定義和用法

pack() 函數(shù)把數(shù)據(jù)裝入一個(gè)二進(jìn)制字符串。

語法

pack(format,args+)

參數(shù)	描述
format	必需。規(guī)定在包裝數(shù)據(jù)時(shí)所使用的格式。
args+	可選。規(guī)定被包裝的一個(gè)或多個(gè)參數(shù)。

format 參數(shù)的可能值：

• 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

例子

例子 1

<?php
echo pack("C3",80,72,80);
?>

輸出：

PHP

例子 2

<?php
echo pack("C*",80,72,80);
?>

輸出：

PHP