計算機中的字符表示都是2進制,1B(字節)=8bit 用八個內存單元爲一個位標號(編碼),這是ASCII編碼 8bit用了7bit 2^7=128個 擴展的ASCII用了8bit 2^8=256個
256對漢字是遠遠不夠,代替漢字就要用多位表示,gb2312是2字節 utf8是3字節
1、ASCII表中的字符分 爲可打印與非打印字符
非打印字符 : 0-31 + 127
剩下的是可打印字符
ASCII碼錶
Bin | Dec | Hex | 縮寫/字符 | 解釋 |
00000000 | 0 | 00 | NUL(null) | 空字符 |
00000001 | 1 | 01 | SOH(start of headling) | 標題開始 |
00000010 | 2 | 02 | STX (start of text) | 正文開始 |
00000011 | 3 | 03 | ETX (end of text) | 正文結束 |
00000100 | 4 | 04 | EOT (end of transmission) | 傳輸結束 |
00000101 | 5 | 05 | ENQ (enquiry) | 請求 |
00000110 | 6 | 06 | ACK (acknowledge) | 收到通知 |
00000111 | 7 | 07 | BEL (bell) | 響鈴 |
00001000 | 8 | 08 | BS (backspace) | 退格 |
00001001 | 9 | 09 | HT (horizontal tab) | 水平製表符 |
00001010 | 10 | 0A | LF (NL line feed, new line) | 換行鍵 |
00001011 | 11 | 0B | VT (vertical tab) | 垂直製表符 |
00001100 | 12 | 0C | FF (NP form feed, new page) | 換頁鍵 |
00001101 | 13 | 0D | CR (carriage return) | 回車鍵 |
00001110 | 14 | 0E | SO (shift out) | 不用切換 |
00001111 | 15 | 0F | SI (shift in) | 啓用切換 |
00010000 | 16 | 10 | DLE (data link escape) | 數據鏈路轉義 |
00010001 | 17 | 11 | DC1 (device control 1) | 設備控制1 |
00010010 | 18 | 12 | DC2 (device control 2) | 設備控制2 |
00010011 | 19 | 13 | DC3 (device control 3) | 設備控制3 |
00010100 | 20 | 14 | DC4 (device control 4) | 設備控制4 |
00010101 | 21 | 15 | NAK (negative acknowledge) | 拒絕接收 |
00010110 | 22 | 16 | SYN (synchronous idle) | 同步空閒 |
00010111 | 23 | 17 | ETB (end of trans. block) | 傳輸塊結束 |
00011000 | 24 | 18 | CAN (cancel) | 取消 |
00011001 | 25 | 19 | EM (end of medium) | 介質中斷 |
00011010 | 26 | 1A | SUB (substitute) | 替補 |
00011011 | 27 | 1B | ESC (escape) | 溢出 |
00011100 | 28 | 1C | FS (file separator) | 文件分割符 |
00011101 | 29 | 1D | GS (group separator) | 分組符 |
00011110 | 30 | 1E | RS (record separator) | 記錄分離符 |
00011111 | 31 | 1F | US (unit separator) | 單元分隔符 |
00100000 | 32 | 20 | (space) | 空格 |
00100001 | 33 | 21 | ! | |
00100010 | 34 | 22 | " | |
00100011 | 35 | 23 | # | |
00100100 | 36 | 24 | $ | |
00100101 | 37 | 25 | % | |
00100110 | 38 | 26 | & | |
00100111 | 39 | 27 | ' | |
00101000 | 40 | 28 | ( | |
00101001 | 41 | 29 | ) | |
00101010 | 42 | 2A | * | |
00101011 | 43 | 2B | + | |
00101100 | 44 | 2C | , | |
00101101 | 45 | 2D | - | |
00101110 | 46 | 2E | . | |
00101111 | 47 | 2F | / | |
00110000 | 48 | 30 | 0 | |
00110001 | 49 | 31 | 1 | |
00110010 | 50 | 32 | 2 | |
00110011 | 51 | 33 | 3 | |
00110100 | 52 | 34 | 4 | |
00110101 | 53 | 35 | 5 | |
00110110 | 54 | 36 | 6 | |
00110111 | 55 | 37 | 7 | |
00111000 | 56 | 38 | 8 | |
00111001 | 57 | 39 | 9 | |
00111010 | 58 | 3A | : | |
00111011 | 59 | 3B | ; | |
00111100 | 60 | 3C | < | |
00111101 | 61 | 3D | = | |
00111110 | 62 | 3E | > | |
00111111 | 63 | 3F | ? | |
01000000 | 64 | 40 | @ | |
01000001 | 65 | 41 | A | |
01000010 | 66 | 42 | B | |
01000011 | 67 | 43 | C | |
01000100 | 68 | 44 | D | |
01000101 | 69 | 45 | E | |
01000110 | 70 | 46 | F | |
01000111 | 71 | 47 | G | |
01001000 | 72 | 48 | H | |
01001001 | 73 | 49 | I | |
01001010 | 74 | 4A | J | |
01001011 | 75 | 4B | K | |
01001100 | 76 | 4C | L | |
01001101 | 77 | 4D | M | |
01001110 | 78 | 4E | N | |
01001111 | 79 | 4F | O | |
01010000 | 80 | 50 | P | |
01010001 | 81 | 51 | Q | |
01010010 | 82 | 52 | R | |
01010011 | 83 | 53 | S | |
01010100 | 84 | 54 | T | |
01010101 | 85 | 55 | U | |
01010110 | 86 | 56 | V | |
01010111 | 87 | 57 | W | |
01011000 | 88 | 58 | X | |
01011001 | 89 | 59 | Y | |
01011010 | 90 | 5A | Z | |
01011011 | 91 | 5B | [ | |
01011100 | 92 | 5C | \ | |
01011101 | 93 | 5D | ] | |
01011110 | 94 | 5E | ^ | |
01011111 | 95 | 5F | _ | |
01100000 | 96 | 60 | ` | |
01100001 | 97 | 61 | a | |
01100010 | 98 | 62 | b | |
01100011 | 99 | 63 | c | |
01100100 | 100 | 64 | d | |
01100101 | 101 | 65 | e | |
01100110 | 102 | 66 | f | |
01100111 | 103 | 67 | g | |
01101000 | 104 | 68 | h | |
01101001 | 105 | 69 | i | |
01101010 | 106 | 6A | j | |
01101011 | 107 | 6B | k | |
01101100 | 108 | 6C | l | |
01101101 | 109 | 6D | m | |
01101110 | 110 | 6E | n | |
01101111 | 111 | 6F | o | |
01110000 | 112 | 70 | p | |
01110001 | 113 | 71 | q | |
01110010 | 114 | 72 | r | |
01110011 | 115 | 73 | s | |
01110100 | 116 | 74 | t | |
01110101 | 117 | 75 | u | |
01110110 | 118 | 76 | v | |
01110111 | 119 | 77 | w | |
01111000 | 120 | 78 | x | |
01111001 | 121 | 79 | y | |
01111010 | 122 | 7A | z | |
01111011 | 123 | 7B | { | |
01111100 | 124 | 7C | | | |
01111101 | 125 | 7D | } | |
01111110 | 126 | 7E | ~ | |
01111111 | 127 | 7F | DEL (delete) | 刪除 |
9 製表符 \t
10 換行符 \r
13 回車符 \n
2 瀏覽器對url的編碼
瀏覽器會對錶單中的key/val 進行編碼之後再傳遞 php腳本會自動將之解碼
編碼規則: %+字符對應的十六進制
這個是HTML實體的對照表:
php函數中 html_entity_decode 函數將HTML實體轉化成對應的char,
HTML實體表示方式 &entity_name; &#numner;(數字可以是10進制與十六進制x兩種)
php函數 html_entity_decode 的一個bug就是 不能識別 沒有分號的,但是這種沒有分號的卻可以被瀏覽器識別
字符 |
十進制字符編號 | 實體名字 | 說明 |
--- | � | --- | 未使用Unused |
--- |  | --- | 未使用Unused |
--- |  | --- | 未使用Unused |
--- |  | --- | 未使用Unused |
--- |  | --- | 未使用Unused |
--- |  | --- | 未使用Unused |
--- |  | --- | 未使用Unused |
--- |  | --- | 未使用Unused |
--- |  | --- | 未使用Unused |
--- | 	 | --- | 製表符Horizontal tab |
--- | | --- | 換行Line feed |
--- |  | --- | 未使用Unused |
--- |  | --- | 未使用Unused |
--- | | --- | 回車Carriage Return |
--- |  | --- | 未使用Unused |
--- |  | --- | 未使用Unused |
--- |  | --- | 未使用Unused |
--- |  | --- | 未使用Unused |
--- |  | --- | 未使用Unused |
--- |  | --- | 未使用Unused |
--- |  | --- | 未使用Unused |
--- |  | --- | 未使用Unused |
--- |  | --- | 未使用Unused |
--- |  | --- | 未使用Unused |
--- |  | --- | 未使用Unused |
--- |  | --- | 未使用Unused |
--- |  | --- | 未使用Unused |
--- |  | --- | 未使用Unused |
--- |  | --- | 未使用Unused |
--- |  | --- | 未使用Unused |
--- |  | --- | 未使用Unused |
--- |  | --- | 未使用Unused |
  | --- | Space | |
! | ! | --- | 驚歎號Exclamation mark |
" | " | " | 雙引號Quotation mark |
# | # | --- | 數字標誌Number sign |
$ | $ | --- | 美元標誌Dollar sign |
% | % | --- | 百分號Percent sign |
& | & | & | Ampersand |
" | ' | --- | 單引號Apostrophe |
( | ( | --- | 小括號左邊部分Left parenthesis |
) | ) | --- | 小括號右邊部分Right parenthesis |
* | * | --- | 星號Asterisk |
+ | + | --- | 加號Plus sign |
, | , | --- | 逗號Comma |
- | - | --- | 連字號Hyphen |
. | . | --- | 句號Period (fullstop) |
/ | / | --- | 斜槓Solidus (slash) |
0 | 0 | --- | 數字0 Digit 0 |
1 | 1 | --- | 數字1 Digit 1 |
2 | 2 | --- | 數字2 Digit 2 |
3 | 3 | --- | 數字3 Digit 3 |
4 | 4 | --- | 數字4 Digit 4 |
5 | 5 | --- | 數字5 Digit 5 |
6 | 6 | --- | 數字6 Digit 6 |
7 | 7 | --- | 數字7 Digit 7 |
8 | 8 | --- | 數字8 Digit 8 |
9 | 9 | --- | 數字9 Digit 9 |
: | : | --- | 冒號Colon |
; | ; | --- | 分號Semicolon |
< | < | < | 小於號Less than |
= | = | --- | 等於符號Equals sign |
> | > | > | 大於號Greater than |
? | ? | --- | 問號Question mark |
@ | @ | --- | Commercial at |
A | A | --- | 大寫A Capital A |
B | B | --- | 大寫B Capital B |
C | C | --- | 大寫C Capital C |
D | D | --- | 大寫D Capital D |
E | E | --- | 大寫E Capital E |
F | F | --- | 大寫F Capital F |
G | G | --- | 大寫G Capital G |
H | H | --- | 大寫H Capital H |
I | I | --- | 大寫J Capital I |
J | J | --- | 大寫K Capital J |
K | K | --- | 大寫L Capital K |
L | L | --- | 大寫K Capital L |
M | M | --- | 大寫M Capital M |
N | N | --- | 大寫N Capital N |
O | O | --- | 大寫O Capital O |
P | P | --- | 大寫P Capital P |
Q | Q | --- | 大寫Q Capital Q |
R | R | --- | 大寫R Capital R |
S | S | --- | 大寫S Capital S |
T | T | --- | 大寫T Capital T |
U | U | --- | 大寫U Capital U |
V | V | --- | 大寫V Capital V |
W | W | --- | 大寫W Capital W |
X | X | --- | 大寫X Capital X |
Y | Y | --- | 大寫Y Capital Y |
Z | Z | --- | 大寫Z Capital Z |
[ | [ | --- | 中括號左邊部分Left square bracket |
/ | \ | --- | 反斜槓Reverse solidus (backslash) |
] | ] | --- | 中括號右邊部分Right square bracket |
^ | ^ | --- | Caret |
_ | _ | --- | 下劃線Horizontal bar (underscore) |
` | ` | --- | 尖重音符Acute accent |
a | a | --- | 小寫a Small a |
b | b | --- | 小寫b Small b |
c | c | --- | 小寫c Small c |
d | d | --- | 小寫d Small d |
e | e | --- | 小寫e Small e |
f | f | --- | 小寫f Small f |
g | g | --- | 小寫g Small g |
h | h | --- | 小寫h Small h |
i | i | --- | 小寫i Small i |
j | j | --- | 小寫j Small j |
k | k | --- | 小寫k Small k |
l | l | --- | 小寫l Small l |
m | m | --- | 小寫m Small m |
n | n | --- | 小寫n Small n |
o | o | --- | 小寫o Small o |
p | p | --- | 小寫p Small p |
q | q | --- | 小寫q Small q |
r | r | --- | 小寫r Small r |
s | s | --- | 小寫s Small s |
t | t | --- | 小寫t Small t |
u | u | --- | 小寫u Small u |
v | v | --- | 小寫v Small v |
w | w | --- | 小寫w Small w |
x | x | --- | 小寫x Small x |
y | y | --- | 小寫y Small y |
z | z | --- | 小寫z Small z |
{ | { | --- | 大括號左邊部分Left curly brace |
| | | | --- | 豎線Vertical bar |
} | } | --- | 大括號右邊部分Right curly brace |
~ | ~ | --- | Tilde |
--- |  | --- | 未使用Unused |
  | | 空格Nonbreaking space | |
? | ¡ | ¡ | Inverted exclamation |
¢ | ¢ | ¢ | 貨幣分標誌Cent sign |
£ | £ | £ | 英鎊標誌Pound sterling |
¤ | ¤ | ¤ | 通用貨幣標誌General currency sign |
¥ | ¥ | ¥ | 日元標誌Yen sign |
| | ¦ | ¦ or &brkbar; | 斷豎線Broken vertical bar |
§ | § | § | 分節號Section sign |
¨ | ¨ | ¨ or ¨ | 變音符號Umlaut |
? | © | © | 版權標誌Copyright |
a | ª | ª | Feminine ordinal |
? | « | « | Left angle quote, guillemet left |
? | ¬ | ¬ | Not sign |
­ | ­ | Soft hyphen | |
? | ® | ® | 註冊商標標誌Registered trademark |
ˉ | ¯ | ¯ or &hibar; | 長音符號Macron accent |
° | ° | ° | 度數標誌Degree sign |
± | ± | ± | 加或減Plus or minus |
2 | ² | ² | 上標2 Superscript two |
3 | ³ | ³ | 上標3 Superscript three |
′ | ´ | ´ | 尖重音符Acute accent |
μ | µ | µ | Micro sign |
? | ¶ | ¶ | Paragraph sign |
· | · | · | Middle dot |
? | ¸ | ¸ | Cedilla |
1 | ¹ | ¹ | 上標1 Superscript one |
o | º | º | Masculine ordinal |
? | » | » | Right angle quote, guillemet right |
? | ¼ | ¼ | 四分之一Fraction one-fourth |
? | ½ | ½ | 二分之一Fraction one-half |
? | ¾ | ¾ | 四分之三Fraction three-fourths |
? | ¿ | ¿ | Inverted question mark |
à | À | À | Capital A, grave accent |
á | Á | Á | Capital A, acute accent |
? | Â | Â | Capital A, circumflex |
? | Ã | Ã | Capital A, tilde |
? | Ä | Ä | Capital A, di?esis / umlaut |
? | Å | Å | Capital A, ring |
? | Æ | Æ | Capital AE ligature |
? | Ç | Ç | Capital C, cedilla |
è | È | È | Capital E, grave accent |
é | É | É | Capital E, acute accent |
ê | Ê | Ê | Capital E, circumflex |
? | Ë | Ë | Capital E, di?esis / umlaut |
ì | Ì | Ì | Capital I, grave accent |
í | Í | Í | Capital I, acute accent |
? | Î | Î | Capital I, circumflex |
? | Ï | Ï | Capital I, di?esis / umlaut |
D | Ð | Ð | Capital Eth, Icelandic |
? | Ñ | Ñ | Capital N, tilde |
ò | Ò | Ò | Capital O, grave accent |
ó | Ó | Ó | Capital O, acute accent |
? | Ô | Ô | Capital O, circumflex |
? | Õ | Õ | Capital O, tilde |
? | Ö | Ö | Capital O, di?esis / umlaut |
× | × | × | 乘號Multiply sign |
? | Ø | Ø | Capital O, slash |
ù | Ù | Ù | Capital U, grave accent |
ú | Ú | Ú | Capital U, acute accent |
? | Û | Û | Capital U, circumflex |
ü | Ü | Ü | Capital U, di?esis / umlaut |
Y | Ý | Ý | Capital Y, acute accent |
T | Þ | Þ | Capital Thorn, Icelandic |
? | ß | ß | Small sharp s, German sz |
à | à | à | Small a, grave accent |
á | á | á | Small a, acute accent |
a | â | â | Small a, circumflex |
? | ã | ã | Small a, tilde |
? | ä | ä | Small a, di?esis / umlaut |
? | å | å | Small a, ring |
? | æ | æ | Small ae ligature |
? | ç | ç | Small c, cedilla |
è | è | è | Small e, grave accent |
é | é | é | Small e, acute accent |
ê | ê | ê | Small e, circumflex |
? | ë | ë | Small e, di?esis / umlaut |
ì | ì | ì | Small i, grave accent |
í | í | í | Small i, acute accent |
? | î | î | Small i, circumflex |
? | ï | ï | Small i, di?esis / umlaut |
e | ð | ð | Small eth, Icelandic |
? | ñ | ñ | Small n, tilde |
ò | ò | ò | Small o, grave accent |
ó | ó | ó | Small o, acute accent |
? | ô | ô | Small o, circumflex |
? | õ | õ | Small o, tilde |
? | ö | ö | Small o, di?esis / umlaut |
÷ | ÷ | ÷ | 除號Division sign |
? | ø | ø | Small o, slash |
ù | ù | ù | Small u, grave accent |
ú | ú | ú | Small u, acute accent |
? | û | û | Small u, circumflex |
ü | ü | ü | Small u, di?esis / umlaut |
y | ý | ý | Small y, acute accent |
t | þ | þ | Small thorn, Icelandic |
? | ÿ | ÿ | Small y, umlaut |