Texas Instruments TI-99/4A - Page 119

Built-In String Functions
Introduction
In addition to the built-in numeric functions, many other functions
are built into TI BASIC, The functions discussed in this section are
called string functions, String functions either use a string in some
way to
produce a numeric result. or the result ot the evaluation 01
the function is a string. As you use your computer. you will find
many ways to use the
string functions described here You can also
define your own
string functions (see "User-Defined Functions')
N ate that any string function with a name that ends with a dollar
sign (e.g, CHR$) always gives a string result and cannot be used
. . .
10 numenc expressIOns.
User's Reference Guide
Il-90