PHP explains ASCII code comparison table and character conversion in detail

1. General ASCII code comparison table

Illustrated ASCII code comparison table , taking character A as an example
Dec represents decimal, such as 65
Hx represents hexadecimal, such as 41
Oct represents octal, such as 101
Char represents display character, such as A

The ASCII code comparison table is divided into two units
1, control characters 0-31 and 127
2, displayable characters 32-126
(1) 48～57 are the ten Arabic numerals from 0 to 9;
(2) 65～90 are 26 uppercase English letters;
(3) 97～122 are 26 lowercase English letters;
(4 ) Other punctuation marks, arithmetic symbols, etc.;

2. ASCII extension code comparison table

3. PHP character conversion function description

For specific character conversion function description, please refer to [PHP Functions Detailed Explanation of Decimal, Binary, and Octal] and hexadecimal conversion function description]
Decimal to binary decbin() function
Decimal to octal decoct() function
Decimal to hexadecimal dechex() function
Binary to hexadecimal Enter bin2hex() function
Binary to decimal to enter bindec() Function
Octal to decimal octdec() Function
Hexadecimal to decimal hexdec() function
Any base conversion base_convert() Function

Character conversion example
Example 1, how to convert a character to binary, octal or hexadecimal, you can Use the ord() function to first convert characters into ASCII values, and then use the corresponding base conversion function to convert, as follows
a This character is converted to its binary/octal/hexadecimal, as follows
a character Decimal: ord('a'); //Output 97
Binary: decbin(ord('a')); //Output 1100001
Octal: decoct(ord('a')); //Output 141
Hexadecimal: dechex(ord('a')); //Output 61

Then you can check the results of each decimal output against the ASCII code comparison table above.

Example 2, how to convert a binary to hexadecimal or decimal, such as the binary of a, as follows
Use the method of Example 1 to obtain the binary of a character
decbin(ord('a'));
Then convert binary to hexadecimal or decimal
Hex: bin2hex(decbin(ord('a')));//Output 31313030303031
Binary J: bindec(decbin(ord('a'))); //Output 97

The ord() function discussed above will be discussed in detail in the next issue of the Chinese character encoding research series.

Four, reference materials
PHP functions detailed explanation of decimal, binary, octal and hexadecimal conversion functions
php batch ascii to string
asciitable comparison table
Wikipedia ASCII
Baidu Encyclopedia ASCII

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