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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： 欧洲色综合精品 | 午夜国产福利 | 婷婷综合久久 | 久久久久一| 福利视频一区二区 | 狠狠色丁香久久综合五月 | 伊人久久国产 | 精品国语对白精品自拍视 | 美妇乱人伦性 | 一区二区视频在线观看 | 一二三四视频社区在线中文 | 久久aa| 成人综合久久精品色婷婷 | 视频在线欧美 | www激情五月 | 国产午夜人做人免费视频中文 | 94久久国产乱子伦精品免费 | 欧美成人精品三级网站 | 中文字幕av一区二区三区 | 国产精品视频一区牛牛视频 | 日韩中文字幕精品一区在线 | 丁香六月婷婷七月激情 | 久草热在线观看 | 在线91色 | 婷婷综合五月中文字幕欧美 | 久久午夜青青草原影院 | 黄色视屏网站 | 91综合久久 | 免费无遮挡毛片 | 二级片毛片 | 日本综合欧美一区二区三区 | 亚洲天堂色网站 | 成年ssswww中国女人 | 中文激情 | 欧美人体xxxx | 色婷婷伊人 | 久久91精品国产91 | 精品久久久久久国产 | 国产成人综合91精品 | 一区二区三区影院 | 一道精品视频一区二区三区图片 |