5_PHP数组_3_数组处理函数及其应用_2_数组统计函数

以下为学习孔祥盛主编的《PHP编程基础与实例教程》（第二版）所做的笔记。

一、数组统计函数

数组统计函数是指统计数组各元素的值，并对这些值进行简单分析。

1. count() 函数

该函数的别名函数为 sizeof()

程序：

<?php
$colors = array("red"=>"red","green",3=>"white",5);
$students = array(
    "2010001"=>
        array("studentNo"=>"2010001","studentName"=>"张三","studentSex"=>"男"),
    "2010002"=>
        array("studentNo"=>"2010002","studentName"=>"李四","studentSex"=>"女"),
    "2010003"=>
        array("studentNo"=>"2010003","studentName"=>"王五","studentSex"=>"男"),
    "2010004"=>
        array("studentNo"=>"2010004","studentName"=>"马六","studentSex"=>"女")
);
$countColors = count($colors);
$countStudents1 = count($students,1);    //mode参数值设为1
$countStudents2 = count($students);    //mode参数值默认值为0
print_r($countColors);  //4
echo "<br/>";
print_r($countStudents1);    //16
echo "<br/>";
print_r($countStudents2);    //4
?>

输出：

4
16
4

 

2. max() 函数

程序：

<?php
$scores = array(70, 80, 90, 60);
$grades = array('A', 'B', 'C', 'D');
$maxScores = max($scores);
$maxGrades = max($grades);
var_dump($maxScores);   //int 90
echo "<br/>";
var_dump($maxGrades);   //string 'D' (length=1)
?>

输出：

D:wampServerwwwApache服务器主目录practise例程.php:6:int 90

D:wampServerwwwApache服务器主目录practise例程.php:8:string 'D' (length=1)

3. min() 函数

程序：

<?php
$scores = array(70, 80, 90, 60);
$grades = array('A', 'B', 'C', 'D');
$minScores = min($scores);
$minGrades = min($grades);
var_dump($minScores);   //int 60
echo "<br/>";
var_dump($minGrades);   //string 'A' (length=1)
?>

输出：

D:wampServerwwwApache服务器主目录practise例程.php:6:int 60

D:wampServerwwwApache服务器主目录practise例程.php:8:string 'A' (length=1)

4. array_sum() 函数

程序：

<?php
$scores = array(70, 80, 90, 60);
$grades1 = array('1A', '2B', '3C', '4D');
$grades2 = array('A1', 'B2', 'C3', '4D');
$sumScores = array_sum($scores);
$sumGrades1 = array_sum($grades1);
$sumGrades2 = array_sum($grades2);
var_dump($sumScores);   //int 300
echo "<br/>";
var_dump($sumGrades1);   //int 10
echo "<br/>";
var_dump($sumGrades2);   //int 4    //字符串开头不是数字不会被转换为整数或浮点数
?>

输出：

D:wampServerwwwApache服务器主目录practise例程.php:8:int 300

D:wampServerwwwApache服务器主目录practise例程.php:10:int 10

D:wampServerwwwApache服务器主目录practise例程.php:12:int 4

 

5. array_product() 函数

 程序：

<?php
$scores = array(70, 80, 90, 60);
$grades = array('1A', '2B', '3C', '4D');
$productScores = array_product($scores);
$productGrades = array_product($grades);
var_dump($productScores);   //int 30240000
echo "<br/>";
var_dump($productGrades);   //int 24
?>

 输出：

D:wampServerwwwApache服务器主目录practise例程.php:6:int 30240000

D:wampServerwwwApache服务器主目录practise例程.php:8:int 24

6. array_count_values() 函数

程序：

<?php
$array = array(1, "hello", 1, "world", "hello");
print_r( array_count_values($array) );
?>

输出：

Array ( [1] => 2 [hello] => 2 [world] => 1 )

数组的遍历

使用数组统计 count() 函数 和 for 循环语句可以遍历连续整数 “键” 的数组。

程序：

<?php
$chars = range('a','d');
$counts = count($chars);
for($key=0; $key<$counts; $key++){
    echo $chars[$key]."<br/>";
}
?>

输出：

a
b
c
d