PHP学习笔记：数组的使用与操作

//使用array()函数创建索引数组
$fruits = array("apple", "banana", "orange");

//使用简写形式创建索引数组
$fruits = ["apple", "banana", "orange"];

//使用array()函数创建关联数组
$person = array("name" => "Tom", "age" => 25, "city" => "Beijing");

//使用简写形式创建关联数组
$person = ["name" => "Tom", "age" => 25, "city" => "Beijing"];

$fruits = ["apple", "banana", "orange"];

echo $fruits[0]; //输出：apple
echo $fruits[1]; //输出：banana
echo $fruits[2]; //输出：orange

$person = ["name" => "Tom", "age" => 25, "city" => "Beijing"];

echo $person["name"]; //输出：Tom
echo $person["age"]; //输出：25
echo $person["city"]; //输出：Beijing

$fruits = ["apple", "banana", "orange"];

$fruits[] = "grape"; //将"grape"添加到末尾
$fruits[1] = "pear"; //将"pear"替换索引为1的元素

print_r($fruits);

$person = ["name" => "Tom", "age" => 25];

$person["city"] = "Beijing"; //添加键值对

print_r($person);

$fruits = ["apple", "banana", "orange"];

unset($fruits[1]); //删除索引为1的元素

print_r($fruits);

$person = ["name" => "Tom", "age" => 25, "city" => "Beijing"];

unset($person["age"]); //删除键为"age"的元素

print_r($person);

$fruits = ["apple", "banana", "orange"];

//使用for循环遍历索引数组
for($i = 0; $i < count($fruits); $i++){
    echo $fruits[$i] . " ";
}

//使用foreach循环遍历索引数组
foreach($fruits as $fruit){
    echo $fruit . " ";
}

$person = ["name" => "Tom", "age" => 25, "city" => "Beijing"];

//使用foreach循环遍历关联数组
foreach($person as $key => $value){
    echo $key . ": " . $value . " ";
}

$numbers = [3, 1, 2];

sort($numbers); //升序排序

print_r($numbers);

rsort($numbers); //降序排序

print_r($numbers);