學習使用PHP數(shù)組
Jun 21, 2016 am 09:14 AM
數(shù)組
PHP4.0中共有超過30個新的數(shù)組相關(guān)函數(shù)。其中很多通用函數(shù)允許你檢查給定數(shù)組中是否存在特定對象、對數(shù)組元素計數(shù)、增加或刪除元素，或?qū)υ嘏判颉?br>
如果你有很大的一個數(shù)組，而所要完成的僅是找出一個存在的給定值，你可以使用in_array()以返回true 或 false。如下代碼將輸出“Not found in this array”——因為你將在$namesArray中尋找一個并不存在的“Alber ”。
$namesArray = array("Joe", "Jane", "Bob", "Mary", "Paul", "Eddie", "John");
$lookingFor = "Albert";
if (in_array($lookingFor, $namesArray)) {
echo "You've found it!";
} else {
echo "Not found in this array!";
}
?>
如果你改變了$lookingFor的值，將其變?yōu)椤癕ary”，你將得到消息“You've found it!”——因為“Mary”是$namesArray的一部分。
如果希望對數(shù)組元素計數(shù)，你可以使用count()函數(shù)：
$namesArray = array("Joe", "Jane", "Bob", "Mary", "Paul", "Eddie", "John");
$count = count($namesArray); ?>
$count值將為7。
你可以對任何數(shù)組添加元素，無論是在已存在數(shù)組的開始或末尾。你也可以使用函數(shù)以創(chuàng)建一個包含兩個或多個數(shù)組元素的新數(shù)組。合并時每個數(shù)組將按需要的順序排列。如果你的數(shù)組已經(jīng)有內(nèi)部的排序，你需要對新的合并數(shù)組重排序。
讓我們從對已存在數(shù)組的末尾增添元素開始，使用函數(shù)array_push()：
/* 創(chuàng)建原始數(shù)組 */
$fruitArray = array("apple", "orange", "banana", "kiwi", "pear");
/* 加入到原始數(shù)組中 */
array_push($fruitArray, "grape", "pineapple", "tomato");
/* 通過其鍵值列出每個元素*/
while (list($key,$value) = each($fruitArray)) {
echo "$key : $value
";
}
?>
這將顯示：
0 : apple
1 : orange
2 : banana
3 : kiwi
4 : pear
5 : grape
6 : pineapple
7 : tomato
當你需要對數(shù)組開頭添加元素時，代碼非常類似。不同處只是函數(shù)名：array_unshift() 而不是array_push()。
/* 創(chuàng)建原始數(shù)組 */
$fruitArray = array("apple", "orange", "banana", "kiwi", "pear");
/* 加入到原始數(shù)組中 */
array_unshift($fruitArray, "grape", "pineapple", "tomato");
/* 通過其鍵值列出每個元素*/
while (list($key,$value) = each($fruitArray)) {
echo "$key : $value
";
}
?>
這將顯示：
0 : grape
1 : pineapple
2 : tomato
3 : apple
4 : orange
5 : banana
6 : kiwi
7 : pear
函數(shù)array_merge()合并兩個或更多的數(shù)組。
/* 創(chuàng)建原始數(shù)組 */
$fruitArray = array("apple", "orange", "banana", "kiwi", "pear");
/* 創(chuàng)建第二個數(shù)組 */
$vegArray = array("carrot", "green beans", "asparagus", "artichoke", "corn");
/* 合并為一個數(shù)組 */
$goodfoodArray = array_merge($fruitArray, $vegArray);
/* 通過其鍵值列出每個元素*/
while (list($key,$value) = each($goodfoodArray)) {
echo "$key : $value
";
}
?>
這將顯示：
0 : apple
1 : orange
2 : banana
3 : kiwi
4 : pear
5 : carrot
6 : green beans
7 : asparagus
8 : artichoke
9 : corn
現(xiàn)在已經(jīng)對數(shù)組進行了增加元素和合并，現(xiàn)在來練習刪除元素函數(shù)。你可以使用函數(shù)array_pop()從一數(shù)組末尾刪除一個元素。如果使用函數(shù)array_shift()，則從一數(shù)組開頭刪除一個元素。而實際上當你從數(shù)組刪除元素時，此元素對你而言仍然可用——當你從已存在的數(shù)組中對元素進行pop 或 shift時。
使用array_pop()函數(shù)從數(shù)組末尾刪除一個值：
/* 創(chuàng)建一數(shù)組*/
$fruitArray = array("apple", "orange", "banana", "kiwi", "pear");
/* 在末尾彈出某值 */
$popped = array_pop($fruitArray);
/* 列出新數(shù)組內(nèi)容，以及彈出的值*/
while (list($key,$value) = each($fruitArray)) {
echo "$key : $value
";
}
echo "
and finally, in $popped: $popped";
?>
這將顯示：
0 : apple
1 : orange
2 : banana
3 : kiwi
and finally, in $popped: pear
Next, delete an element from the end of an array: ？？？？？？？？？？？
下面，從數(shù)組末尾刪除某值：
/* 創(chuàng)建一數(shù)組*/
$fruitArray = array("apple", "orange", "banana", "kiwi", "pear");
/* 從數(shù)組頭部移出某值 */
$shifted = array_shift($fruitArray);
/* 列出新數(shù)組的內(nèi)容以及移出的值*/
while (list($key,$value) = each($fruitArray)) {
echo "$key : $value
";
}
echo "
and finally, in $shifted: $shifted";
?>
這將顯示：
0 : orange
1 : banana
2 : kiwi
3 : pear
and finally, in $shifted: apple
有很多函數(shù)可以幫助你對數(shù)組元素排序。但我將會演示基本的排序以幫助你了解其過程：
/* 創(chuàng)建原始數(shù)組 */
$fruitArray = array("apple", "orange", "banana", "kiwi", "pear");
/* 排序 */
sort($fruitArray);
/* 對其重設(shè)以正確從頭到尾顯示數(shù)組 */
/* 通過其鍵值列出每個元素*/
while (list($key,$value) = each($fruitArray)) {
echo "$key : $value
";
}
?>
這將顯示：
0 : apple
1 : banana
2 : kiwi
3 : orange
4 : pear
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