The IsASCII(char) function determines whether char is in the ASCII character set (ASCII code 1 through 127).

If char is in the ASCII character set, then IsASCII returns true. Otherwise, false is returned.

If char is a string that contains more than one character, then all the characters in the string are tested. The command returns true if the condition is true of all characters in the input string. For the empty string, the tested condition is vacuously true.

This procedure is part of the StringTools package, and so it can be used in the form IsASCII(..) only after executing the command with(StringTools).  However, it can always be accessed through the long form of the command by using the form StringTools[IsASCII](..).

All of the StringTools package commands treat strings as (null-terminated) sequences of $8$-bit (ASCII) characters.  Thus, there is no support for multibyte character encodings, such as unicode encodings.

The StringTools[IsASCII] command is thread-safe as of Maple 15.

For more information on thread safety, see index/threadsafe.

$\mathrm{with}\left(\mathrm{StringTools}\right)\:$

$s≔\mathrm{convert}\left(\left[\mathrm{`\$`}\left(1..255\right)\right]\,'\mathrm{bytes}'\right)\:$

$\mathrm{length}\left(s\right)$

$255$

$\mathrm{Select}\left(\mathrm{IsASCII}\,s\right)$