{"id":1299,"date":"2018-01-19T19:22:40","date_gmt":"2018-01-19T19:22:40","guid":{"rendered":"http:\/\/goofy-trucks.flywheelsites.com\/arrays-101\/"},"modified":"2018-01-19T19:24:40","modified_gmt":"2018-01-19T19:24:40","slug":"arrays-101","status":"publish","type":"post","link":"https:\/\/phpbuilder.com\/arrays-101\/","title":{"rendered":"Arrays 101"},"content":{"rendered":"
\n
\n
By Joshua Petrovich<\/div>\n
on April 24, 2003<\/div>\n<\/p><\/div>\n
\n
\nIf you’ve ever created large scripts that require many variables (sometimes nearly 100), you know
\nwhat it’s like trying to keep track of what each variable contains and what it’s used for. Trust me,
\nI’ve been there. If we can store those variables inside other<\/i> variables then the list of hundereds
\nshrinks to less than 10. That’s where arrays come in.\n<\/div>\n
An array, broken down to its simplest form, is simply a variable that holds
\nvariables. It’s kind of like a bunch of houses in a city. The city contains many houses and each house
\nhas an address. In the same manner, each variable (house) within the array (city) has its own address
\ncalled an index<\/i>.\n<\/div>\n
Let’s say you have the names of three persons (John, Susie, and Dave)
\nstored in the variables named $sPerson1<\/code>, $sPerson2<\/code>,
\nand $sPerson3<\/code> respectively. Now you can use
\nthose three variables within your program, but it’s easy to lose track of which one is which…
\nespecially if you have other variables. To compact the three variables into an array, you’d do something like this:\n<\/div>\n
\n<\/p>\n

<?php
\n
\u00a0\u00a0\u00a0\u00a0$arrayPeople\u00a0<\/span>=\u00a0array(<\/span>\"John\"<\/span>,\u00a0<\/span>\"Susie\"<\/span>,\u00a0<\/span>\"Dave\"<\/span>);
\n
<\/span>?>
\n
<\/span>
\n<\/span>
\n<\/code><\/font><\/div>\n

\nNow instead of using $sPerson1<\/code>, $sPerson2<\/code>,
\nand $sPerson3<\/code> I can use $arrayPeople<\/code>. Note
\nhow I created the array using the array()<\/code> function included with PHP.
\nIf those three names were numbers instead, I wouldn’t surround the number with quotes. So now to print
\nthose three names I’d do this:\n<\/div>\n
\n<\/p>\n

<?php
\n
\u00a0\u00a0\u00a0\u00a0$arrayPeople\u00a0<\/span>=\u00a0array(<\/span>\"John\"<\/span>,\u00a0<\/span>\"Susie\"<\/span>,\u00a0<\/span>\"Dave\"<\/span>);
\n
\u00a0\u00a0\u00a0\u00a0print\u00a0<\/span>$arrayPeople<\/span>[<\/span>0<\/span>];
\n
\u00a0\u00a0\u00a0\u00a0print\u00a0<\/span>$arrayPeople<\/span>[<\/span>1<\/span>];
\n
\u00a0\u00a0\u00a0\u00a0print\u00a0<\/span>$arrayPeople<\/span>[<\/span>2<\/span>];
\n
<\/span>?>
\n
<\/span>
\n<\/span>
\n<\/code><\/font><\/div>\n

Why did he start with zero?<\/i> Because that’s where the index starts. Whatever
\ngets put into the array is assigned an index of zero(0) and that number automatically increments from there.
\nYou can manually assign an index for a particular entry, but I’ll cover that later. For now, I’ll show you
\nhow to use a loop to automatically print the contents of an entire array:\n<\/div>\n
\n<\/p>\n

<?php
\n
\u00a0\u00a0\u00a0\u00a0$arrayPeople\u00a0<\/span>=\u00a0array(<\/span>\"John\"<\/span>,\u00a0<\/span>\"Susie\"<\/span>,\u00a0<\/span>\"Dave\"<\/span>);
\n
\u00a0\u00a0\u00a0\u00a0<\/span>$nArraySize\u00a0<\/span>=\u00a0<\/span>count<\/span>(<\/span>$arrayPeople<\/span>);
\n
\u00a0\u00a0\u00a0\u00a0for(<\/span>$index<\/span>=<\/span>0<\/span>;\u00a0<\/span>$index\u00a0<\/span><\u00a0<\/span>$nArraySize<\/span>;\u00a0<\/span>$index<\/span>++)\u00a0<\/span>\/\/\u00a0max.\u00a0index\u00a0is\u00a0always\u00a0number\u00a0of\u00a0entries\u00a0-\u00a01
\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\/\/\u00a0because\u00a0index\u00a0starts\u00a0at\u00a0zero
\n
\u00a0\u00a0\u00a0\u00a0<\/span>{
\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0print\u00a0<\/span>$arrayPeople<\/span>[<\/span>$index<\/span>];
\n
\u00a0\u00a0\u00a0\u00a0}
\n
<\/span>?>
\n
<\/span>
\n<\/span>
\n<\/code><\/font><\/div>\n

\nIn this case, $index<\/code> is the index (address) for the entry and
\n$nArraySize<\/code> is the number of entries in the array. The count()
\nfunction returns the number of entries in the array. Now for very small array like the one I just
\nused, using a loop actually uses more code, but when you start dealing with arrays that have hundereds
\nor even thousands of entries (they do exist), you’ll be glad that you’re using a loop.\n<\/div>\n
This is where I talk about creating your own indexes for array entries.
\nWhenever I use SESSIONS for administrator access areas of my website, I use an array to store
\nsession information. Here’s what the code looks like:<\/div>\n
\n<\/p>\n

<?php
\n
\u00a0\u00a0\u00a0\u00a0$SESSION<\/span>=\u00a0array();\u00a0<\/span>\/\/\u00a0that\u00a0creates\u00a0a\u00a0blank\u00a0array
\n
\u00a0\u00a0\u00a0\u00a0<\/span>$SESSION<\/span>[<\/span>\"username\"<\/span>]\u00a0=\u00a0<\/span>$sUserName<\/span>;
\n
\u00a0\u00a0\u00a0\u00a0<\/span>$SESSION<\/span>[<\/span>\"password\"<\/span>]\u00a0=\u00a0<\/span>$sPassword<\/span>;
\n
\u00a0\u00a0\u00a0\u00a0<\/span>$SESSION<\/span>[<\/span>\"accesslevel\"<\/span>]\u00a0=\u00a0<\/span>$nLevel<\/span>;
\n
\u00a0\u00a0\u00a0\u00a0<\/span>\/\/\u00a0etc,etc,etc.
\n
<\/span>?>
\n
<\/span>
\n<\/span>
\n<\/code><\/font><\/div>\n

You see how I used words to identify the index? This way I know that
\n$SESSION[\"username\"]<\/code> contains the username of the person.
\nIt’s a lot easier than trying to remember that $SESSION[0]<\/code> contains
\nthe username. My way of coding arrays like this is to use the name of the variable as the index
\nfor that entry. So to store $nDaysinMay<\/code> in array
\n$arrayDays<\/code> I’d put it in $arrayDays[\"nDaysinMay\"]<\/code>.
\nThis way I can even keep track of which variable that entry contains. Now this is where I can dive into multi-dimensional arrays.\n<\/div>\n<\/div>\n

<\/p>\n

\n
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If you’ve ever created large scripts that require many variables (sometimes nearly 100), you know what it’s<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[],"class_list":["post-1299","post","type-post","status-publish","format-standard","hentry","category-tutorials"],"_links":{"self":[{"href":"https:\/\/phpbuilder.com\/wp-json\/wp\/v2\/posts\/1299","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/phpbuilder.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/phpbuilder.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/phpbuilder.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/phpbuilder.com\/wp-json\/wp\/v2\/comments?post=1299"}],"version-history":[{"count":1,"href":"https:\/\/phpbuilder.com\/wp-json\/wp\/v2\/posts\/1299\/revisions"}],"predecessor-version":[{"id":3191,"href":"https:\/\/phpbuilder.com\/wp-json\/wp\/v2\/posts\/1299\/revisions\/3191"}],"wp:attachment":[{"href":"https:\/\/phpbuilder.com\/wp-json\/wp\/v2\/media?parent=1299"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/phpbuilder.com\/wp-json\/wp\/v2\/categories?post=1299"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/phpbuilder.com\/wp-json\/wp\/v2\/tags?post=1299"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}