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php讀寫二進制文件可以使用pack和unpack函數(shù)。
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(shù)就是給一個目標(biāo)格式，和相應(yīng)的參數(shù)，就可以返回二進制數(shù)據(jù)了。
下面舉例加以說明，對于四個整數(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，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30字符的 pack("a30", "http://www.jb51.NET") ，就是這個意思，很簡單
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，下面來看看對應(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： 91天堂97年嫩模在线观看 | 成人欧美视频在线观看 | 欧美在线看欧美高清视频免费 | 美女张开腿让男人桶爽免费看 | 国产精品一区二区三 | 日韩精品永久免费播放平台 | 久久精品伊人 | 黄 在线| 91在线视频福利 | 久久久久精彩视频 | 精品久久久久国产 | 国产剧情在线视频 | 在线观看国产小视频 | 午夜小视频免费观看 | 国产精品午夜免费观看网站 | 2021国产精品一区二区在线 | 国内精品国语自产拍在线观看91 | 乱色欧美videos黑人 | 天天天操天天天干 | 成人激情综合 | 91成人影院未满十八勿入 | 欧美性巨大 | 免费黄色高清视频 | 色资源在线 | 婷婷综合另类小说色区 | 色草在线| 国语自产免费精品视频在 | 亚洲国产精品婷婷久久久久 | 日本人乱人乱亲乱色视频观看 | 激情文学88| 德国女人一级毛片免费 | 国产激情在线视频 | 欧美精品午夜 | 91麻豆精品国产91久久久 | 天天插天天爽 | 亚洲免费中文 | 国产剧情自拍 | 伊人国产视频 | 久久永久视频 | 欧美三级视频 | 亚洲综合在线成人一区 |