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43 C h a p t e r 2 U s i n g V a r i a b l e s a n d I n p u t value = “pt”>points<br> <input type = “radio” name = “sizeType” value = “cm”>centimeters<br> <input type = “radio” name = “sizeType” value = “in”>inches<br> </td> </tr> </table> <input type = “submit” value = “show me”> </form> </center> </body> </html> The borderMaker.html page is designed to interact with a PHP program called borderMaker.php, as you can see by inspection of the action attribute. Note that I added a value attribute for each option element, and the radio buttons all have the same name but different values. The value attribute becomes very important when your program is destined to be read by a program. Finally, the submit button is critical, because nothing interesting happens until the user submits the form. I didn’t include checkboxes in this particular example. I show you how check- boxes work in chapter 3, “Controlling Your Code with Conditions and Functions,” because you need conditional statements to work with them. Conditional state- ments allow your programs to make choices. Reading the Form Elements The borderMaker.php program expects input from borderMaker.html. When the user submits the HTML form, the PHP program produces results like those shown in Figure 2.14. In general, it doesn’t matter what type of element you use on an HTML form. The PHP interpreter simply looks at each element’s name and value. By the time the informa- tion gets to the server, it doesn’t matter what type of input element was used. PHP TRICK automatically creates a variable corresponding to each form element. The value of that variable is the value of the element. The code used in borderMaker.php illustrates: <html> <head> <title>Your Output</title> </head> <body> <h1>Your Output</h1> <center> <? $theStyle = <<<HERE “border-width:$borderSize$sizeType; border-style:$borderStyle; border-color:green” HERE; print “<div style = $theStyle>”; print $basicText; print “</span>”; ?> </center> 44 P H P 5 /M y S Q L P r o g r a m m i n g f o r t h e A b s o l u t e B e g i n n e r FIGURE 2.14 The borderMaker.php code reacts to all the various input elements on the form. </body> </html> In the case of text boxes and text areas, the user types in the value directly. In borderMaker.html, there is a text area called basicText. The PHP interpreter cre- ates a variable called $basicText. Anything typed into that text box (as a default the first few lines of the Gettysburg Address ) becomes the value of the $basicText variable. Reading Select Elements Recall that both drop-down lists and list boxes are created with the select object. That object has a name attribute. Each of the possible choices in the list box is an option object. Each option object has a value attribute. The name of the select object becomes the variable name. For example, border- Maker.html has two select objects: borderSize and borderStyle. The PHP program can expect to find two corresponding variables: $borderSize and $borderStyle. Because the user has nowhere to type a value into a select object, the values it can return must be encoded into the structure of the form itself. The value of whichever option the user selected is sent to the PHP program as the value of the corresponding variable. For example, if the user chose groove as the border style, the $borderStyle variable has the value groove in it. You can have multiple selections enabled in a list box. In that case, the variable contains a list of responses. While managing this list is not difficult, it is a topic for another chapter (chapter 4, “Loops and Arrays,” to be specific). For now, concentrate on the singular list box style. TRAP 45 C h a p t e r 2 U s i n g V a r i a b l e s a n d I n p u t IN THE REAL WORLD The options’ value doesn’t necessarily have to be what the user sees on the form. This “hidden value” is handy if you want to show the user one thing but send something else to the server. For example, you might want to let the user choose from several colors. In this case, you might want to create a list box that shows the user several color names, but the value property corresponding to each of the option objects might have the actual hexadecimal values. Similar tricks are used in online shopping environments, where you might let the user choose an item by its name but the value associated with that item might be its catalog number, which is easier to work with in a database environment. Reading Radio Groups CSS allows the developer to indicate sizes with a variety of measurements. This is an ideal place for a group of radio buttons because only one unit of measure is appro- priate at a time. Even though there are four different radio buttons on the borderDemo.html page with the name sizeType, the PHP program will only see one $sizeType variable. The value associated with whichever option is selected will become the value of the $sizeType variable. Note that like option elements, it is pos- sible for the value of a radio button to be different than the text displayed beside it. Returning to the Story Program The Story program introduced at the beginning of this chapter is an opportunity to bring together all the new elements you learned. The program doesn’t intro- duce anything new, but it helps you see a larger context. Designing the Story Even though this is not an especially difficult program to write, you run into prob- lems if you simply open your text editor and start blasting away. It really pays to plan ahead. The most important thinking happens before you write a single line of code. 46 P H P 5 /M y S Q L P r o g r a m m i n g f o r t h e A b s o l u t e B e g i n n e r DECIDING ON A FORM ELEMENT You might wonder if all these form elements are necessary, since they all boil down to a name and value by the time they get to the PHP interpreter. The var- ious kinds of user interface elements do make a difference in a few ways: • It’s easier (for many users) to use a mouse than to type. Whenever possible, it is nice to add lists, checks, and options so the user can navigate your forms more quickly. Typing is often much slower than the kinds of input afforded by the other elements. • Interface elements (especially the drop-down list box) are extremely effi- cient in terms of screen space. You can pack a lot of choices on a small screen by using drop-downs effectively. While you might not think space is an issue, take a look at how many people are now surfing the Web with PDAs and cell phones. • Your life as a programmer is much easier if you can predict what the user will send. When users type things, they make spelling and grammar mis- takes, use odd abbreviations, and are just unpredictable. If you limit choices whenever possible, you are less likely to frustrate users. In this situation, start by thinking about your story. You can write your own story or modify some existing text for humorous effect. I raided a nursery rhyme book for my story. Regardless of how you come up with a story, have it in place before you start writing code. I wrote the original unmodified version of “Little Boy Blue” in my text editor first so I could admire its artistic genius—and then mangle it beyond recognition. As you look over the original prose, look for key words you can take out, and try to find a description that hints at the original word without giving anything away. For example, I printed my story, circled the word blue in the original poem, and wrote color on another piece of paper. Keep doing this until you’ve found several words you can take out of the original story. You should have a document with a bunch of holes in it, and a list of hints. Mine looked like Figure 2.15. 47 C h a p t e r 2 U s i n g V a r i a b l e s a n d I n p u t FIGURE 2.15 I thought through the story and the word list before writing any code. IN THE REAL WORLD Figure 2.15 shows the plan written as a Word document. Although things are sometimes done this way…(especially in a professional programming environ- ment), I really wrote the plan on paper. I reproduced it in a cleaner format because you don’t deserve to be subjected to my handwriting. I usually plan my programs on paper, chalkboard, or dry erase board. I avoid planning programs on the computer, because it’s too tempting to start program- ming immediately. It’s important to make your plan describe what you wish to do in English before you worry about how you’ll implement the plan. Most beginners (and a lot of pros) start programming way too early, and get stuck as a result. You see, throughout the rest of this chapter, how this plan evolves into a working program. . me”> </form> </center> </body> </html> The borderMaker.html page is designed to interact with a PHP program called borderMaker .php, as you can see by inspection of the action attribute. Note that I added a value. choices. Reading the Form Elements The borderMaker .php program expects input from borderMaker.html. When the user submits the HTML form, the PHP program produces results like those shown in Figure. HTML form. The PHP interpreter simply looks at each element’s name and value. By the time the informa- tion gets to the server, it doesn’t matter what type of input element was used. PHP TRICK automatically
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