How to find whether a certain value exists in a two-dimensional array in php

PHP Two-dimensional array to find whether a certain value exists

In PHP, array is one of the commonly used data types, and two-dimensional array is one of the more commonly used array forms. In actual development, we often need to find whether a certain value exists in a two-dimensional array. This article will introduce several implementation methods.

1. Use foreach loop

First, we can use foreach loop to traverse the entire two-dimensional array and find whether the target value exists one by one. The code is as follows:

function search_array($array, $search_value)
{
    foreach($array as $value)
    {
        if(in_array($search_value, $value))
        {
            return true;
        }
    }
    return false;
}

In the above code, we define a function named search_array, which receives two parameters. $array represents the two-dimensional array to be searched, and $search_value represents the value to be searched.

In the function body, we first use a foreach loop to traverse the two-dimensional array, taking out an array element $value each time, and then use the in_array function to check whether $search_value exists in $value. If it exists, the function returns true , indicating that the target value has been found; otherwise, the loop continues until the array traversal is completed.

Note: The in_array() function is used to search for a given value in an array. Returns true if found, false otherwise.

2. Using the array_walk function

In addition to using the foreach loop, we can also use the array_walk function to process each array element and check whether the target value exists. The code is as follows:

function search_array($array, $search_value)
{
    $found = false;
    array_walk($array, function($value) use (&$found, $search_value){
        if(in_array($search_value, $value))
        {
            $found = true;
        }
    });
    return $found;
}

In the above code, we first define a function named search_array, which receives two parameters: $array represents the two-dimensional array to be searched, and $search_value represents the value to be searched. We also define a variable $found, which indicates whether the target value is found, and is initialized to false.

Then, we called the array_walk function to traverse the $array array. Here we used an anonymous function as a callback function. The function received the $value parameter to represent the array element, and used the use statement to pass $found and $search_value in. , use the in_array function in the function body to check whether $search_value exists in $value. If it exists, set $found to true, indicating that the target value is found. Finally, the function returns the value of $found, indicating whether the target value was found.

Note: The array_walk() function applies a user-defined function to each element in the array. Returns TRUE if successful, FALSE otherwise.

3. Use the array_reduce function

Finally, we can also use the array_reduce function to traverse the entire two-dimensional array and check whether each array element contains the target value one by one. The code is as follows:

function search_array($array, $search_value)
{
    $found = array_reduce($array, function($carry, $value) use ($search_value){
        return $carry || in_array($search_value, $value);
    }, false);
    return $found;
}

In the above code, we first define a function named search_array, which receives two parameters: $array represents the two-dimensional array to be searched, and $search_value represents the value to be searched.

Then, we use the array_reduce function to traverse the entire two-dimensional array, using an anonymous function as the callback function, where $carry represents the return value of the previous iteration, and $value represents the array element currently iterated to. The in_array function is used in the function body to check whether $search_value exists in $value. If it exists, $carry || true is returned, indicating that the target value has been found; otherwise, $carry || false is returned, indicating that the target value has not been found. Finally, the function returns the value of $found, indicating whether the target value was found.

Note: The array_reduce() function uses a callback function to iteratively reduce the array to a single value.

Summary

This article introduces three ways to implement a PHP two-dimensional array to find a certain value. It uses the foreach loop, array_walk function and array_reduce function to traverse the two-dimensional array respectively and check whether it contains the target. value. In actual development, we should choose an appropriate implementation method based on the actual situation to improve code efficiency and execution speed.

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