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php讀寫二進制文件可以使用pack和unpack函數。
今天要處理一個二進制文件的問題，所以需要用一下，特意了解一下pack的用法，unpack用法與此類似。
簡單來說，pack函數就是給一個目標格式，和相應的參數，就可以返回二進制數據了。
下面舉例加以說明，對于四個整數：
pack("L4", 0,1,2,3)pack("LLLL", 0,1,2,3)pack("L", 0).pack("L", 1).pack("L", 2).pack("L", 3)上面的處理結果是一樣的，也就是說，format是描述后面的數據的格式。
至于具體format可以用什么，看看format characters就知道了。
比如一個30字符的 pack("a30", "http://www.jb51.NET") ，就是這個意思，很簡單
pack函數的官方聲明如下：
引用pack(php 3, php 4, php 5)pack -- Pack data into binary stringDescriptionstring pack ( string format [, mixed args [, mixed ...]] )Pack given arguments into binary string according to format. Returns binary string containing data. The idea to this function was taken from Perl and all formatting codes work the same as there, however, there are some formatting codes that are missing such as Perl's "u" format code. The format string consists of format codes followed by an optional repeater argument. The repeater argument can be either an integer value or * for repeating to the end of the input data. For a, A, h, H the repeat count specifies how many characters of one data argument are taken, for @ it is the absolute position where to put the next data, for everything else the repeat count specifies how many data arguments are consumed and packed into the resulting binary string. Currently implemented are表格 1. pack() format charactersCode Description a NUL-padded string A SPACE-padded string h Hex string, low nibble first H Hex string, high nibble first c signed char C unsigned char s signed short (always 16 bit, machine byte order) S unsigned short (always 16 bit, machine byte order) n unsigned short (always 16 bit, big endian byte order) v unsigned short (always 16 bit, little endian byte order) i signed integer (machine dependent size and byte order) I unsigned integer (machine dependent size and byte order) l signed long (always 32 bit, machine byte order) L unsigned long (always 32 bit, machine byte order) N unsigned long (always 32 bit, big endian byte order) V unsigned long (always 32 bit, little endian byte order) f float (machine dependent size and representation) d double (machine dependent size and representation) x NUL byte X Back up one byte @ NUL-fill to absolute position
看累了英文，下面來看看對應的中文解釋：
引用pack()函數的作用是：將數據壓縮成一個二進制字符串。a - NUL-padded string a - NUL- 字符串填滿[padded string] A - SPACE-padded string A - SPACE- 字符串填滿[padded string] h - Hex string, low nibble first h 主站蜘蛛池模板： 亚洲精品视频观看 | 久久久免费电影 | 国产在线观看一区二区 | 精品福利在线视频 | 五月综合激情婷婷 | 黄色一级大片在线免费看产 | 欧州一区 | 国产免费观看视频 | www免费视频 | 99精品久久久久久久 | 国产精品a级 | 美女天天干 | 亚洲国产精品久久久久 | 国产精品一区二区欧美黑人喷潮水 | 国产精品成人一区二区三区夜夜夜 | 巨大荫蒂视频欧美另类大 | 国内精品久久久久久 | 国产一区亚洲二区三区 | 福利社午夜影院 | 一本一道久久a久久精品综合蜜臀 | 亚洲精品久久久久久久久久久久久 | 日韩一级精品视频在线观看 | 天天色官网 | 午夜久草 | 久久夜夜| 欧美性受xxx | 视频在线观看亚洲 | 91成人在线视频 | 国产亚洲一区二区精品 | 久久久一区二区三区 | 久久久成人精品 | 久久夜视频 | 国产特一级黄色片 | 嫩呦国产一区二区三区av | 国产国产精品久久久久 | 999久久久久久久 | av男人的天堂在线 | 九九久久久 | 嫩草黄色影院 | 四色永久 | 日韩国产一区二区三区 |