C#

public String delete (String st, int startIndex, int len); //delete part of a string and return the result

public String copy (String st, int startIndex, int len); //copy a subString from startIndex till len and return the result

public String insert (String st1, String st2, int len); //insert a string to an other

public String concat (String st1, String st2); //concat two strings

public int pos (String st1, String st2, int len); //return the position of specified string in an other specified string

public int countOf (String st1, String st2, int len); //return number of repetitions of an string in an other string

public String intToStr(int value); //make an integer to string

public int strToInt (String value); //make a string to an integer

public String reverse (String value); //return the reversed