#this is a comment

print "hello bonnie\n";
print "hello \"anne\"\n";  #escape characters
#Perl is case sensitive, try PRINT, it won't work

#Literal data = things do not change
#Numbric literals (numbers) and string literals

#Numbers
print 6;		#integer
print "\n";		#new line
print 12.6;		#floating point number
print "\n";		
print 15.;		#another floating point number
print "\n";		
print .732;		#yet another floating point number
print "\n";		
print 1e10;		#scientific notation
print "\n";		
print 6.67E-33;	#scientific notation (e or E is acceptable)
print "\n";	
print 4_294_296;#large number with underscores instead of commas because we cannot put commas into numeric literals
print "\n\n";	

#Strings, single quotation marks or double quotation marks
print "foo!\n";
print "Four thousand years ago\n";
print 'Four thousand years ago\n'; #character in single quote means exactly what it is there, except \'
print "\n";
print 'Four thousand years ago, he said "make my day."';
print "\n";
print "Four thousand years ago, he said \"make my day.\""; #\ escape
print "";

#Escape characters
print "\n"; #newline
print "\r"; #carriage return
print "\tone\ttwo\tthree\n";	#\t tab
print "\uuppercase\n"; #\u change next char to uppercase
print "\lLOWERCASE\n"; #\l change next char to lowercase
print "\\ \' \""; #literal backslash, literal ', literal "
print "\n";
#may skip from here from escape characters
print "first";
print "\r"; #carriage return, return to first character of line, weird
print "hi";
print "\n";
print "not important";
print "\b";	#backspace
print "something was gone due to backspace";

#scalar variables - things that change
#variable names are case sensitive (be careful when you type), some are reserved like $_ etc
$myvalue = 888;
print "\n";
print $myvalue;
print "\n$myvalue";
print "\n".$myvalue."\n";;

#special variable $_ value is used as "by default", eg. no variable specified or e.g. pattern matching later
$_ = "Dark side of the force";
print;  #print default value $_

print "\n\n";

#expressions and operators
$radius = 50;
$area = 3.14159 * ($radius**2);
print $area;
print "\n";

#more operators - binary
$a = 5;
$b = 3;
print $a+$b."\n";
print $a-$b."\n";
print $a*$b."\n";
print $a/$b."\n";
print $a**$b."\n"; #power
print $a%$b."\n"; #modulo (remainder)
print "\n";

#unary operators
print int(5.62)."\n"; #return integer part
print length("nose")."\n"; #return length
print lc("DARK SIDE OF THE FORCE")."\n"; #lowercase
print uc("dark side of the force")."\n"; #uppercase
print rand(5)."\n"; #random number from 0 to less than argument
print rand."\n"; #random number from 0 to 1

#angle operator <>, for reading and writing files (later)
print "\nwhat size is your shoe? ";
$size = <STDIN>;  #need to chomp newline character
print "Your shoe size is $size. Thank you!\n";

print "\nwhat size is your shoe? ";
$size = <STDIN>;
chomp $size;
print "Your shoe size is $size. Thank you!\n";