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1 True BASIC Language System String Handling Libraries In addition to the strings functions included in True BASIC, additional tools are provided in the library STRLIB.TRC. All of the string functions and subroutines are described below in alphabetical order. The operations provided by these functions and subroutines include: Return sets of string constants ALPHANUM$, CONTROL$, DIGITS$, LETTERS$, LOWER$, PUNCT$, RNDSTR$, UPPER$ Return simple parts of strings LEFT$, MID$, RIGHT$ Return date and time strings: NICEDATE$, NICETIME$, NOW$, SHORTDATE$, TODAY, WEEKDAY, WEEKDAY$ Convert between numeric and other representations of numbers: DOLLARS$, DOLLARVAL, ENGLISHNUM$, EVAL, LVAL, ROMAN$, SUPERVAL Parse a string BREAKUP, EXPLODE, EXPLODEN, NEXTWORD Trim extra spaces INTRIM$, LTRIM$, RTRIM$, TRIM$, JUSTIFY$, NOSPACE$ Format text CENTER$, FILLARRAY, FILLFROM, HEADER$, JUSTIFY$, JUSTIFYARRAY, JUSTIFYFROM, LJUST$, RJUST$ Reverse a string REVERSE$ Find shared or non-shared characters in two strings CHARDIFF$, CHARINT$, CHARS$, CHARUNION$, UNIQ$ Remove or replace characters from strings DELCHAR$, DELMIX$, DELSTR$, KEEPCHAR$, MAPCHAR$, NPLUGCHAR$, NREPCHAR$, PLUGCHAR$, PLUGMIX$, PLUGSTR$, REPCHAR$, REPMIX$, REPSTR$ ALPHANUM$ Function Library: Syntax: Usage: Summary: Details: Example: Exceptions: See also: BREAKUP Subroutine Library: Syntax: Usage: Summary: STRLIB.TRC ALPHANUM$ LET set$ = ALPHANUM$ Returns the set of alphabetic and digit characters. The ALPHANUM$ function returns a string containing the set of characters representing the letters of the alphabet, both uppercase and lowercase, as well as the digits, arranged in ascending order according to their ASCII codes. (For a table of the ASCII codes and their corresponding characters, see Appendix A.) That is, it returns the equivalent of the string constant: “0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz” None. None DIGITS$, LETTERS$, UPPER$, LOWER$, PUNCT$, CONTROL$ STRLIB.TRC CALL BREAKUP (strex, strex, strex) CALL BREAKUP (phrase$, word$, delims$) Returns the next word, as delineated by a delimiter character, from the specified phrase.
String Handling Libraries 2 Details: Example: Exceptions: See also: The BREAKUP subroutine returns the next “word” from the specified “phrase.” A phrase is defined as any series of characters, and a word is defined as any series of characters except those defined as delimiters. When invoking the BREAKUP subroutine, you pass the phrase as phrase$ and the characters to be defined as delimiters as delims$. The subroutine then examines the phrase, looking for the first delimiter character, and returns the characters up to but not including this delimiter as the value of word$. It also updates the value of phrase$ to eliminate the returned word and the delimiter. Note that the BREAKUP subroutine strips any leading and trailing spaces off of the return values of word$ and phrase$. For example, assume you have passed delim$ with a value of “*#;” and phrase$ with a value of “***abc***def**” to the BREAKUP subroutine. The subroutine would return word$ with a value of the null string and phrase$ with a new value of “**abc***def**” since there is no non-delimiter value between the beginning of the phrase and the first delimiter. The process of breaking a phrase into words is often referred to as parsing a phrase. If the value of phrase$ does not contain any delimiters, the BREAKUP subroutine will return the value of phrase$ in word$ and return phrase$ equal to the null string. Note that the BREAKUP subroutine is closely related to, but subtly different from, the NEXTWORD subroutine. The BREAKUP subroutine treats each individual delimiter character as a delimiter in its own right, while the NEXTWORD subroutine treats a series of contiguous delimiter characters as a single delimiter. For some applications you will want to use the BREAKUP subroutine, for others you will want to use the NEXTWORD subroutine. The following program: LIBRARY "StrLib.trc" LET s$ = "Now is the time for all good men" DO CALL BreakUp (s$, word$, " ") IF word$ = "" then EXIT DO PRINT word$, LOOP END produces the following output: all good men Now is the time for None NEXTWORD, EXPLODE, EXPLODEN CENTER$ Function Library: Syntax: Usage: Summary: Details: STRLIB.TRC CENTER$ (strex, numex, strex) LET a$ = CENTER$ (text$, width, back$) Returns a string of the specified length containing the value of text$ center-justified. The CENTER$ function takes the value of text$ and adds characters alternately to the beginning and end of it as necessary to create a string containing width characters with the value of text$ centered within it. The characters added will be determined by repeating the sequence of characters specified by the value of back$. Note that if the value of text$ cannot be perfectly centered within the result, the extra
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