|
|
php讀寫(xiě)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(lèi)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?zhuān)?/p>
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： 手机在线看黄色 | 亚洲国产一区在线 | 91免费网| 五月婷婷激情综合网 | 亚洲国产精品激情在线观看 | 欧美xx在线观看 | 成年网站视频在线观看 | 久久综合香蕉久久久久久久 | 91亚洲精品色午夜麻豆 | 九九大香尹人视频免费 | 日韩中文字幕精品久久 | 在线成人爽a毛片免费软件 在线成人小视频 | 色综合久久88色综合天天提莫 | 亚洲图片校园另激情类小说 | 成人在线视频免费观看 | 四虎影视国产884a精品亚洲 | 国产91一区二区在线播放不卡 | 久久伊人热精品老鸭窝 | 午夜毛片网站 | 国产成人资源 | 97国产精品人人爽人人做 | 天天做天天玩天天爽天天 | 丁香花五月婷婷开心 | 五月婷婷在线视频 | 五月天婷婷激情视频 | 国产三级网| 中文字幕一区视频一线 | 在线免费福利 | 91免费版在线观看 | 蜜桃嫩草| 国产精品欧美日韩视频一区 | 巨大巨粗巨长 黑人长吊视频 | 亚洲激情图片 | 77se77亚洲欧美在线大屁股 | 亚洲第一香蕉视频 | 久久久久青草大香线综合精品 | 午夜视频福利在线观看 | 国产美女在线精品免费观看 | 欧美黑人两根巨大挤入 | 亚欧成人乱码一区二区 | 99在线国产视频 |