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Character Sets Used by Fonts
All fonts use a character set. A character set contains punctuation marks, numerals, uppercase and lowercase letters, and all other printable characters. Each element of a character set is identified by a number.
Most character sets used in Windows are supersets of the U.S. ASCII character set, which defines characters for the 96 numeric values from 32 through 127. There are five major groups of character sets:
· Windows · Unicode · OEM (original equipment manufacturer) · Symbol · Vendor-specific
Windows Character Set
The Windows character set is the most commonly used character set in Windows programming. It is essentially equivalent to the ANSI character set. The blank character is the first character in the Windows character set. It has a hexadecimal value of 0x20 (decimal 32). The last character in the Windows character set has a hexadecimal value of 0xFF (decimal 255). Many fonts specify a default character. Whenever a request is made for a character that is not in the font, Windows provides this default character. Many fonts using the Windows character set specify the period (.) as the default character. TrueType fonts typically use an open box as the default character.
Fonts use a break character called a quad to separate words and justify text. Most fonts using the Windows character set specify that the blank character will serve as the break character. Windows version 3.1 added 24 characters to the Windows code page, as shown in the following table.
Character Name Windows character code ‚ base line single quote 130 ƒ florin 131 „ base line double quote 132 … ellipsis 133 † dagger 134 ‡ double dagger 135 ˆ circumflex 136 ‰ permille 137 Š S Hacek 138 ‹ left single guillemet 139 Œ OE ligature 140 ' left single quote 145 ' right single quote 146 " left double quote 147 " right double quote 148 • bullet 149 - en dash 150 ¾ em dash 151 ˜ tilde 152 ™ trademark ligature 153 š s Hacek 154 › right single guillemet 155 œ oe ligature 156 Ÿ Y Dieresis 159
It should be noted that the characters for left and right single quote were first added to the character set for the release of Windows version 3.0.
Unicode™ Character Set
The Windows ANSI character uses 8 bits to represent each character; therefore, the maximum number of characters that can be expressed using 8 bits is 256 (2^8). This is usually sufficient for Western languages, including the diacritical marks used in French, German, Spanish, and other languages. However, Eastern languages employ thousands of separate characters, which cannot be encoded by using a single-byte coding scheme. With the proliferation of computer commerce, double-byte coding schemes were developed so that characters could be represented in 8-bit, 16-bit, 24-bit, or 32-bit sequences. This requires complicated passing algorithms; even so, using different code sets could yield entirely different results on two different computers.
To address the problem of multiple coding schemes, the Unicode standard for data representation was developed. A 16-bit character coding scheme, Unicode can represent 65,536 (2^16) characters, which is enough to include all languages in computer commerce today, as well as punctuation marks, mathematical symbols, and room for future expansion. Unicode establishes a unique code for every character to ensure that character translation is always accurate.
OEM Character Set
The OEM character set is typically used in full-screen MS-DOS® sessions for screen display. Characters 32 through 127 are usually the same in the OEM, U.S. ASCII, and Windows character sets. The other characters in the OEM character set (0 through 31 and 128 through 255) correspond to the characters that can be displayed in a full-screen MS-DOS session. These characters are generally different from the Windows characters.
Symbol Character Set
The Symbol character set contains special characters typically used to represent mathematical and scientific formulas.
Vendor-Specific Character Sets
Many printers and other output devices provide fonts based on character sets that differ from the Windows and OEM sets ¾ for example, the Extended Binary Coded Decimal Interchange Code (EBCDIC) character set. To use one of these character sets, the printer driver translates from the Windows character set to the vendor-specific character set.
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Íàáîðû Ñèìâîëîâ Èñïîëüçîâàííûå Øðèôòàìè
Âñå øðèôòû èñïîëüçóþò íàáîð ñèìâîëîâ. Íàáîð ñèìâîëîâ ñîäåðæèò îòìåòêè ïóíêòóàöèè, öèôð, âåðõíåãî ðåãèñòðà è ïèñüìà âåðõíåãî ðåãèñòðà, è âñå äðóãèå âûâîäèìûå ñèìâîëû. Êàæäûé ýëåìåíò íàáîðà ñèìâîëîâ íàçûâàåòñÿ ÷èñëîì.
Áîëüøèíñòâà íàáîðîâ ñèìâîëîâ èñïîëüçîâàííûõ â Îêíå - ðàñøèðåííûå íàáîðû ÑØÀ. ÍÀÁÎÐ ñèìâîëîâ ASCII, êîòîðûé îïðåäåëÿåò ñèìâîëû äëÿ 96 ÷èñëîâûõ âåëè÷èí ñ 32 ïî 127. Åñòü ïÿòü ñïåöèàëèçèðóþòñÿ ãðóïïû íàáîðîâ ñèìâîëîâ:
Îêíî Óíèêîä OEM (ÈÇÃÎÒÎÂÈÒÅËÜ) Ñèìâîë Ïîñòàâùèê-ñïåöèôè÷åñêèé
Íàáîð Ñèìâîëîâ Îêíà
Íàáîð ñèìâîëîâ Windows ÿâëÿåòñÿ íàèáîëåå îáùèì èñïîëüçîâàííûì íàáîðîì ñèìâîëîâ â Windows, ïðîãðàììèðóþùèé. Ýòî ïî ñóùåñòâó ýêâèàëåíòíîå íàáîðó ñèìâîëîâ ANSI. ×èñòûé ñèìâîë ÿâëÿåòñÿ ïåðâûì ñèìâîëîì â íàáîðå ñèìâîëîâ Windows. Ó íåãî åñòü øåñòíàäöàòåðè÷íàÿ âåëè÷èíà 0x20 (äåñÿòè÷íûå 32). Ïîñëåäíèé ñèìâîë â íàáîðå ñèìâîëîâ Windows èìååò øåñòíàäöàòåðè÷íóþ âåëè÷èíó 0xFF (äåñÿòè÷íûå 255). Ìíîãî øðèôòîâ îïðåäåëÿþò ïî óìîë÷àíèþ ñèìâîë. Âñÿêèé ðàç, êîãäà çàïðîñ ñäåëàí äëÿ ñèìâîëà, êîòîðûé - íå â øðèôòå, Windows îáåñïå÷èâàåò ýòîò ïî óìîë÷àíèþ ñèìâîë. Ìíîãî øðèôòîâ, èñïîëüçîâàâøèõ íàáîð ñèìâîëîâ Windows îïðåäåëÿþò ïåðèîä (.) êàê ïî óìîë÷àíèþ ñèìâîë. ØÐÈÔÒÛ TrueType îáû÷íî èñïîëüçóþò îòêðûòîãî áëîêà êàê ïî óìîë÷àíèþ ñèìâîë.
Øðèôòû èñïîëüçóþò ñèìâîë ïðåðûâàíèÿ íàçâàâøèé ÷åòâåðêó, ÷òîáû ðàçäåëÿòü ñëîâî è îïðàâäûâàòü òåêñò. Áîëüøèíñòâà øðèôòîâ, èñïîëüçîâàâøèõ íàáîð ñèìâîëîâ Windows îïðåäåëÿþò, ÷òî ÷èñòûé ñèìâîë ïîñëóæèò â êà÷åñòâå ñèìâîëà ïðåðûâàíèÿ. Âåðñèÿ Windows 3.1 äîáàâëÿëà 24 ñèìâîëà ê êîäîâîé ñòðàíèöå Windows, êàê ïîêàçàíî â ñëåäóþùåé òàáëèöå.
Ñèìâîëüíûé ñèìâîëüíûé êîä Èìåíè Windows åäèíñòâåííàÿ êàâû÷êà áàçîâîé ñòðîêè 130 S ôëîðèí 131 äâîéíàÿ êàâû÷êà áàçîâîé ñòðîêè 132 ýëëèïñèñ 133 êèíæàë 134 äâîéíîé êèíæàë 135 circumflex 136 permille 137 S Hacek 138 îñòàâèâøåå åäèíñòâåííûé guillemet 139 ëèãàòóðà OE 140 ' îñòàâèëà åäèíñòâåííîé êàâû÷êå 145 ' åäèíñòâåííûõ êàâû÷åê ïðàâà 146 " îñòàâèâøåå äâîéíóþ êàâû÷êó 147 " äâîéíûõ êàâû÷åê ïðàâà 148 ïóëÿ 149 - áðîñüòåñü 150 U em áðîñàòüñÿ 151 òèëüäà 152 ëèãàòóðà òîðãîâîé ìàðêè 153 Y s Hacek 154 ïðàâî åäèíñòâåííîãî guillemet 155 Z oe ëèãàòóðà 156 _ Äâå òî÷êè Y 159
Ýòî äîëæíî áûòü îòìå÷åíî, ÷òî ñèìâîëû äëÿ ëåâîé è ïðàâîé åäèíñòâåííîé êàâû÷êè ñíà÷àëà áûëè äîáàâëåíû ê íàáîðó ñèìâîëîâ äëÿ âåðñèè âåðñèè Windows 3.0.
Óíèêîä Íàáîð Ñèìâîëîâ
Ñèìâîë Windows ANSI èñïîëüçóåò 8 áèòîâ, ÷òîáû ïðåäñòàâëÿòü êàæäûé ñèìâîë; ñëåäîâàòåëüíî, ìàêñèìàëüíîå êîëè÷åñòâî ñèìâîëîâ, êîòîðûå ìîãóò áûòü âûðàæåíû èñïîëüçóÿ 8 áèòîâ - 256 (2^8). Ýòî îáû÷íî äîñòàòî÷íîå äëÿ Çàïàäíûõ ÿçûêîâ, âêëþ÷àÿ äèàêòèðè÷åñêèå çíàêè èñïîëüçîâàëñÿ â Ôðàíöóçñêîì, Íåìåöêèé, Èñïàíñêèé, è äðóãèõ ÿçûêàõ. Òåì íå ìåíåå, Âîñòî÷íûå ÿçûêè ïðèìåíÿþò òûñÿ÷è îòäåëüíûõ ñèìâîëîâ, êîòîðûå íå ìîãóò áûòü çàêîäèðîâàíû èñïîëüçîâàíèåì åäèíñòâåííîå-áàéòîâîå êîäèðîâàíèå ñõåìû. Ñ ðàñïðîñòðàíåíèåì êîìïüþòåðíîé òîðãîâëè, äâîéíîå-áàéòîâîå êîäèðîâàíèå ñõåì ðàáîòàëî ÷òîáû ñèìâîëû ìîãëè áû áûòü ïðåäñòàâëåíû íà 8- áèòå, 16-áèòå, 24- áèò, èëè 32- áèòîâûõ ïîñëåäîâàòåëüíîñòÿõ. Ýòî òðåáóåò ñëîæíîå ïðîõîæäåíèå àëãîðèòìîâ; âñå-òàêè, äðóãèå êîäîâûå êîìïëåêòû èñïîëüçîâàíèÿ ìîãëè áû äàòü ïîëíîñòüþ äðóãèå ðåçóëüòàòû â äâóõ äðóãèõ êîìïüþòåðàõ.
Äëÿ òîãî, ÷òîáû àäðåñîâàòü ïðîáëåìó êðàòíîãî, êîäèðóþùåãî ñõåìû, ñòàíäàðò Óíèêîäà äëÿ ïðåäñòàâëåíèÿ äàííûõ ðàáîòàë. 16- Áèòîâûé ñèìâîë, êîäèðóþùèé ñõåìó, Óíèêîä ìîæåò ïðåäñòàâèòü 65,536 ñèìâîëîâ (2^16), êîòîðàÿ - äîñòàòî÷íî, ÷òîáû âêëþ÷àòü âñå ÿçûêè â êîìïüþòåðíóþ òîðãîâëþ ñåãîäíÿ, à òàêæå îòìåòêè ïóíêòóàöèè, ìàòåìàòè÷åñêèõ ñèìâîëîâ, è ìåñòî äëÿ áóäóùåãî ðàñøèðåíèÿ. Óíèêîä óñòàíàâëèâàåò óíèêàëüíûé êîä äëÿ êàæäîãî ñèìâîëà, ÷òîáû ïðîâåðÿòü, ÷òî ñèìâîëüíûé ïåðåâîä âñåãäà òî÷íûé.
ÍÀÁÎÐ Ñèìâîëîâ OEM
Íàáîð ñèìâîëîâ OEM îáû÷íî èñïîëüçîâàí íà ïîëíîì-ýêðàíå ÌÑ-DOS ñåàíñû äëÿ ýêðàííîãî äèñïëåÿ. Ñèìâîëû 32 ïî 127 - îáû÷íî òå æå â OEM, ÑØÀ. ASCII, È íàáîðû ñèìâîëîâ Windows. Äðóãèå ñèìâîëû â íàáîðå ñèìâîëîâ OEM (0 ïî 31 è 128 ïî 255), ïåðåïèñûâàþòñÿ â ñèìâîëû, êîòîðûå ìîãóò áûòü îòîáðàæåíû íà ïîëíîì-ýêðàííîì ñåàíñå ÌÑ-DOS. Ýòè ñèìâîëû îòëè÷àþòñÿ îò ñèìâîëîâ Windows.
Ñèìâîëüíûé Íàáîð Ñèìâîëîâ
Íàáîð ñèìâîëîâ Ñèìâîëà ñîäåðæèò ñïåöèàëüíûå ñèìâîëû îáû÷íî èñïîëüçîâàííûå, ÷òîáû ïðåäñòàâëÿòü ìàòåìàòè÷åñêèå è íàó÷íûå ôîðìóëû.
ÍÀÁÎÐÛ Ñèìâîëîâ Vendor-Specific
Ìíîãî ïðèíòåðîâ è äðóãèõ âûõîäíûõ óñòðîéñòâ îáåñïå÷èâàþò øðèôòû îñíîâàííûå â íàáîðàõ ñèìâîëîâ, êîòîðûå îòëè÷àþòñÿ îò Windows è êîìïëåêòîâ OEM U íàïðèìåð, Ðàñøèðåííûé Äâîè÷íûé êîä Êîäèðîâàë Äåñÿòè÷íûé Êîä Âçàèìîîáìåíà íàáîðà ñèìâîëîâ (EBCDIC). ×òîáû èñïîëüçîâàòü îäèí èç ýòèõ íàáîðîâ ñèìâîëîâ, äðàéâåð ïðèíòåðà ïåðåâîäèòñÿ îò íàáîðà ñèìâîëîâ Windows äî ïîñòàâùèê-ñïåöèôè÷åñêîãî íàáîðà ñèìâîëîâ.
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