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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： 亚洲精品一区二区三区在线 | 精品国产乱码久久久久久牛牛 | 一本大道久久a久久精二百 欧洲一区二区三区 | 日韩精品一区在线观看 | 成人国产精品久久 | 国产成人精品一区二 | av影音资源 | 午夜精品久久久久久久久久久久 | 午夜免费网站 | 免费在线毛片 | 日韩av.com | 国产一区二区在线免费 | 91免费看片 | 九九看片| 一级黄色生活视频 | 亚洲+变态+欧美+另类+精品 | 玩丰满女领导对白露脸hd | 国产精品亚洲一区二区三区在线 | 国产精品乱码一区二区三区 | 成人精品一区 | 久久国产综合 | 成人精品在线观看 | 国产一级成人 | 久久国产精品视频观看 | 一区日韩| 久久高清精品 | 美女黄网| 亚洲一级黄色 | 国产精品视频一二三区 | 成人午夜黄色 | 国产精品久久久久久久久图文区 | 亚洲欧美在线观看 | 91国自视频 | 久在线观看 | 亚洲人成人一区二区在线观看 | www.日本精品| 一区二区三区四区国产 | 国产精品 亚洲一区 | 国内久久 | 一本大道久久a久久精二百 国产成人免费在线 | 在线欧美亚洲 |