already ends with the suffix.
StringRemoveStart()	Removes the specified prefix from the start of the string if the string already starts with the prefix.
StringRepeat()	Returns a new string which contains the specified number of copies of the input string, concatenated together.
StringReplace2()	Returns a new string in which all occurrences of a specified string in the input string are replaced with another specified string.
StringReplaceBetween()	Replaces the string that is nested in between two string tags. Only the first match is replaced.
StringReverse()	Returns a copy of this string with all the characters reversed.
StringRight()	Extracts the rightmost ‘length’ characters of a string.
StringShuffle()	Returns a copy of this string with all the characters shuffled.
StringSplit()	Overload for string separator. Split a string into an array of substrings, using a specified separator string.
StringSplitTrim()	As StringSplit + Substrings that consist only of white-space characters are removed from the result.
StringStartsWith()	Determines whether this string starts with the specified prefix.
StringSubstrAfter()	Gets the substring after the first occurrence of a separator. The separator is not returned.
StringSubstrAfterLast()	Gets the substring after the last occurrence of a separator. The separator is not returned.
StringSubstrBefore()	Gets the substring before the first occurrence of a separator. The separator is not returned.
StringSubstrBeforeLast()	Gets the substring before the last occurrence of a separator. The separator is not returned.
StringSubstrBetween()	Gets the string that is nested in between two string tags. Only the first match is returned.
StringToLowerCase()	Returns a copy of this string converted to lowercase.
StringToUpperCase()	Returns a copy of this string converted to uppercase.
StringTrim()	Returns a new string in which all leading and trailing white-space characters found in the input string are removed.
StringTrimEnd()	Returns a new string in which all trailing white-space characters found in the input string are removed.
StringTrimStart()	Returns a new string in which all leading white-space characters found in the input string are removed.
DQuoteStr()	Returns a copy of this string enclosed in a pair of double quotes. This helps to pass string parameters on the command-line.
StrHashCode()	Generates 32 bit FNV-1a hash value from the given string.
Base64Encode()	Encodes a string using Base64 encoding scheme.
Base64Decode()	Decodes a Base64-encoded string into the original string.
UTF8GetBytes()	Encodes this string into a sequence of bytes using UTF-8 encoding. This helps to send string messages via web sockets.
UTF8GetString()	Decodes a sequence of bytes into a string using UTF-8 encoding.
UnicodeGetBytes()	Encodes this string into a sequence of bytes using Unicode (UTF16) encoding. This helps to pass string parameters to Windows api functions.
UnicodeGetString()	Decodes a sequence of bytes into a string using Unicode (UTF16) encoding.

Immuable strings:

The source string is not modified (i.e., immutable).

Demo

//+------------------------------------------------------------------+
//|                                                 StringUtils_demo |
//|                                        Copyright © 2018, Amr Ali |
//|                             https://www.mql5.com/en/users/amrali |
//+------------------------------------------------------------------+
#property copyright "Copyright © 2018, Amr Ali"
#property link      "https://www.mql5.com/en/users/amrali"
#property version   "1.800"
#property description "A collection of string manipulation functions."

#include <StringUtils.mqh>
//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
#define PRINT(A) PrintHelper(#A, (A))

//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
template<typename T>
void PrintHelper(string _A, const T A)
  {
   if(typename(T) == "string")
      Print(_A + " = ", """ + (string)A + """);
   else
      Print(_A + " = ", (string)A);
  }
//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
void OnStart()
  {
   /**
    * All functions return a modified copy of the input string.
    * The source string is not modified (i.e., immutable).
    */
   PRINT( StringAppendIfMissing("dir", "\") );
   PRINT( StringAppendIfMissing("dir\", "\") );
   PRINT( StringCharAt("Apple", 4) );
   PRINT( StringCharCodeAt("Apple", 4) );
   string parts[];
   PRINT( StringChunk("1234567890", 3, parts) );
   ArrayPrint(parts);
   PRINT( StringChunkRight("1234567890", 3, parts) );
   ArrayPrint(parts);
   PRINT( StringContains("life_is_good", "is") );
   PRINT( StringCountMatches("Mr Blue has a blue house and a blue car", "blue") );
   PRINT( StringEndsWith("life_is_good", "good") );
   PRINT( StringEndsWith("life_is_good", "is", 7) );
   PRINT( StringGenerateRandom(12) );
   PRINT( StringIndexOf("Morning", "n") );
   PRINT( StringInsert("012345", "xxx", 3) );
   PRINT( StringIsNullOrEmpty(NULL) );
   PRINT( StringIsNullOrEmpty("") );
   PRINT( StringIsNumeric("12345") );
   PRINT( StringIsNumeric("3.142") );
   PRINT( StringJoin("-", "Java", "is", "cool") );
   PRINT( StringLastIndexOf("Morning", "n") );
   PRINT( StringLeft("helicopter") );
   PRINT( StringLeft("vehicle", 2) );
   PRINT( StringLeft("car", 5) );
   PRINT( StringPad("MQL5 is awesome", 21, '*') );
   PRINT( StringPadEnd("USD", 5) );
   PRINT( StringPadEnd("1.3", 5, '0') );
   PRINT( StringPadStart("USD", 5) );
   PRINT( StringPadStart("123", 5, '0') );
   PRINT( StringPrependIfMissing("domain.com", "www.") );
   PRINT( StringPrependIfMissing("www.domain.com", "www.") );
   PRINT( StringRemove("Mr Blue has a blue house and a blue car", "blue ") );
   PRINT( StringRemoveEnd("www.domain.com", ".com") );
   PRINT( StringRemoveStart("www.domain.com", "www.") );
   PRINT( StringRemoveStart("domain.com", "www.") );
   PRINT( StringRepeat("*", 5) );
   PRINT( StringRepeat('*', 5) );
   PRINT( StringReplace2("Mr Blue has a blue house and a blue car", "blue", "red") );
   PRINT( StringReplaceBetween("<a>foo</a>", "<a>", "</a>", "bar") );
   PRINT( StringReverse("012345") );
   PRINT( StringRight("helicopter") );
   PRINT( StringRight("vehicle", 2) );
   PRINT( StringRight("car", 5) );
   PRINT( StringShuffle("012345") );
   PRINT( StringSplit("_life_is_good_", "_", parts) );
   ArrayPrint(parts);
   PRINT( StringSplitTrim("_life_is_good_", "_", parts) );
   ArrayPrint(parts);
   PRINT( StringStartsWith("life_is_good", "life") );
   PRINT( StringStartsWith("life_is_good", "is", 5) );
   PRINT( StringSubstrAfter("abcba", "b") );
   PRINT( StringSubstrAfterLast("abcba", "b") );
   PRINT( StringSubstrBefore("abcba", "b") );
   PRINT( StringSubstrBeforeLast("abcba", "b") );
   PRINT( StringSubstrBetween("<a>foo</a>", "<a>", "</a>") );
   PRINT( StringToLowerCase("MetaTrader 5") );
   PRINT( StringToUpperCase("MetaTrader 5") );
   PRINT( StringTrim("  Hello World!  ") );
   PRINT( StringTrimEnd("  Hello World!  ") );
   PRINT( StringTrimStart("  Hello World!  ") );
   PRINT( DQuoteStr(MQLInfoString(MQL_PROGRAM_PATH)) );
   PRINT( StrHashCode("https://twitter.com/") );
   PRINT( StrHashCode("Привет мир!") );
   const long magicNumber = ((long) StrHashCode("MyExpertName") << 31) + StrHashCode(_Symbol);
   PRINT( magicNumber );
   PRINT( Base64Encode("https://twitter.com/") );
   PRINT( Base64Decode("aHR0cHM6Ly90d2l0dGVyLmNvbS8=") );
   PRINT( Base64Encode("Привет мир!") );
   PRINT( Base64Decode("0J/RgNC40LLQtdGCINC80LjRgCE=") );
   uchar bytes[];
   PRINT( UTF8GetBytes("MQL5", bytes) );
   ArrayPrint(bytes);
   PRINT( UTF8GetString(bytes) );
   ushort chars[];
   PRINT( UnicodeGetBytes("MQL5", chars) );
   ArrayPrint(chars);
   PRINT( UnicodeGetString(chars) );
  }
//+------------------------------------------------------------------+

// Expected output:
/*
  StringAppendIfMissing(dir,) = "dir"
  StringAppendIfMissing(dir,) = "dir"
  StringCharAt(Apple,4) = "e"
  StringCharCodeAt(Apple,4) = 101
  StringChunk(1234567890,3,parts) = 4
  "123" "456" "789" "0"
  StringChunkRight(1234567890,3,parts) = 4
  "890" "567" "234" "1"
  StringContains(life_is_good,is) = true
  StringCountMatches(Mr Blue has a blue house and a blue car,blue) = 2
  StringEndsWith(life_is_good,good) = true
  StringEndsWith(life_is_good,is,7) = true
  StringGenerateRandom(12) = "9VPP7jZcShNz"
  StringIndexOf(Morning,n) = 3
  StringInsert(012345,xxx,3) = "012xxx345"
  StringIsNullOrEmpty(NULL) = true
  StringIsNullOrEmpty() = true
  StringIsNumeric(12345) = true
  StringIsNumeric(3.142) = true
  StringJoin(-,Java,is,cool) = "Java-is-cool"
  StringLastIndexOf(Morning,n) = 5
  StringLeft(helicopter) = "h"
  StringLeft(vehicle,2) = "ve"
  StringLeft(car,5) = "car"
  StringPad(MQL5 is awesome,21,'*') = "***MQL5 is awesome***"
  StringPadEnd(USD,5) = "USD  "
  StringPadEnd(1.3,5,'0') = "1.300"
  StringPadStart(USD,5) = "  USD"
  StringPadStart(123,5,'0') = "00123"
  StringPrependIfMissing(domain.com,www.) = "www.domain.com"
  StringPrependIfMissing(www.domain.com,www.) = "www.domain.com"
  StringRemove(Mr Blue has a blue house and a blue car,blue ) = "Mr Blue has a house and a car"
  StringRemoveEnd(www.domain.com,.com) = "www.domain"
  StringRemoveStart(www.domain.com,www.) = "domain.com"
  StringRemoveStart(domain.com,www.) = "domain.com"
  StringRepeat(*,5) = "*****"
  StringRepeat('*',5) = "*****"
  StringReplace2(Mr Blue has a blue house and a blue car,blue,red) = "Mr Blue has a red house and a red car"
  StringReplaceBetween(<a>foo</a>,<a>,</a>,bar) = "<a>bar</a>"
  StringReverse(012345) = "543210"
  StringRight(helicopter) = "r"
  StringRight(vehicle,2) = "le"
  StringRight(car,5) = "car"
  StringShuffle(012345) = "145230"
  StringSplit(_life_is_good_,_,parts) = 5
  ""     "life" "is"   "good" ""
  StringSplitTrim(_life_is_good_,_,parts) = 3
  "life" "is"   "good"
  StringStartsWith(life_is_good,life) = true
  StringStartsWith(life_is_good,is,5) = true
  StringSubstrAfter(abcba,b) = "cba"
  StringSubstrAfterLast(abcba,b) = "a"
  StringSubstrBefore(abcba,b) = "a"
  StringSubstrBeforeLast(abcba,b) = "abc"
  StringSubstrBetween(<a>foo</a>,<a>,</a>) = "foo"
  StringToLowerCase(MetaTrader 5) = "metatrader 5"
  StringToUpperCase(MetaTrader 5) = "METATRADER 5"
  StringTrim(  Hello World!  ) = "Hello World!"
  StringTrimEnd(  Hello World!  ) = "  Hello World!"
  StringTrimStart(  Hello World!  ) = "Hello World!  "
  DQuoteStr(MQLInfoString(MQL_PROGRAM_PATH)) = ""C:Program FilesMetaTrader 5MQL5ScriptsStringUtils_demo.ex5""
  StrHashCode(https://twitter.com/) = 2363652379
  StrHashCode(Привет мир!) = 3271322339
  magicNumber = 9094825662509768225
  Base64Encode(https://twitter.com/) = "aHR0cHM6Ly90d2l0dGVyLmNvbS8="
  Base64Decode(aHR0cHM6Ly90d2l0dGVyLmNvbS8=) = "https://twitter.com/"
  Base64Encode(Привет мир!) = "0J/RgNC40LLQtdGCINC80LjRgCE="
  Base64Decode(0J/RgNC40LLQtdGCINC80LjRgCE=) = "Привет мир!"
  UTF8GetBytes(MQL5,bytes) = 4
  77 81 76 53
  UTF8GetString(bytes) = "MQL5"
  UnicodeGetBytes(MQL5,chars) = 4
  77 81 76 53
  UnicodeGetString(chars) = "MQL5"
*/