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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： 涩涩爱网站 | 91人成网站色www | 欧美特黄a级高清免费大片 欧美特黄a级高清免费看片 | 四色网站| 久草中文网 | 日本欧美一区二区免费视 | 麻豆91精品91久久久 | 久久精品久久久久久久久人 | 国产91一区二区在线播放不卡 | 91最新视频在线观看 | 精品国产香蕉在线播出 | 欧亚精品一区二区三区 | 国产一区自拍视频 | 美女张开腿让男人桶爽免费看 | 欧美a色| 国产高清视频免费最新在线 | 国产网红 | 国产精欧美一区二区三区 | 男女午夜性爽快免费视频不卡 | 91精品一区二区三区久久久久 | 91免费永久国产在线观看 | 中国精品视频一区二区三区 | 午夜在线视频国产 | 国产欧美日韩haodiaose | 国产真实伦视频在线视频 | 国产精品视频国产永久视频 | 91麻豆精品国产91久久久 | 在线91色 | 91精品国产乱码久久久久久 | 欧美成人免费大片888 | 国产情侣小视频 | 精品日本一区二区三区在线观看 | 亚洲春黄在线观看 | 激情婷婷综合 | 色在线播放 | 99久久精品国语对白 | 免费一级毛片不卡不收费 | 激情图片小说网 | 韩国精品一区二区久久 | 久久精品久久久久久久久人 | 久久久久久久综合日本亚洲 |