Page 176 - Beginning PHP 5.3

Part II: Learning the Language
A classic use of list() is with functions such as each() that return an indexed array of values. For
example, you could rewrite the each() example from “ Stepping Through an Array, ” earlier in this
chapter, to use list() :

$myBook = array( “title” = > “The Grapes of Wrath”,
“author” = > “John Steinbeck”,
“pubYear” = > 1939 );

while ( list( $key, $value ) = each( $myBook ) ) {
echo “ < dt > $key < /dt > ”;
echo “ < dd > $value < /dd > ”;

}
Summary
This chapter has introduced you to another important concept: arrays. These are special variables that
can store more than one value, and you ’ ll find that you use them all the time in your PHP scripts.

First you delved into the anatomy of arrays, and learned the concepts of indexed and associative arrays.
Then you learned how to create arrays in PHP, and access array elements using both square brackets and
array_slice() . Along the way you learned about a very useful PHP function, print_r() , that you
can use to output entire arrays for debugging purposes.

Next, you discovered that every PHP array has an internal pointer that references its elements, and you
learned how to use this pointer to move through the elements in an array using current() , key() ,
next() , prev() , end() , and reset() . You also used the handy foreach looping construct to loop
through elements in an array.

Arrays get really powerful when you start nesting them to produce multidimensional arrays. You
studied how to create such arrays, as well as how to access their elements and loop through them.

Finally, you explored some of PHP ’ s powerful array - manipulation functions, including:
❑ Sorting functions — You looked at functions such as sort() , asort() , ksort() and
array_multisort()
❑ Functions for adding and removing elements — These include array_unshift() , array_
shift() , array_push() , array_pop() and array_splice()

❑ array_merge() – – This function is useful for merging two or more arrays together
❑ explode() and implode() — These let you convert between arrays and strings

❑ list() – – You can use this to store array elements in a list of individual variables

PHP has a lot more array - related functions than the ones covered in this chapter. It ’ s a good idea to
explore the online PHP manual at http://www.php.net/types.array to get an overview of the other
array functions that PHP has to offer. Also, try the following two exercises to test your array
manipulation skills. You can find the solutions to these exercises in Appendix A.
The next chapter looks at the concept of functions in PHP, and shows you how to create your own
functions and build reusable chunks of code.

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