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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： 2019伊人查蕉在线观看 | 国内极度色诱视频网站 | 床伴在线观看免费高清完整泰剧第四集 | 女人被弄到高潮叫床免 | 亚洲一区自拍高清亚洲精品 | 国产老师开裆丝袜喷水漫画 | 老太婆性BBWBBW | 久久久久国产一级毛片高清片 | 亚洲第一免费播放区 | 囯产精品久久久久久久久免费蜜桃 | 墨西哥美女主播 | 99久久亚洲 | 久久久久久久久久毛片精品美女 | 国产成人精品久久久久婷婷 | 欧美四虎精品二区免费 | se01短视频在线观看 | 女人高潮了拔出来了她什么感觉 | 乌克兰18性hd | 亚洲色综合中文字幕在线 | 内射气质御姐视频在线播放 | 大香伊蕉在人线国产最新 | 国产色精品久久人妻无码看片软件 | 轻点灬大ji巴太粗太双性高h | 色宅男午夜电影网站 | 青柠在线观看免费高清电视剧荣耀 | 欧美手机在线 | 欧美亚洲日韩欧洲不卡 | 边吃胸边膜下床震免费版视频 | 女人被躁到高潮嗷嗷叫69 | 久久er国产免费精品 | 久久中文电影 | 国产99r视频精品免费观看 | 欧美5g影院天天爽天天看 | 儿子你得太大了慢点插 | 女人张开腿让男人桶爽免 | 手机伊在人线香蕉2 | 野草视频在线观看 | 久久怡红院国产精品 | 精品无码一区二区三区不卡 | 999久久久国产精品蜜臀AV | 国产伦精品一区二区三区精品 |