Listing:

$message="Welcome to my web site";
print substr($message,14,3),"\n";
print index($message," "),"\n";
print rindex($message," "),"\n";
print rindex($message," ",12),"\n";
print substr($message,index($message,"my")),"\n";
substr($message,0,0)="Hello and ";
print "$message \n";
substr($message,10,1)="w";
substr($message,-1,1)="e!";
print "$message\n";
print "uc($message) = ",uc($message),"\n";
print "lc($message) = ",lc($message),"\n";
print "length($message) = ",length($message),"\n";

Output:

web
7
17
10
my web site
Hello and Welcome to my web site
Hello and welcome to my web site!
uc(Hello and welcome to my web site!) = HELLO AND WELCOME TO MY WEB SITE!
lc(Hello and welcome to my web site!) = hello and welcome to my web site! length(Hello and welcome to my web site!) = 33