Pursuant to that issue, I’ll show another command line call and its result:<\/p>\n The result: (Possible) explanation of first result:<\/u><\/p>\n In bash<\/strong>, (Possible) explanation of second result:<\/u><\/p>\n (Possible) explanation of third result:<\/u><\/p>\n (Possible) explanation of the fourth result:<\/u><\/p>\n In Perl, Java, and (it appears) bash<\/strong> as well, the backspace While, for the time being, I’d say we’re finished talking about the Java Scanner example, this post has opened up other topics for the future. HIH:)<\/p>\n I used many helpful sources for this post:<\/p>\n Robert’s Perl tutorial<\/a><\/p>\n linuxsig.org bash scripting<\/a><\/p>\n stackoverflow.com<\/a><\/p>\n Kurniawan, Budi. Java 5: A Beginner’s Tutorial<\/em>. 2006: Brainy Software Corp.<\/p>\n
\nIn my previous article<\/a> I reported a surprising finding of how my Java Scanner program reads dollar sign input from the bash<\/strong> command line.<\/p>\njava TryScanner $0.45 $125.27 $$1.28 \\$56.39<\/code><\/p>\n
\n
\nNot a readable number: bash.45
\nReadable number: 25.27
\nReadable number:22821.28
\nNot a readable number: $56.39
\n<\/code><\/p>\n$0 <\/code>is the command to tell what shell you are using (ie, bash<\/strong>). Bash substitutes bash<\/strong> for $0<\/code> in $0.45<\/code>, giving bash.45<\/code>. TryScanner<\/code> then reads bash.45<\/code> and deems it not a readable number, since it contains non-numeric characters.<\/p>\n$1<\/code>, in bash<\/strong>, means the first command line argument given to a bash<\/strong> script. Since java TryScanner<\/code> isn’t a bash<\/strong> script, $1<\/code> points to a blank value. Therefore, in place of $1<\/code>, bash<\/strong> substitutes a blank. The blank is just whitespace, so it doesn’t pollute the remaining 25.27<\/code>, which TryScanner<\/code> finds and reports as a readable number.<\/p>\n$$<\/code>, in bash<\/strong>, is the command to get the process id (pid) of the terminal. In this case, it’s obviously 2282<\/code>, which is substituted (by bash<\/strong>) in front of 1.28<\/code>. The resulting number 22821.28<\/code> is read and reported by TryScanner<\/code> as a readable number.<\/p>\n\\<\/code> can be used to “escape” other characters. When you escape a character, you change its meaning. We know that the dollar sign $<\/code> has special meaning in bash<\/strong>; apparently the \\<\/code> in front changes it to just a regular character. Bash<\/strong> hands $56.39<\/code> to TryScanner<\/code>, which, seeing the dollar sign in front, deems $56.39<\/code> not a readable number.<\/p>\n