How to query specific characters in an array in php

In PHP, array is a very commonly used data structure, which can store different types of values, such as integers, strings, Boolean values, etc. When processing data, we often need to find whether specific characters or elements exist in an array in order to perform related operations. This article will introduce how to query specific characters in an array in PHP.

1. Query a single element in the array

1. Use the in_array() function to query whether a specific element exists in the array.

The in_array() function can determine whether an array contains a specified value and returns a Boolean value. If it exists, it returns true, otherwise it returns false. For example, we have an array $fruit, which contains three elements: apples, bananas, and oranges.

$fruit = array("苹果", "香蕉", "橘子");

We want to query whether the banana element exists in the array. You can use the following code:

$exist = in_array("香蕉", $fruit);
if ($exist) {
  echo "该元素存在于数组中";
} else {
  echo "该元素不存在于数组中";
}

The result of the above code is: "This element exists in the array."

2. Use the array_search() function to query whether a specific element exists in the array.

The array_search() function is used to find the specified value in the array. If it exists, it returns the key name of the value, otherwise it returns false. For example, we use the following code to query whether there is an apple element in the above array:

$key = array_search("苹果", $fruit);
if ($key !== false) {
  echo "指定元素在数组中的键名为：" . $key;
} else {
  echo "该元素不存在于数组中";
}

The result of the above code is: "The key name of the specified element in the array is: 0".

2. Query multiple elements in an array

When you need to query whether multiple elements in an array exist, neither of the above two methods is very convenient. PHP provides an array_intersect() function to find the intersection of two or more arrays (i.e., the elements they contain together). We can use this function to filter out specific elements in the array.

For example, there are two arrays $fruit and $wanted, where $fruit contains four fruits: apples, bananas, oranges and grapes, and $wanted contains the names of the fruits we want to query, such as apples and tangerine. We need to query whether the elements in the $wanted array exist in the $fruit array.

$fruit = array("苹果", "香蕉", "橘子", "葡萄");
$wanted = array("苹果", "橘子");
$common = array_intersect($fruit, $wanted);
if (count($common) > 0) {
  echo "查找到以下元素：";
  foreach ($common as $value) {
    echo $value . " ";
  }
} else {
  echo "未查询到任何元素";
}

The result of running the above code is: "The following elements were found: apple orange".

It should be noted that the result returned by the array_intersect() function is a new array, which contains the common elements in the two arrays. When operating on the returned results, you need to use the foreach() loop statement to traverse.

3. Summary

Querying specific characters in an array is one of the common operations in PHP. This article introduces the method of querying a single element and multiple elements of an array. In actual development, we can choose different methods according to specific needs. It should be noted that when the array size is large, the efficiency of traversing the entire array to query elements may be reduced. In this case, we can consider using other data structures for optimization.

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