Sending Data to the Web Browser
To build dynamic Web sites with PHP, you must know how to send data to the Web browser. PHP has a number of built-in functions for this purpose, the most common being
echo()
and
print()
.
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As you might discover, one of the complications with sending data to the Web involves printing single and double quotation marks. Either of the following will cause errors (
Figure 1.2
):
echo "She said, "How are you?"";
print 'I'm just ducky.';
There are two solutions to this problem. First, use single quotation marks when printing a double quotation mark and vice versa:
echo 'She said, "How are you?"';
print "I'm just ducky.";
Or, you can
escape
the
problematic
character by
preceding
it with a backslash:
echo "She said, \"How are you?\"";
print 'I\'m just ducky.';
Understanding how to use the backslash to escape a character is an important concept, and one I'll cover in more depth at the end of the chapter.
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echo 'Hello, world!';
print "It's nice to see you.";
As you can see from this example, either single or double quotation marks will work with either function (the distinction between the two types of quotation marks will be made clear by the chapter's end). Also note that in PHP all statements (a line of executed code, in layman's terms) must end with a semicolon.
To send data to the Web browser
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1.
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Open
first.php
(refer to Script 1.2) in your text editor.
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2.
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Between the PHP tags (lines 10 and 11), add a simple message (
Script 1.3
).
echo 'This was generated using PHP!';
It truly doesn't matter what message you type here, which function you use (
echo()
or
print()
), or which quotation marks, for that matterjust be careful if you are printing a single or double quotation mark as part of your message (see the sidebar "Looking for an Escape").
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3.
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If you want, change the page title (line 6).
<title>Using Echo()</title>
This is an optional and purely cosmetic change.
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4.
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Save the file as
second.php
, upload to your Web server, and test in your Web browser (
Figure 1.3
).
If you see a parse error instead of your message (see Figure 1.2), check that you have both opened and closed your quotation marks and escaped any problematic
characters
. Also be certain to conclude each statement with a semicolon.
If you see an entirely blank page, this is probably for one of two reasons:
-
There is a problem with your HTML. Test this by viewing the source of your page and looking for HTML problems there (
Figure 1.4
). If you don't know how to view the source, see the instructions at the end of the
next
set of steps.
-
An error occurred, but
display_errors
is turned off in your PHP configuration, so nothing is shown. In this case, see the section in Appendix A on how to configure PHP so that you can
turn
display_errors
back on.
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Tips
-
Technically,
echo()
and
print()
are language constructs, not functions. That being said, don't be surprised as I continue to call them "functions" for convenience. Also, I include the parentheses when referring to functions to help distinguish them from
variables
and other
parts
of PHP. This is just my own little convention.
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You can also use
echo()
and
print()
to send HTML code to the Web browser, like so (
Figure 1.5
):
echo '<b>Hello, <font size="+2">
world</font>!</b>';
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PHP is case-insensitive when it comes to function
names
, so
ECHO()
,
echo()
,
eCHo()
, and so forth will all work.
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With
echo()
but not
print()
, you can send multiple, separate
chunks
of data to the Web browser using commas:
echo 'Hello, ', 'world!';
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Echo()
and
print()
can both be used to print text over multiple lines, as you'll see.
-
I prefer to use
echo()
over
print()
, for no particular reason. If you prefer
print()
, you can replace any reference I make to
echo()
with
print()
without a problem.
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