php数组总结篇(一）

数组 1.数组的下标是整型数值或者是字符串类型。 eg1．索引数组的键是______，关联数组的键是______。 2.字符串作为索引的时候，应加上引号。常量或者变量不用加引号，否则无法编译。 在php中，没有引号的字符串会自动生成一个裸字符串，而 PHP 可能会在以后定义此常量，不幸的是你的代码中有同样的名字，那么这个字符串就被重新赋值。 eg2.<?php // 显示所有错误 error_reporting(E_ALL); $arr = array('fruit' => 'apple', 'veggie' => 'carrot'); // 正确 print $arr['fruit']; // apple print $arr['veggie']; // carrot // 不正确。This works but also throws a PHP error of // level E_NOTICE because of an undefined constant named fruit // // Notice: Use of undefined constant fruit - assumed 'fruit' in... print $arr[fruit]; // apple // Let's define a constant to demonstrate what's going on. We // will assign value 'veggie' to a constant named fruit. define('fruit','veggie'); // Notice the difference now print $arr['fruit']; // apple print $arr[fruit]; // carrot // The following is okay as it's inside a string. Constants are not // looked for within strings so no E_NOTICE error here print "Hello $arr[fruit]"; // Hello apple // With one exception, braces surrounding arrays within strings // allows constants to be looked for print "Hello {$arr[fruit]}"; // Hello carrot print "Hello {$arr['fruit']}"; // Hello apple // This will not work, results in a parse error such as: // Parse error: parse error, expecting T_STRING' or T_VARIABLE' or T_NUM_STRING' // This of course applies to using autoglobals in strings as well print "Hello $arr['fruit']"; print "Hello $_GET['foo']"; // Concatenation is another option print "Hello " . $arr['fruit']; // Hello apple ?> 3.键值问题 $a['color'] = 'red'; $a['taste'] = 'sweet'; $a['shape'] = 'round'; $a['name'] = 'apple'; $a[] = 4; // key will be 0 $b[] = 'a'; // key will be 0 $b[] = 'b'; // key will be 1 $b[] = 'c'; // key will be 2 switching = array( 10, // key = 0 5 => 6, 3 => 7, 'a' => 4, 11, // key = 6 (maximum of integer-indices was 5) '8' => 2, // key = 8 (integer!) '02' => 77, // key = '02' 0 => 12 // the value 10 will be overwritten by 12 ); <?php $multi_array = array("red", "green", 42 => "blue","yellow" => array("apple",9 => "pear","banana","orange" => array("dog","cat","iguana"))); ?> A．$multi_array['yellow']['apple'][0] B．$multi_array['blue'][0]['orange'][1] C．$multi_array[3][3][2] D．$multi_array['yellow']['orange']['cat'] E．$multi_array['yellow']['orange'][1] --------------------------------待续待续待续------ 4.array_walk 5.var_dump 6.array_intersect 7.array_sum 8.array_count_values 9.array_flip 10.natsort 11.ksort(),asort(),krsort(),sort(),usort() 12.array_reverse() 13.array_merge 14.reset -------------------------------待续待续待续------ 15.array_combine 16array_count_values 17.array_diff 18.array_filter 19.array_search


有用  |  无用 取消

猜你喜欢