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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： av毛片在线播放 | 亚洲成人自拍 | 亚洲综合中文字幕在线观看 | 精品国产一区久久 | 黄色大片在线 | 国产美女一区二区三区 | 日韩欧美网 | 日本爱爱视频 | 毛片99| 欧美国产日韩精品 | 国产精品国产a | 欧美中文字幕一区二区 | 成年人黄色小视频 | 国产三级一区二区 | 国产一区二区在线播放 | 国产9 9在线 | 中文 | 欧美一级久久 | 国产精品视频网址 | 手机在线观看 | 美女张开腿露出尿口 | 久久精品色欧美aⅴ一区二区 | 国产精品片| 日韩一级免费大片 | 国产午夜精品一区二区三区嫩草 | 国产精品久久久 | av色站 | 成人三级av| 久久88 | 91av在线免费 | 久久亚洲一区 | 久久久美女 | 国产成人精品视频 | 国产精品美女久久久久久免费 | 亚洲国产成人在线视频 | 日韩av一区二区在线观看 | 亚洲在线一区二区 | 九九热免费视频在线观看 | 久久999| 欧美成人二区 | 中文字幕亚洲国产 | 日韩欧美三区 |