How to output the key value of an array in php

PHP is a programming language widely used for writing server-side web applications, and arrays are one of its common data types. In PHP, you can use the following methods to output the key values ​​of an array:

1. Use the print_r() function

The print_r() function is used to print information about variables Easy-to-understand information, including types and values ​​of variables. For array type variables, print_r() outputs all elements in the array, including keys and values.

For example, suppose there is an array $fruit. The array elements include apple, banana and orange, and the corresponding keys are 0, 1 and 2. Then you can use the following method to output:

$fruit = array("apple", "banana", "orange");

print_r($fruit);

The output result is:

Array
(
    [0] => apple
    [1] => banana
    [2] => orange
)

2. Use the var_dump() function

The var_dump() function can output the type and value of the variable. Unlike the print_r() function, var_dump The () function also outputs the memory space occupied by the variable and the type of data.

Similar to the print_r() function, for array type variables, var_dump() outputs all elements in the array, including keys and values.

For example, based on the above $fruit array, use the var_dump() function to output:

var_dump($fruit);

The output result is:

array(3) {
  [0]=>
  string(5) "apple"
  [1]=>
  string(6) "banana"
  [2]=>
  string(6) "orange"
}

3. Loop output

Looping is a common method of outputting an array. For an array of key-value pairs, you can use a foreach loop to output each key-value pair. As you iterate through each element, you can use the key (that is, the index in the array) and the value to output.

For example, based on the above $fruit array, it can be output in the following way:

foreach ($fruit as $key => $value) {
    echo "Key: " . $key . ", Value: " . $value . "<br>";
}

The output result is:

Key: 0, Value: apple
Key: 1, Value: banana
Key: 2, Value: orange

The above are the three types of output in PHP Array key value method, different output methods are suitable for different scenarios. Choosing an appropriate method to output array key values ​​according to requirements can improve development efficiency and code quality.

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