PHP中的关联数组详细介绍

关联数组用于存储键值对。例如, 要将学生不同学科的分数存储在一个数组中, 数字索引数组将不是最佳选择。取而代之的是, 我们可以使用相应主题的名称作为关联数组中的键, 而值将是它们各自获得的标记。
例子：
【PHP中的关联数组详细介绍】这里
array()
函数用于创建关联数组。

< ?php /* First method to create an associate array. */ $student_one = array ( "Maths" => 95, "Physics" => 90, "Chemistry" => 96, "English" => 93, "Computer" => 98); /* Second method to create an associate array. */ $student_two [ "Maths" ] = 95; $student_two [ "Physics" ] = 90; $student_two [ "Chemistry" ] = 96; $student_two [ "English" ] = 93; $student_two [ "Computer" ] = 98; /* Accessing the elements directly */ echo "Marks for student one is:\n" ; echo "Maths:" . $student_two [ "Maths" ], "\n" ; echo "Physics:" . $student_two [ "Physics" ], "\n" ; echo "Chemistry:" . $student_two [ "Chemistry" ], "\n" ; echo "English:" . $student_one [ "English" ], "\n" ; echo "Computer:" . $student_one [ "Computer" ], "\n" ; ?>

输出如下：

Marks for student one is:Maths:95Physics:90Chemistry:96English:93Computer:98

遍历关联数组：
我们可以使用循环遍历关联数组。我们可以通过两种方式遍历关联数组。首先通过使用
对于
循环, 其次使用
前言
.
例子：
这里
array_keys()
函数用于查找赋予它们的索引名称, 以及
计数()
函数用于对关联数组中的索引数进行计数。

< ?php /* Creating an associative array */ $student_one = array ( "Maths" => 95, "Physics" => 90, "Chemistry" => 96, "English" => 93, "Computer" => 98); /* Looping through an array using foreach */ echo "Looping using foreach: \n" ; foreach ( $student_one as $subject => $marks ){ echo "Student one got " . $marks . " in " . $subject . "\n" ; } /* Looping through an array using for */ echo "\nLooping using for: \n" ; $subject = array_keys ( $student_one ); $marks = count ( $student_one ); for ( $i =0; $i < $marks ; ++ $i ) { echo $subject [ $i ] . ' ' . $student_one [ $subject [ $i ]] . "\n" ; } ?>

输出如下：

Looping using foreach: Student one got 95 in MathsStudent one got 90 in PhysicsStudent one got 96 in ChemistryStudent one got 93 in EnglishStudent one got 98 in ComputerLooping using for: Maths 95Physics 90Chemistry 96English 93Computer 98

创建混合类型的关联数组

< ?php /* Creating an associative array of mixed types */ $arr [ "xyz" ] = 95; $arr [100] = "abc" ; $arr [11.25] = 100; $arr [ "abc" ] = "pqr" ; /* Looping through an array using foreach */ foreach ( $arr as $key => $val ){ echo $key . "==> " . $val . "\n" ; } ?>

输出如下：