How to output the value of a certain key name in a php array

In PHP, an array is a data structure that can store multiple values. An array can be composed of a set of keys and a set of values. We can access the values ​​in the array through the keys. In this article, I will show you how to output the value of a key in a PHP array.

Basics of arrays

An array is an ordered list whose elements can be accessed using numbers or strings as indexes. Arrays can be declared using array(), [] or range(). For example, we can declare an array in the following way:

$fruits = array("apple", "banana", "orange", "grape");

This array is called an indexed array because it uses numbers as keys. Each key corresponds to an element in the array, and the corresponding value can be obtained through indexing. For example:

echo $fruits[0]; // 输出 "apple"
echo $fruits[1]; // 输出 "banana"
echo $fruits[2]; // 输出 "orange"
echo $fruits[3]; // 输出 "grape"

Associative array

In addition to index arrays, there is another commonly used array type - associative array. Associative arrays use string keys instead of numeric indexes. The following is a simple associative array example:

$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");

In the above example, "Peter", "Ben" and "Joe" are called the keys of the array, and their corresponding values ​​are 35, 37 and 43. We can use the following method to output the value in the associative array:

echo $age['Peter']; // 输出 35
echo $age['Ben']; // 输出 37
echo $age['Joe']; // 输出 43

Output the value of a key name in the array

We can use square brackets plus the key name to get the corresponding value in the array value. For an indexed array, the key is a numeric index; for an associative array, the key is a string. For example:

$fruits = array("apple", "banana", "orange", "grape");
echo $fruits[0]; // 输出 "apple"

$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");
echo $age['Peter']; // 输出 35

However, if we want to output all elements in an array, we can use a loop to traverse the array. In PHP, there are three main types of loop statements: for, while and foreach. We can choose different loop statements according to different needs. For example, to traverse the index array, you can use a for loop:

$fruits = array("apple", "banana", "orange", "grape");
for ($i = 0; $i < count($fruits); $i++) {
    echo $fruits[$i]."
";
}

To traverse the associative array, you can use the foreach loop:

$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");

foreach($age as $key => $value) {
    echo "Key = ".$key.", Value = ".$value;
}

In the above example, the $key variable stores the key name of the associative array. , and the $value variable stores the corresponding value. We can output all elements in the associative array through these two variables.

Summary

In PHP, an array is a very useful data structure that can store multiple values ​​and access these values ​​using different index types. If you want to output the value of a key name in the array, you can use square brackets plus the key name; if you want to output the entire array, you can use a loop to traverse each element of the array. Hope this article can be helpful to you.

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