我们发现，如果使用echo或者print输出一个十六进制数，输出的结果会自动转换成十进制，例如

$hex = 0x3e24;
echo $hex;
print $hex;

这样会直接输出

我们使用进制转换工具可以知道3e24的十进制为15908

我们先来看看sprintf函数的用法，其中的format参数有提到x跟X格式的使用效果，x就是以小写十六进制输出内容，X则是以大写十六进制输出内容

sprintf

(PHP 4, PHP 5, PHP 7)

sprintf — Return a formatted string

说明

string sprintf    ( string $format   [, mixed $args   [, mixed $...  ]] )

Returns a string produced according to the formatting string   format.

参数

format

• x - the argument is treated as an integer          

   and presented as a hexadecimal number (with lowercase letters).

• X - the argument is treated as an integer            

  and presented as a hexadecimal number (with uppercase letters).

不过sprintf只是返回一串格式化后的字符串，并没有把它输出来，所有要结合echo使用，示例：

$hex = 0x3e24;
echo sprintf('这是一个十六进制数:%x', $hex);

输出结果为：这是一个十六进制数:3e24

当然我们可以使用printf更加简便地输出十六进制

printf

(PHP 4, PHP 5, PHP 7)

printf — 输出格式化字符串

说明

int printf    ( string $format   [, mixed $args   [, mixed $...  ]] )

依据 format 格式参数产生输出。

参数

• format

  format 描述信息，请参见 sprintf()。

• args

  
  

简化后的代码就是：

$hex = 0x3e24;
printf('这是一个十六进制数:%x', $hex);

附注：

• % - a literal percent character. No          

   argument is required.

• b - the argument is treated as an          

  integer, and presented as a binary number.

• c - the argument is treated as an          

  integer, and presented as the character with that ASCII value.

• d - the argument is treated as an            

  integer, and presented as a (signed) decimal number.

• e - the argument is treated as scientific            

  notation (e.g. 1.2e+2). The precision specifier stands for the number of digits after the            decimal point since PHP 5.2.1. In earlier versions, it was taken as number of significant digits (one less).

• E - like %e but uses uppercase letter (e.g. 1.2E+2).

• f - the argument is treated as a float, and presented as a floating-point number (locale aware).

• F - the argument is treated as a float, and presented as a floating-point number (non-locale aware). Available since PHP 5.0.3.

• g - shorter of %e and  %f.

• G - shorter of %E and %f.

• o - the argument is treated as an integer, and presented as an octal number.

• s - the argument is treated as and presented as a string.

• u - the argument is treated as an integer, and presented as an unsigned decimal number.

来自ansion

2017-3-21