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php讀寫二進(jìn)制文件可以使用pack和unpack函數(shù)。
今天要處理一個(gè)二進(jìn)制文件的問(wèn)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(jiǎn)單來(lái)說(shuō)，pack函數(shù)就是給一個(gè)目標(biāo)格式，和相應(yīng)的參數(shù)，就可以返回二進(jìn)制數(shù)據(jù)了。
下面舉例加以說(shuō)明，對(duì)于四個(gè)整數(shù)：
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(jié)果是一樣的，也就是說(shuō)，format是描述后面的數(shù)據(jù)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(gè)30字符的 pack("a30", "http://www.jb51.NET") ，就是這個(gè)意思，很簡(jiǎn)單
pack函數(shù)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(lái)看看對(duì)應(yīng)的中文解釋：
引用pack()函數(shù)的作用是：將數(shù)據(jù)壓縮成一個(gè)二進(jìn)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： 伊人9 | 国产a久久精品一区二区三区 | 国产亚洲精品拍拍拍拍拍 | 国产不卡一区 | 香蕉草草久在视频在线播放 | 亚洲一区视频 | 99国产精品九九视频免费看 | 久久亚洲精品永久网站 | 色爱区综合激月婷婷激情五月 | 中文字幕色综合久久 | 91精品国产丝袜高跟鞋 | 国产精品免费视频播放 | 色老板视频在线 | 午夜国产福利在线观看 | 激情五月综合综合久久69 | 国产精品对白刺激 | 国产麻豆精品一区 | 国产 福利 在线 | 最新国产福利在线 | 亚洲人成依人成综合网 | 黄视频网站观看 | 久久看视频 | 亚洲一区综合在线播放 | 日韩一区二区三区视频 | 一二三四视频社区在线中文 | 怡红院成人在线 | 999精品视频在线 | 五月激情网站 | 91精品国产91久久 | 亚洲小说另类 | 拍真实国产伦偷精品 | 亚洲不卡一区二区三区 | 日本一区二区在线免费观看 | 69热视频在线观看免费自拍 | 日本精品久久久久久久 | 国产黄色片在线看 | 亚洲精品午夜级久久久久 | 国产精品免费观看网站 | 亚洲午夜精品久久久久久成年 | 国产精品视频一区二区三区w | 国产精品视频免费观看 |