字符串
strlen --- 获取字符串长度
php
<?php
$str = 'abcdef';
echo strlen($str); // 6
$str = ' ab cd ';
echo strlen($str); // 7
//strlen() 返回的是字符串的字节数，而不是其中字符的数量。
?>strpos --- 查找字符串首次出现的位置
php
$mystring = 'abc';
$findme = 'a';
$pos = strpos($mystring, $findme);
echo $pos; //0
// 忽视位置偏移量之前的字符进行查找
$newstring = 'abcdef abcdef';
$pos = strpos($newstring, 'a', 1); // $pos = 7, 不是 0
echo $pos; //7str_replace --- 子字符串替换
php
$bodytag = str_replace("%body%", "black", "<body text='%body%'>");
echo $bodytag; //<body text='black'>
$vowels = array("a", "e", "i", "o", "u", "A", "E", "I", "O", "U");
$onlyconsonants = str_replace($vowels, "", "Hello World of PHP");
echo $onlyconsonants; //Hll Wrld f PHP
$phrase = "You should eat fruits, vegetables, and fiber every day.";
$healthy = array("fruits", "vegetables", "fiber");
$yummy = array("pizza", "beer", "ice cream");
$newphrase = str_replace($healthy, $yummy, $phrase);
echo $newphrase; //You should eat pizza, beer, and ice cream every day.
$str = str_replace("ll", "", "good golly miss molly!", $count);
echo $count;//2
$str = "Line 1\nLine 2\rLine 3\r\nLine 4\n";
$order = array("\r\n", "\n", "\r");
$replace = '<br />';
$newstr = str_replace($order, $replace, $str);
echo $newstr;//Line 1<br />Line 2<br />Line 3<br />Line 4<br />
// 输出 F ，因为 A 被 B 替换，B 又被 C 替换，以此类推...
// 由于从左到右依次替换，最终 E 被 F 替换
$search = array('A', 'B', 'C', 'D', 'E');
$replace = array('B', 'C', 'D', 'E', 'F');
$subject = 'A';
echo str_replace($search, $replace, $subject);//F
$letters = array('a', 'p');
$fruit = array('apple', 'pear');
$text = 'a p';
$output = str_replace($letters, $fruit, $text);
echo $output; //apearpearle pear数组
count --- 统计数组、Countable 对象中所有元素的数量
php
<?php
$a[0] = 1;
$a[1] = 3;
$a[2] = 5;
var_dump(count($a));//int(3)
$b[0] = 7;
$b[5] = 9;
$b[10] = 11;
var_dump(count($b));//int(3)
?>
<?php
$food = array('fruits' => array('orange', 'banana', 'apple'),
'veggie' => array('carrot', 'collard', 'pea'));
// 递归计数
var_dump(count($food, COUNT_RECURSIVE)); //int(8)
// 常规计数
var_dump(count($food)); //int(2)
?>explode --- 使用一个字符串分割另一个字符串（字符串转数组）
php
<?php
// 示例 1
$pizza = "piece1 piece2 piece3 piece4 piece5 piece6";
$pieces = explode(" ", $pizza);
echo $pieces[0]; // piece1
echo $pieces[1]; // piece2
// 示例 2
$data = "foo:*:1023:1000::/home/foo:/bin/sh";
list($user, $pass, $uid, $gid, $gecos, $home, $shell) = explode(":", $data);
echo $user; // foo
echo $pass; // *
/*
字符串内不包含分隔字符时，
会简单返回只有一个原始字符串元素的 array。
*/
$input1 = "hello";
$input2 = "hello,there";
$input3 = ',';
var_dump( explode( ',', $input1 ) );
var_dump( explode( ',', $input2 ) );
var_dump( explode( ',', $input3 ) );
$str = 'one|two|three|four';
// 正数的 limit
print_r(explode('|', $str, 1)); //Array([0] => one|two|three|four)
print_r(explode('|', $str, 2)); //Array([0] => one [1] => two|three|four)
// 负数的 limit
print_r(explode('|', $str, -1)); //Array([0] => one [1] => two [2] => three)
print_r(explode('|', $str, -2)); //Array([0] => one [1] => two)
?>implode --- 用字符串连接数组元素(数组转字符串)
php
<?php
$array = ['lastname', 'email', 'phone'];
var_dump(implode(",", $array)); // string(20) "lastname,email,phone"
// Empty string when using an empty array:
var_dump(implode('hello', [])); // string(0) ""
// The separator is optional:
var_dump(implode(['a', 'b', 'c'])); // string(3) "abc"
$elements = array('a', 'b', 'c');
echo "<ul><li>" . implode("</li><li>", $elements) . "</li></ul>"; //<ul><li>a</li><li>b</li><li>c</li></ul>
?>in_array --- 检查数组中是否存在某个值
php
<?php
$os = array("Mac", "NT", "Irix", "Linux");
//区分大小写例子
if (in_array("Irix", $os)) {
echo "Got Irix"; //Got Irix
}
if (in_array("mac", $os)) {
echo "Got mac";
}
//严格类型检查例子
$a = array('1.10', 12.4, 1.13);
if (in_array('12.4', $a, true)) {
echo "'12.4' found with strict check\n";
}
if (in_array(1.13, $a, true)) {
echo "1.13 found with strict check\n"; //1.13 found with strict check
}
//数组
$a = [['p', 'h'], ['p', 'r'], 'o'];
if (in_array(['p', 'h'], $a)) {
echo "'ph' was found\n"; //'ph' was found
}
if (in_array(['f', 'i'], $a)) {
echo "'fi' was found\n";
}
if (in_array('o', $a)) {
echo "'o' was found\n"; //'o' was found
}
?>array_key_exists --- 检查数组里是否有指定的键名或索引
php
$search_array = ['first' => 1, 'second' => 4];
if (array_key_exists('first', $search_array)) {
echo "The 'first' element is in the array"; //The 'first' element is in the array
}array_key_exists() 与 isset() 的对比
isset() 对于数组中为 null 的值不会返回 true，而 array_key_exists() 会。
php
<?php
$search_array = array('first' => null, 'second' => 4);
// 返回 true
array_key_exists('first', $search_array); //true
// 返回 false
isset($search_array['first']); //false
?>array_column --- 返回输入数组中指定列的值
php
// 表示从数据库返回的记录集的数组
$records = [
[
'id' => 2135,
'first_name' => 'John',
'last_name' => 'Doe',
],
[
'id' => 3245,
'first_name' => 'Sally',
'last_name' => 'Smith',
],
[
'id' => 5342,
'first_name' => 'Jane',
'last_name' => 'Jones',
],
[
'id' => 5623,
'first_name' => 'Peter',
'last_name' => 'Doe',
]
);
$first_names = array_column($records, 'first_name');
print_r($first_names); /*Array(
[0] => John
[1] => Sally
[2] => Jane
[3] => Peter )*/
//从结果集中总取出 last_name 列，用相应的"id"作为键值
// 使用示例 #1 中的 $records 数组
$last_names = array_column($records, 'last_name', 'id');
print_r($last_names); /*Array
(
[2135] => Doe
[3245] => Smith
[5342] => Jones
[5623] => Doe
)*/
$first_names = array_column($records, null, 'id');
print_r($last_names); /*Array
(
[2135] => Array
(
[id] => 2135
[first_name] => John
[last_name] => Doe
)
[3245] => Array
(
[id] => 3245
[first_name] => Sally
[last_name] => Smith
)
[5342] => Array
(
[id] => 5342
[first_name] => Jane
[last_name] => Jones
)
[5623] => Array
(
[id] => 5623
[first_name] => Peter
[last_name] => Doe
)
)*/array_keys --- 返回数组中所有的键
php
$array = array("size" => "XL", "color" => "gold");
var_dump(array_keys($array)) //['size','color']array_values --- 返回数组中所有的值
php
<?php
$array = array("size" => "XL", "color" => "gold");
print_r(array_values($array)); /*Array
(
[0] => XL
[1] => gold
)*/
?>array_filter --- 使用回调函数过滤数组的元素
php
<?php
function odd($var)
{
// 返回输入整数是否为奇数（单数）
return $var & 1;
}
function even($var)
{
// 返回输入整数是否为偶数
return !($var & 1);
}
$array1 = ['a' => 1, 'b' => 2, 'c' => 3, 'd' => 4, 'e' => 5];
$array2 = [6, 7, 8, 9, 10, 11, 12];
echo "Odd :\n";
print_r(array_filter($array1, "odd"));
echo "Even:\n";
print_r(array_filter($array2, "even"));
$array3 = [1,'0', 0, false, null, '','fasle'];
print_r(array_filter($array3)); //[1, false]
?>array_merge --- 合并一个或多个数组
php
<?php
$array1 = array("color" => "red", 2, 4);
$array2 = array("a", "b", "color" => "green", "shape" => "trapezoid", 4);
$result = array_merge($array1, $array2);
print_r($result); /*
Array
(
[color] => green
[0] => 2
[1] => 4
[2] => a
[3] => b
[shape] => trapezoid
[4] => 4
)
*/
//如果你想完全保留原有数组并只想新的数组附加到后面，可以使用 + 运算符：
$array1 = array(0 => 'zero_a', 2 => 'two_a', 3 => 'three_a');
$array2 = array(1 => 'one_b', 3 => 'three_b', 4 => 'four_b');
$result = $array1 + $array2;
var_dump($result);/*
array(5) {
[0]=>
string(6) "zero_a"
[2]=>
string(5) "two_a"
[3]=>
string(7) "three_a"
[1]=>
string(5) "one_b"
[4]=>
string(6) "four_b"
}
*/
?>array_slice --- 从数组中取出一段
php
$input = array("a", "b", "c", "d", "e");
print_r(array_slice($input, 2)); // [c,d,e]
print_r(array_slice($input, -2, 1)); // [d]
print_r(array_slice($input, 0, 3)); // [a,b,c]
// 注意数组中 key 的不同
print_r(array_slice($input, 2, -1)); // [c,d]
print_r(array_slice($input, 2, -1, true)); // [c,d]
$ar = array('a'=>'apple', 'b'=>'banana', '42'=>'pear', 'd'=>'orange');
print_r(array_slice($ar, 0, 3));/*
Array
(
[a] => apple
[b] => banana
[0] => pear
)
*/
print_r(array_slice($ar, 0, 3, true));/*
Array
(
[a] => apple
[b] => banana
[42] => pear
)
*/