How to get the value of a two-dimensional array in php

In php, a two-dimensional array is an array composed of multiple one-dimensional arrays, where each one-dimensional array contains multiple key-value pairs. When dealing with two-dimensional arrays, we usually need to get the value of a specific key in the array in order to operate on it. In this article, we will introduce several methods of obtaining two-dimensional array values ​​in PHP.

1. Using foreach loop

Using foreach loop to traverse a two-dimensional array is one of the most commonly used methods in PHP. Each iteration in the loop, we can access the value of a specific element in that array using the key name and pass it to other variables for further processing. The following is a sample code that uses a foreach loop to obtain the value of a two-dimensional array element:

$students = array(
    array("name" => "Alice", "age" => 20),
    array("name" => "Bob", "age" => 21),
    array("name" => "Charlie", "age" => 22)
);

foreach ($students as $student) {
    echo "Name: " . $student['name'] . " Age: " . $student['age'] . "
";
}

The above code will output the following:

Name: Alice Age: 20
Name: Bob Age: 21
Name: Charlie Age: 22

2. Using a for loop

In addition to using foreach loop, we can also use for loop to access two-dimensional array elements. For a two-dimensional array, we need to use two nested for loops to traverse both dimensions. The following is a sample code that uses a for loop to obtain the element value of a two-dimensional array:

$students = array(
    array("name" => "Alice", "age" => 20),
    array("name" => "Bob", "age" => 21),
    array("name" => "Charlie", "age" => 22)
);

$num_students = count($students);

for ($i = 0; $i < $num_students; $i++) {
    echo "Name: " . $students[$i]['name'] . " Age: " . $students[$i]['age'] . "
";
}

The output result is the same as the above code using a foreach loop:

Name: Alice Age: 20
Name: Bob Age: 21
Name: Charlie Age: 22

3. Use the array_column function

If we only want to get the value of a specific key in a two-dimensional array, we can use the array_column function. This function returns a one-dimensional array of values ​​for the specified key in the specified array. The following is a sample code that uses the array_column function to get the value of a two-dimensional array element:

$students = array(
    array("name" => "Alice", "age" => 20),
    array("name" => "Bob", "age" => 21),
    array("name" => "Charlie", "age" => 22)
);

$ages = array_column($students, 'age');

print_r($ages);

The above code will output the following:

Array ( [0] => 20 [1] => 21 [2] => 22 )

4. Using the array_map function

$students = array(
    array("name" => "Alice", "age" => 20),
    array("name" => "Bob", "age" => 21),
    array("name" => "Charlie", "age" => 22)
);

function get_age($student) {
    return $student['age'];
}

$ages = array_map('get_age', $students);

print_r($ages);

Array ( [0] => 20 [1] => 21 [2] => 22 )

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