A detailed description of the Ord ($STR) >0x80 in PHP _php tutorial

The encoding of the GBK simplified character set is expressed in 1 bytes and 2 bytes at a time. When the high is 0x00~0x7f, it is a byte, and the high position is more than 0x80 with 2 bytes "

Note: The brackets are all 2 binary

When you find that the content of a byte is greater than 0x7f, then it must be a (with another byte pieced together into a) Chinese characters, how to judge certainly greater than 0x7f?
0x7f (1111111) The next number is 0x80 (10000000), so want to be greater than 0x7f, the highest bit of this byte is certainly 1, we just need to determine whether the highest level is 1 on the line.

Judging Method:

Bit and (the same bit is 1 for 1, otherwise 0):
such as: To determine whether the third digit of a number is 1, as long as the 4 (100) and the number of the 2nd bit to determine whether 1 is 2 (10) bit with.
In the same vein, whether the eighth digit is 1 to follow (10000000) is 0x80.

Why not use >0x7f,php here may be OK, but in other strongly typed languages, the highest bits of 1 bytes are used to indicate negative numbers, a negative number must not be greater than 0x7f (the largest integer)

Let me give you an example:
A's Assic code is 97 (1100001)
A's Assic code is 65 (1000001)

b The Assic code is 98 (1100010)
b The Assic code is 66 (1000010)

Find a rule: a A-Z letter, as long as the lowercase letter, the sixth bit is definitely 1, we can use this to determine the case:
This time just with a letter with 0x20 (100000) to the position and judgment:
Copy CodeThe code is as follows:
if (ord ($a) &0x20) {
Capital
}

How do I change all the letters to uppercase? The sixth bit of 1 is changed to 0 on the line:
Copy CodeThe code is as follows:
$a = ' a ';
$a = Chr (ord ($a) & (~0x20));
echo $a;

http://www.bkjia.com/PHPjc/325958.html www.bkjia.com true http://www.bkjia.com/PHPjc/325958.html techarticle The encoding of the GBK simplified character set is expressed in 1 bytes and 2 bytes at a time. When the high is 0x00~0x7f, it is a byte, the high level is above 0x80 with 2 bytes to denote "Note: Inside the parentheses ...

