How to find the ranking of a number in an array in php

In many cases, we need to query the ranking of a number in an array. For example, in an array of test scores, we want to know our ranking. In PHP, we can use various methods to achieve this function. Below, I'll introduce some implementation methods.

Method 1: Use array_search function

The array_search function can search for a given value in an array and return the key name where it is located. With the help of this function, we can easily get the position of a certain number in the array, and then compare it with other scores to get the ranking. Here is a sample code:

<?php
$grades = array(85, 90, 73, 79, 92, 88, 75);
rsort($grades); // 按照从高到低的顺序排序
$rank = array_search(79, $grades) + 1;
echo "您的成绩在数组中的排名是第 $rank 名。";
?>

In the above code, the rsort function sorts the array from high to low. Then, we use the array_search function to find the position of the number 79 in the array, and add 1 to get the ranking. Just output the final ranking.

Note: If there are multiple identical numbers in the array, the array_search function will only return the key name of the first matching item. If you need to get the positions of all matching items, you need to loop through the entire array to find them.

Method 2: Use array_flip and asort function

This method requires first using the array_flip function to exchange the keys and values ​​of the original array, and then using the asort function to sort the array in ascending order by value. Then use the array_flip function to swap the keys and values ​​back. Finally, just find the position of the given number in the new array. The following is a sample code:

<?php
$grades = array(85, 90, 73, 79, 92, 88, 75);
$flipped_array = array_flip($grades);
asort($flipped_array);
$rank = array_search(79, $flipped_array) + 1;
echo "您的成绩在数组中的排名是第 $rank 名。";
?>

In the above code, we first exchange the keys and values ​​of the original array, and then sort by value in ascending order. In this way, the key with the smallest value is ranked first, the key with the second smallest value is ranked second, and so on. Finally, just find the position of the given number in the new array and add 1.

Summary:

Both of the above two methods can be used to find the ranking of a certain number in an array. It should be noted that if there are multiple identical numbers in the array, the entire array needs to be traversed to determine its position in the array. In addition, different methods also have different applicable scenarios, and they need to be selected and used according to the actual situation.

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