PHP built-in functions:

addcslashes — Add backslash escape characters to some characters in the string
addslashes — Escape characters in the string in a specified way
bin2hex — Convert binary data into Hexadecimal representation
chop — Alias ??function of rtrim()
chr — Returns the ASCII code of a character
chunk_split — Splits a string into small pieces according to a certain character length
convert_cyr_string — Converts Cyrillic characters to other characters
convert_uudecode — Decrypt a string
convert_uuencode — Encrypt a string
count_chars — Return character usage information in a string
crc32 — Calculate the crc32 polynomial of a string
crypt — One-way hash encryption function
echo — Used to Display some content
fprintf — Return the data as required and write it directly to the document stream
get_html_translation_table — Return an HTML entity that can be converted
hebrev — Convert a Hebrew-encoded string to visual text
hebrevc — Convert Hebrew-encoded Convert a string into visual text
html_entity_decode — The inverse function of the htmlentities () function, convert HTML entities into characters
htmlentities — Convert some characters in the string into HTML entities
htmlspecialchars_decode — The inverse function of htmlspecialchars() function, convert Convert HTML entities to characters
htmlspecialchars — Convert some characters in a string to HTML entities

explode — Convert a string into an array using delimiters

implode — Convert an array into a string using a specific delimiter
join — Convert an array into a string, alias of the implode() function
levenshtein — Calculate the difference between two words
localeconv — Get number-related format definitions
ltrim — Remove the blanks or specified characters on the left side of the string
md5_file — Encrypt a file with the MD5 algorithm
md5 — Encrypt a string with the MD5 algorithm
metaphone — Determine the pronunciation rules of a string
money_format — According to the parameters Formatted output of numbers
nl_langinfo — Query language and local information
nl2br — Replace the newline character "n" in the string with "
"
number_format — Formatted output of numbers according to parameters
ord — Replace an ASCII Convert the code into a character
parse_str — Convert a string in a certain format into a variable and value
print — Used to output a single value
printf — Display the data as required
quoted_printable_decode — Encrypt a string into an 8-bit Binary string
quotemeta — Escape several specific characters
rtrim — Remove the blanks or specified characters on the right side of the string
setlocale — Set local formats for numbers, dates, etc.
sha1_file — SHA1 a file Algorithm encryption
sha1 — Encrypt a string with SHA1 algorithm
similar_text — Compare two strings and return the number of similar characters considered by the system
soundex — Determine the pronunciation rules of a string
sprintf — Return the data as required, But it does not output
sscanf — can format strings
str_ireplace — matches and replaces strings like the str_replace() function, but is not case-sensitive
str_pad — pads both sides of the string
str_repeat — strings Perform repeated combinations
str_replace — Match and replace strings
str_rot13 — Encrypt the string with ROT13
str_shuffle — Randomly sort the characters in a string
str_split — Split a string into an array according to the character spacing
str_word_count — Obtain English word information in a string
strcasecmp — Compare strings in size, case-insensitively
strchr — Return part of a string through comparison An alias of the strstr() function
strcmp — Compare strings in size
strcoll - Compare the size of strings according to local settings
strcspn - Return the value of the continuous non-matching length of characters
strip_tags - Remove the HTML and PHP code in a string
stripcslashes - Unescap the addcslashes() function escape processing String
stripos — Find and return the position of the first match, matching is case-insensitive
stripslashes — Unescaped addslashes() function escapes the processed string
stristr — Returns parts of a string by comparison, comparison Case-insensitive
strlen — Get the encoded length of a string
strnatcasecmp — Use natural sorting to compare strings, case-insensitive
strnatcmp — Use natural sorting to compare strings
strncasecmp — Right Compare the first N characters of a string, case-insensitive
strncmp — Compare the first N characters of a string
strpbrk — Return a part of a string by comparison
strpos — Find and return the first match The position
strrchr — Returns the part of a string by comparing from back to front
strrev — Arranges all the letters in the string in reverse order
strripos — Searches from back to front and returns the position of the first match, matches are indistinguishable Uppercase and lowercase
strrpos - Search from back to front and return the position of the first match
strspn - Match and return the value of the length of consecutive occurrences of characters
strstr - Return a part of a string by comparison
strtok - Use a specified number of characters To split the string
strtolower — Convert the string to lowercase
strtoupper — Convert the string to uppercase
strtr — Compare and replace the string
substr_compare — Compare the truncated string
substr_count — Count a certain character in the string The number of occurrences of the segment
substr_replace — Replace some characters in the string
substr — Truncate the string
trim — Remove the blanks or specified characters on both sides of the string
ucfirst — Replace the first letter of the given string Convert to uppercase
ucwords — Convert the first letter of each English word in the given string to uppercase
vfprintf — Return the data as required and write it directly to the document stream
vprintf — Display the data as required
vsprintf - Return data as required, but do not output
wordwrap - Split the string according to a certain character length

Custom function:

1, the function range() to quickly create an array

For example The range() function can quickly create a number array from 1 to 9:

<?php 
    $numbers=range(1,9); //用range直接創(chuàng)建1~9共9個(gè)數(shù)字組成的數(shù)組，以“1”開(kāi)始“9”結(jié)束。 
    echo $numbers[1]; //輸出創(chuàng)建的第二個(gè)數(shù)組值：2； echo $numbers[0];則輸入第一個(gè)值：0。 
?>

Of course, using range(9,1) creates a number array from 9 to 1. At the same time, range() can also create a character array from a to z:

<?php 
    $numbers=range(a,z); 
    foreach ($numbers as $mychrs) //遍歷$numbers數(shù)組，每次循環(huán)當(dāng)前單元值被賦給$mychrs 
    echo $mychrs." "; //output a b c d e f g h i j k l m n o p q r s t u v w x y z 
?>

//foreach是一種遍歷數(shù)組的簡(jiǎn)便方法，foreach 僅能用于數(shù)組，當(dāng)試圖將其用于其它數(shù)據(jù)類(lèi)型或者一個(gè)未初始化的變量時(shí)會(huì)產(chǎn)生錯(cuò)誤，它有兩種格式：

foreach (array_expression as $value) statementforeach (array_expression as $key => $value) statement
第一種格式遍歷給定的 array_expression 數(shù)組。每次循環(huán)中，當(dāng)前單元的值被賦給 $value 并且數(shù)組內(nèi)部的指針向前移一步（因此下一次循環(huán)中將會(huì)得到下一個(gè)單元）。第二種格式做同樣的事，只除了當(dāng)前單元的鍵名也會(huì)在每次循環(huán)中被賦給變量 $key


使用字符數(shù)組時(shí)注意大小寫(xiě)，比如range(A,z)和range(a,Z)是不一樣的。

range()函數(shù)還具有第三個(gè)參數(shù)，該參數(shù)的作用是設(shè)定步長(zhǎng)，比如range(1,9,3)創(chuàng)建的數(shù)組元素是：1、4、7

2，PHP中常規(guī)數(shù)組的排序

一般數(shù)組中的各元素均以字符或數(shù)字表現(xiàn)的，所以可對(duì)數(shù)組元素進(jìn)行升序排列，該功能函數(shù)為sort()。比如：

<?php 
    $people=array(&#39;name&#39;,&#39;sex&#39;,&#39;nation&#39;,&#39;birth&#39;); 
    foreach ($people as $mychrs) 
        echo $mychrs." "; 
    sort($people); 
    echo "---排序后---"; 
    foreach ($people as $mychrs) 
        echo $mychrs." "; 
?>

升序排序后的數(shù)組元素顯示為 birth name nation sex，當(dāng)然，sort()函數(shù)是區(qū)分字母大小寫(xiě)的（字母從大到小的順序是：A…Z…a…z）

Sort()函數(shù)還具有第二參數(shù)，用來(lái)說(shuō)明升序的規(guī)則是用來(lái)比較數(shù)字還是字符串的。比如：

<?php 
    echo "---按數(shù)字升序排序---
    "; 
    $num2=array(&#39;26&#39;,&#39;3&#39;,); 
    sort($num2,SORT_NUMERIC); 
    foreach ($num2 as $mychrs) 
    echo $mychrs." "; 
    echo "
    ---按字符升序排序---
    "; 
    $num3=array(&#39;26&#39;,&#39;3&#39;); 
    sort($num3,SORT_STRING); 
    foreach ($num3 as $mychrs) 
    echo $mychrs." "; 
?>

SORT_NUMERIC和SORT_STRING用來(lái)聲明按數(shù)字或字符的升序排列。如果按照數(shù)字升序排列是：3，26；但如果按照字符升序排列則是：26，3了。

PHP中除了升序函數(shù)以外，還有降序或稱(chēng)反向排列的函數(shù)，就是rsort()函數(shù)，比如：

$num1=range(1,9);
rsort($num1); //這里其實(shí)就相當(dāng)于range(9,1)

3，PHP中關(guān)聯(lián)數(shù)組的排序

PHP除了支持?jǐn)?shù)字索引數(shù)組以外，還支持相關(guān)數(shù)組。比如如下數(shù)組就是一個(gè)相關(guān)(關(guān)聯(lián))數(shù)組：

$peoples=array('xm'=>'name','xb'=>'sex','mz'=>'nation','cs'=>'birth');

使用sort($peoples)默認(rèn)即是按照元素定義值的升序排序，在關(guān)聯(lián)數(shù)組中可使用asort()函數(shù)表示按元素值升序排序，關(guān)聯(lián)數(shù)組中最主要的則是可按照關(guān)鍵字（如xm、xb、mz等）的升序排序，該方法是用函數(shù)ksort()函數(shù)。

<?php 
    $peoples=array(&#39;xm&#39;=>&#39;name&#39;,&#39;xb&#39;=>&#39;sex&#39;,&#39;mz&#39;=>&#39;nation&#39;,&#39;cs&#39;=>&#39;birth&#39;); 
    foreach ($peoples as $mychrs) 
    echo $mychrs." "; 
    echo "
    --按元素值升序排列--
    "; 
    asort($peoples); 
    foreach ($peoples as $mychrs) 
    echo $mychrs." "; 
    echo "
    --按關(guān)鍵字升序排列--
    "; 
    ksort($peoples); 
    foreach ($peoples as $mychrs) 
    echo $mychrs." "; 
?>

和常規(guī)數(shù)組擁有sort()升序函數(shù)的反向排序rsort()降序函數(shù)相對(duì)應(yīng)的，關(guān)聯(lián)數(shù)組也有對(duì)應(yīng)的降序函數(shù)：asort()函數(shù)和arsort()函數(shù)、ksort()函數(shù)和krsort()函數(shù)。
記憶：原型函數(shù)是sort()，其中a、k表示關(guān)聯(lián)數(shù)組相關(guān)必須前置，反向排序使用r修飾。

4，PHP數(shù)組元素隨機(jī)排序

PHP中使用shuffle()函數(shù)將數(shù)組元素進(jìn)行隨機(jī)的重新排序，每次都會(huì)顯示不同的排序組合，比如：

<?php 
    $fer=array(&#39;cnbruce&#39;,&#39;cnrose&#39;,&#39;cnjames&#39;,&#39;cnanne&#39;); 
    shuffle($fer); //隨即排序，每刷新一次頁(yè)面則進(jìn)行一次隨機(jī)排序。 
    foreach ($fer as $mychrs) 
    echo $mychrs." "; 
?>

5，PHP數(shù)組按原順序反向排序

PHP中可使用array_reverse()函數(shù)將數(shù)組元素按原順序反向排序。比如：

<?php 
$fer=array(&#39;cnbruce&#39;,&#39;cnrose&#39;,&#39;cnjames&#39;,&#39;cnanne&#39;); 
foreach ($fer as $mychrs) 
echo $mychrs." "; 
$fer=array_reverse($fer); //將數(shù)組內(nèi)元素按原順序反向排序 
echo "--按原順序反向--"; 
foreach ($fer as $mychrs) 
echo $mychrs." "; 
?>