ch9_case_shifting.pl

#!/usr/bin/perl -w
use strict;

# \U replaces matched pattern with all Upper Case
$_ = "I saw Fred with Barney.";
print "\$_ = '$_'\n";
print 'Substitution Pattern =  s/(fred|barney)/\U$1/gi',"\n";
s/(fred|barney)/\U$1/gi;
print "\$_ = '$_'\n";

print "-" x 50, "\n";

# \L replaces matched pattern with all Lower Case
$_ = "I saw Fred with Barney.";
print "\$_ = '$_'\n";
print 'Substitution Pattern =  s/(fred|barney)/\L$1/gi',"\n";
s/(fred|barney)/\L$1/gi;

print "\$_ = '$_'\n";

print "-" x 50, "\n";

# \E turns off case shifting
$_ = "I saw Fred with Barney.";
print "\$_ = '$_'\n";
print 'Substitution Pattern =  s/(\w+) with (\w+)/\U$2\E with $1/i',"\n";
s/(\w+) with (\w+)/\U$2\E with $1/i;
print "\$_ = '$_'\n";

print "-" x 50, "\n";

# \E turns off case shifting. Without it, 'BARNEY WITH FRED' will be all capitalized.
$_ = "I saw Fred with Barney.";
print "\$_ = '$_'\n";
print 'Substitution Pattern =  s/(\w+) with (\w+)/\U$2 with $1/i',"\n";
s/(\w+) with (\w+)/\U$2 with $1/i;
print "\$_ = '$_'\n";

print "-" x 50, "\n";

# \u replaces the next character and changes it to Upper Case. Used for capitalizing the beginning of a word.
$_ = "I saw fred with barney.";
print "\$_ = '$_'\n";
print 'Substitution Pattern =  s/(fred|barney)/\u$1/gi',"\n";
s/(fred|barney)/\u$1/gi;
print "\$_ = '$_'\n";

print "-" x 50, "\n";

# \l replaces the next character and changes it to Lower Case. Used for uncapitalizing the beginning of a word.
$_ = "I saw FRED with BARNEY.";
print "\$_ = '$_'\n";
print 'Substitution Pattern =  s/(fred|barney)/\l$1/gi',"\n";
s/(fred|barney)/\l$1/gi;
print "\$_ = '$_'\n";

print "-" x 50, "\n";

# We can stack these backslash escapes. \u with \L means "all lowercase, but capitalize the first letter."
$_ = "I saw fRED with bArNeY.";
print "\$_ = '$_'\n";
print 'Substitution Pattern =  s/(fred|barney)/\u\L$1/gi',"\n";
s/(fred|barney)/\u\L$1/gi;
print "\$_ = '$_'\n";

print "done.\n";